Sanqi (Radix Notoginseng) is one of the main traditional Chinese herbal medicines with great medicinal value. Drying has been shown as one of the important factors that influence the quality of Sanqi. In this study, the influence of freeze vacuum drying, hot air drying and vacuum drying on ginsenoside Rg1 content and sensory characteristics of Sanqi was compared. The ginsenoside Rg1 content of freeze vacuum-dried Sanqi was 2.37%, revealing a considerable increase when compared with vacuum-dried Sanqi and hot air-dried Sanqi. Moreover, freeze vacuum-dried Sanqi with a yellow-white, glossy, smooth and non-crack surface and a light weight, a very strong medicinal smell and a high crispness, leading to ease of breaking into pieces during packaging and distribution, scored much higher than vacuum dried Sanqi and hot air-dried Sanqi in sensory scores for overall quality characteristics. Vacuum-dried Sanqi and hot air-dried Sanqi showed a significant difference in ginsenoside Rg1 content with respective values of 1.30% and 1.11%, but no significant difference was observed in sensory scores for overall quality characteristics. Collectively, these results suggest that freeze vacuum drying allows better Sanqi quality.

Nanocrystalline cellulose was prepared from soybean dregs, rich in cellulose, using acid hydrolysis followed by high-pressure homogenization. The effects of HCl concentration, hydrolysis time, temperature and liquid-to-solid ratio on degree of hydrolysis of soybean dregs were studied using one-factor-at-a-time combined with orthogonal array design method. The optimal preparation process involved hydrolysis with 3 mol/L HCl at 100 ℃ and a liquid-to-solid ratio of 45:1 for 120 min and subsequent homogenization at 30 MPa. The results of laser particle size analysis and scanning electron microscopic (SEM) observation showed that the obtained nanocrystalline cellulose was microspheres with a particle size range of 50－100 nm. In conclusion, HCl hydrolysis followed by high-pressure homogenization allows the preparation of soybean-derived nanocrystalline cellulose

In this study, resistant starch was prepared from maize starch with pullulanase. Based on one-factor-at-a-time experiments, the main parameters of pullulanase hydrolysis were investigated by response surface methodology (RSM), including reaction temperature, pH value, reaction time, and pullulanase amount, and a mathematical model describing resistant starch yield was developed. The optimum preparation conditions were achieved as follows: pullulanase amount 12.8 ASPU/g, reaction temperature 46.2 ℃, reaction time 32 h, pH 5.0. Under these conditions, the yield of the maize resistant starch is 46.2%.

Based on one-factor-at-a-time experiments, process optimization for zein extraction using L-cysteine treatment followed by ultrasonic-assisted extraction was performed using an orthogonal array design. Zein extraction yield was investigated with respect to L-cysteine amount, ratio of liquid to material, ultrasonic treatment time, temperature and pH. The optimal process conditions for zein extraction were achieved as follows: L-cysteine amount 0.65%, ratio of liquid to material 7:1, ultrasonic treatment time 1.5 h, temperature 40 ℃, and pH 5.0. Under these conditions, the yield and purity of zein were 89.06% and 92.51%, respectively.

Using one-factor-at-a-time experiments followed by orthogonal array design, the process conditions of polysaccharide extraction from Eclipata Alba grown in Huaguo Mountain were optimized in this study. Also, a comparison of antioxidant activity was carried out between polysaccharides (PEA) and flavonoids (FEA) from Eclipata Alba. The results showed that the optimum conditions for polysaccharide extraction were material-to-liquid ratio of 1:15 (g/mL), extraction time of 1 h, extraction temperature of 90 ℃ and extraction number of 3. After the removal of impurities such as proteins, nucleic acids, etc, the extracted polysaccharides were characterized using ultraviolet spectroscopy and infrared spectroscopy. Both PEA and FEA had a powerful ability to scavenge hydroxyl and superoxide anion radicals and could scavenge the former more powerfully. At the same concentrations exceeding 0.085 mg/mL, FEA indicated stronger antioxidant activity than PEA.

The optimal conditions for the hydrolysis of Lisbon yam flour by thermostable α-amylase were investigated by one-factor-at-a-time and orthogonal array design methods in order to maximize total reducing sugar content in hydrolysates. Meanwhile, the hydrolysis process was analyzed kinetically. The best results of the hydrolysis were achieved after 50 min incubation of 40 mg/mL Lisbon yam flour and 0.07 mL/g thermostable α-amylase at 90 ℃ and pH 5.6, and the resulting total reducing sugar content in hydrolysates, Vm and Km were 52.95%, 1.26 mg/(mL ·min) and 80.84 mg/mL, respectively.

The optimum conditions for the extraction of flavonoids from Robinia pseudoacacia L. flowers were determined using response surface methodology. On the basis of one-factor-at-a-time experiments, Box-Benhnken central composite design was applied to investigate the effects of three variables, namely alcohol concentration, liquid-to-solid ratio and microwave heating time on extraction yield of flavonoids. A regression model describing extraction yield of flavonoids as a function of these three variables was established. The best results of the extraction of flavonoids from Robinia pseudoacacia L. flowers were obtained when the samples were extracted twice by means of microwave heating for 145 s at a ratio of liquid to solid of 37:1 using 75% ethanol. Under these conditions, the extraction yield of flavonoids was 8.63 mg/g.

Based on one-factor-at-a-time experiments, response surface methodology was used to optimize the extraction of red pigments from the fresh fruits of Acanthopanax senticosus Harms wildly grown in Changbai Mountain. The optimal extraction conditions were found as follows: 36.83% ethanol as extraction solvent, 23.78:1 material-to-liquid ratio, and 2.05 h extraction time. Under these conditions, the predicted and experimental absorbance values at 525 nm of extracts was 0.756 and 0.751, respectively.

In order to maximize extraction efficiency of flavonoids from Euryale ferox leaves, Plackett-Burman design was used to screen 4 main variables (ratio of material to liquid, ultrasonic power, ethanol concentration and extraction time) that influence extraction efficiency out of 5 process parameters (ratio of material to liquid, ultrasonic power, ethanol concentration, temperature and extraction time) and the selected variables were then optimized using orthogonal array design. The optimum conditions for flavonoid extraction from Euryale ferox leaves were determined as follows: 1:25 ratio of material to liquid (g/mL), 175 W ultrasonic power, 85% ethanol as extraction solvent, and 40 min extraction time. Under such conditions, the extraction efficiency of flavonoids was 90.28 mg/g.

In order to optimize the extraction of antioxidant components from cherry seed, an investigation into the effects of three operating parameters including ethanol concentration, temperature and extraction time on DPPH free radical scavenging activity of extracts was studied by means of response surface methodology (RSM). It was found that the optimal process conditions were liquid/material ratio 20:1 (mL/g), ethanol concentration 33% (V/V), extraction temperature 60 ℃, and extraction time 31 min. Under these extraction conditions, the DPPH free radical scavenging activity of the obtained extract from cherry seed was up to 92.58%, which was very close to the predicted value. Accordingly, the optimal process established in this study has good feasibility.

Purpose: A solid-phase extraction procedure for the separation and purification of naringin (NG) was developed using strong anion exchange (SAX) cartridge. Method: Naringin was adsorbed onto the cartridge by electrostatic interaction between naringin and functional groups. Several variables affecting the elution performance of SAX, such as ionic strength of elution, elution volume and elution rate, were studied. Results: The application of 5 mL of sodium bicarbonate solution (0.1 mol/L, pH = 9.0) to elute SAX cartridge at a flow rate of 0.5 mL/min resulted in a recovery rate of 91%. Conclusions: The established method is simple and efficient.

The main goals of the current study were to optimize the ultrasonic-assisted extraction process for anthocyanins from purple potato, purify extracts using NKA-9 macroporous adsorption resin, and separate and identify anthocyanin constituents. The optimal conditions for anthocyanin extraction were found as follows: 2.5% citric acid aqueous solution as extraction solvent at a material-to-liquid ratio of 1:50 and 400 W ultrasonic power for an extraction duration of 10 min at 45 ℃. Under these conditions, the extraction yield of anthocyanins from purple potato was 1.362 mg/g (dry weight). Further, anthocyanins with 98.35% recovery and 90.23% purity were obtained after purification using NKA-9 macroporous adsorption resin as a result of elution with 8 bed volumes of pH 2.5, 55% ethanol aqueous solution containing citric acid. Using HPLC, 5 anthocyanin fractions were identified, including cy-3-glu, cy-3-rut and pn-3-glu with respective contents of 0.27, 0.057 and 0.46 mg/g sweet potato (dry weight), altogether accounting for 57.78% of total anthocyanins. The retention time of the most predominant anthocyanin was 12.224 min, while the structure was unknown.

Here, we compared the effectiveness of three treatment methods (35% ethanol coating, steaming and freezing) for the deastringency of Russian olive fruits. For the determination of tannin content, control and treated fruits were separated into peel, flesh and core and whole fruits and the tissue fractions were pulverized and sieved. Tissue fractions varied in tannin content. Flesh powder showed the highest tannin content, reaching 8.670 g/kg, followed by whole fruit powder, peel powder and core powder with respective tannin contents of 8.145, 6.832 g/kg and 3.940 g/kg. Furthermore, better deastringency of Russian olive fruits was achieved using 35% ethanol coating compared with steaming and freezing.

In the extraction of nomilin from orange peel with supercritical CO2, four operating parameters including time, temperature, pressure and entrainer (anhydrous ethanol) amount that affect extraction yield of nomilin were investigated using response surface methodology (RSM). A mathematical model describing the relationship between them was set up. The operating parameters could be ranked in decreasing order of influence as follows: time, pressure, temperature and entrainer amount. Response surface analysis of the developed model showed that the optimal extraction conditions were 2 h, 50 ℃, 30 MPa and 1.51 mL/g entrainer amount. Under the conditions, the predicted and experimental extraction yields of nomilin were 54.26 mg/kg and 53.87 mg/kg, respectively, showing no significant difference. Moreover, the experimental data were well fitted with the developed model.

In order to optimize the manufacturing of sulfur-free and low-sugar preserved lotus root, one-factor-at-a-time method combined with an L9(34) orthogonal array design was employed to study the effects of browning inhibitors and sugar permeation by means of microwave radiation on browning degree and sugar content in preserved lotus root, respectively. The best results of color protection of lotus root chips were achieved using a compound browning inhibitor composed of 0.40% L-cystine, 0.15% EDTA-Na2 and 0.20% salt. Sugar permeation for 20 min in 30% sugar solution under the radiation of 40% fire (320 W) microwave proved optimal.

Amano protease P was selected as the most suitable enzyme out of 5 proteases for preparing royal jelly-derived peptides with high angiotensinⅠconverting enzyme (ACE) inhibitory activity. Using one-factor-at-a-time method in combination with quadratic rotary orthogonal combination design, the optimal conditions for the hydrolysis of royal jelly by the selected enzyme for further improving ACE inhibitory rate of hydrolysates were 196 min, 0.0653 g/mL substrate concentration and 1503 U/g enzyme amount, resulting in an experimental ACE inhibitory rate of 79.75%, representing 98.08% of the theoretical value. Hydrolysis time and substrate concentration had extremely significant effect on ACE inhibitory rate of hydrolysates (P＜0.01) and enzyme amount had significant effect (P＜0.05). In conclusion, royal jelly almost has no ACE inhibitory activity, while royal jelly-derived peptides resulting from Amano protease P-catalyzed hydrolysis have powerful ACE inhibitory activity.

The protective effects of 6 color protection agents against the browning of walnut kernel pellicle were compared, and the individual and combined effects of the selected color protection agents citric acid, EDTA-2Na and CaCl2 on inhibiting the browning of walnut kernel pellicle were further studied using one-factor-at-a-time method combined with an L9(34) orthogonal array design to find out the best combination of color protection agents. The results showed that 1.0 g/L citric acid + 6.5 g/L EDTA-2Na + 25.0 g/L CaCl2 had the best protective effect on the color of walnut kernel pellicle. Citric acid improved the color of walnut kernel pellicle most significantly, followed sequentially by EDTA-2Na and CaCl2. The results of SPSS analysis indicated that citric acid and EDTA-2Na had a significant effect on color protection of walnut kernel pellicle while the effect of CaCl2 was not statistically significant.

The present study was conducted to test the individual and combined effects of 4 natural hydrophilic colloids such as sodium alginate, guar gum, xanthan gum and pectin on the suspension stability of yam juice, evaluated in terms of turbidity difference before and after sample centrifugation. The results indicated that the individual effects of sodium alginate, guar gum and pectin on the suspension stability of yam juice were statistically significant and regulative. The best suspension stability of yam juice was achieved by using all of them: 0.17% sodium alginate, 0.10% guar gum and 0.17% pectin.

Macroporous resin adsorption was used to purify flavonoids and triterpenoids from crude extract resulting from sequential organic solvent extraction of the whole plant of Kalimeris indica (L.) Sch-Bip. with 80% ethanol, petroleum ether (decolorization) and ethyl acetate and their lipid peroxidation inhibitory activity in vitro was measured. AB-8 was selected as the best resin out of 15 ones by comparing their static adsorption and desorption, adsorption kinetic characteristics and isothermal adsorption curves. Kinetic adsorption and desorption on AB-8 column were used to purify flavonoids and triterpenoids. The results of elution with different concentrations of ethanol showed that 20% ethanol eluate contained the largest amount of flavonoids, reaching 62.7%, and 19% triterpenoids with a total yield of 51.5% and that 60% ethanol eluate had the highest triterpenoid content, reaching 58.5% with a total yield of 22.3%. Both constituents had some inhibitory effect on lipid peroxidation in mouse heart, liver, kidney and brain tissues in vitro, especially on the liver.

One-factor-at-a-time method combined with orthogonal array design was employed to optimize enzymatic extraction of polysaccharides from squid ink with alkaline protease. The antioxidant activity of polysaccharides from squid ink was investigated by DPPH and hydroxyl free radical scavenging assays and ferric reducing assay. The optimal conditions for polysaccharide extraction were 4.5% enzyme amount, 1:15 material-to-liquid ratio, 50 ℃, pH 8 and 4 h, resulting in a polysaccharide yield of 3.63%. Squid ink polysaccharides had some antioxidant activity. A positive liner correlation between the antioxidant activity and concentration of squid ink polysaccharides was found over the investigated ranges. The The half maximal inhibitory concentrations (IC50) against DPPH and hydroxyl free radicals were 3.61 mg/mL and 8.06 mg/mL respectively.

Ultrasound at 100 kHz was used to enhance the extraction of polyphenolic compounds from Satsuma mandarin peel by the conventional soaking method. It was found that the addition of ultrasound assistance during the soaking of Satsuma mandarin peel in 80% methanol aqueous solution allowed more effective and efficient extraction of phenolic acids at low temperature. The effects of ultrasound treatment time, extraction temperature and ultrasound power on phenolic acid content and antioxidant capacity of extracts were studied and the results indicated that extraction temperature had the most important effect. A considerable increase of phenolic acid content in Satsuma mandarin peel extracts was observed with increasing temperature, while prolonged ultrasound treatment time resulted in a significant reduction of phenolic acid content at 40 ℃. Moreover, an excellent linear relationship between total phenolic content and antioxidant capacity of Satsuma mandarin peel extracts was found, revealing a R2 of 0.8435, 0.8895, 0.8622 at 15, 30 ℃ and 40 ℃ and of 0.7971 at various ultrasound power levels, respectively. Accordingly, Satsuma mandarin peel is an abundant source of antixodiants. This study also demonstrates that ultrasound assistance can effectively increase phenolic acid content and antioxidant capacity of Satsuma mandarin peel extracts.

Crude phytase solution separated from Agrobacterium radiobacter fermentation broth was used to hydrolyze wheat bran for phytic acid dephosphorization. Using one-factor-at-a-time combined with orthogonal array design method, such process conditions as enzyme amount, substrate concentration, pH, temperature and hydrolysis time were optimized to be 750 U/g, 40 mg/mL, 7, 45 ℃, and 5 h, respectively. Under the optimized conditions, the hydrolysis rate of phytic acid was up to 81.50%.

The ultrasonic-assisted extraction of pigments from Acanthopanax senticosus Harms fresh fruit was optimized by employing a four-factor three-level Box-Behnken experimental design and response surface analysis. Results showed that the optimal extraction conditions were 37.5% ethanol as extraction solvent at a liquid/material ratio of 9:1 (mL/g), 170 W ultrasonic power and 43 min ultrasonic treatment time. The extract solution obtained under the optimal conditions revealed an absorbance of 0.791 at 525 nm.

In order to make full use of golden cuttlefish eyes, the enzymatic preparation of hyaluronic acid (HA) from the waste of golden cuttlefish processing was studied. The results of a comparison of 3 proteases showed that neutral protease was more suitable to hydrolyze golden cuttlefish eyes than pepsin and trypsin, providing an HA extraction yield of 6.64%. Employing one-factor-at-a-time experiments and response surface methodology, the optimal conditions for HA extraction by neutral protease-catalyzed hydrolysis were determined as follows: 8200 U/g enzyme amount and 60 ℃ for a reaction duration of 3 h. Under these conditions, the experimental extraction yield of HA was up to 10.70%, in close agreement with the predicted value. Accordingly, the established extraction process was accurate and feasible. It was also found that enzyme amount was the most important fact the affects extraction yield of HA followed by temperature and reaction time.

Under the combined assistance of microwave and ultrasonic, the synthesis of 2-methylbenzoxazole for use as a food flavor via the polyphosphoric acid-catalyzed reaction between 2-aminophenol and acetic acid was studied. Experimental investigations into the effects of catalyst type, 2-aminophenol-to-acetic acid molar ratio, 2-aminophenol-to-polyphosphoric acid (PPA) mass ratio, microwave power, ultrasonic power, microwave treatment alone, reaction temperature and reaction time on reaction yield of 2-methylbenzoxazole were carried out. The results showed that the optimal synthesis conditions of 2-methylbenzoxazole were microwave power of 800 W, ultrasonic power of 800 W, 2-aminophenol-to-PPA ratio of 3:4, acetic acid-to-2-aminophenol ratio of 7.6:1, reaction time of 25 min, and reaction temperature of 115 ℃. This optimized reaction and subsequent vacuum distillation resulted in a 2-methylbenzoxazole yield of 78.20%. The structure of the synthesized 2-methylbenzoxazole was confirmed by IR, MS and 1H NMR. The established process for 2-methylbenzoxazole synthesis from the inexpensive and easily available materials had the advantages of short reaction time, high yield and easy operation resulting from the synergistic action of microwave and ultrasonic and allowed the formation of purely aromatic products.

Ultrasound-assisted extraction and subsequent MgO column chromatography was used to purifyβ-carotene from elenium-enriched wheat seedling. The quantitative analysis ofβ-carotene was performed using high performance liquid chromatography (HPLC). Using orthogonal array design method, the optimal process parameters for ultrasound-assisted extraction of carotenoids from wheat seedling were petroleum ether-acetone mixture with a ratio of 95:5 (V/V) as the extraction solvent at a material/liquid ratio of 1:50 for triple repeated extraction at room temperature under the assistance of 300 W ultrasound power for 50 min each time. Under the optimal extraction conditions, the yield of carotenoids andβ-carotene from wheat seedling were up to 12.85 mg/g and 4.86 mg/g, respectively. Multiple adsorption peaks of the obtained extract were observed at 447 nm, which suggested that the composition of pigments in wheat seedling was complicated. The recovery ofβ-carotene was 93.37% after purification by MgO column chromatography. The purifiedβ-carotene presented an absorption peak at the retention times of 17.138 min and 16.726 min, respectively, suggesting the possible presence of some compounds with similar chemical structures.

Objective: To optimize the extraction of soluble dietary fiber (SDF) from grape pomace with hydrochloric acid. Methods: One-factor-at-a-time experiments, mathematical modeling based on Box-Behnken experimental design and multiple regression analysis and response surface analysis were carried out to investigate the individual and interactive effects of various process conditions on extraction yield of SDF and their significance. Response surface and contour plots were drawn with extraction yield of SDF as a function. Results: The optimal conditions for SDF extraction were 0.40 mol/L hydrochloric acid as extraction solvent at a material-to-liquid ratio of 1:12 (g/mL) and 75 ℃ for an extraction duration of 90 min. Under the optimal extraction conditions, the yield of SDF was up to 47.56 mg/g, which was close to the model-predicted value. Conclusion: The developed regression equation can be well fitted with experimental results and is reasonable, reliable and applicable for actual prediction.

In this work, we optimized the preparation of purple potato granule for minimizing free starch content and maximizing pigment retention. It was found that the appropriate preparation process involved two-step cooking and subsequent backfill pulverizing. The optimal two-step cooking conditions were precooking in 30 × 10-6 g/mL CaCl2 solution at 70 ℃ for 28 min and then cooking for 32 min. The optimal backfill pulverizing conditions were backfill in a proportion of 1:2 followed by emulsifier addition at 0.3% and stirring for 2.5 min. Purple potato granules of 80, 100 and 120 mesh in granularity were prepared under the optimized conditions, and a comparative analysis was carried out on their color difference (δE) values and iodine values. The purple potato granule of 80 mesh showed the lowest free starch content and the best color retention.

In order to provide an experimental basis for enriching linoleic acid from corn embryo oil, the saponification of corn embryo oil with 95% ethanol and KOH and the methyl esterification of the resulting fatty acids with concentrated H2SO4-methanol were studied. After 100 min of refluxing on 80 ℃ water bath, corn embryo oil was most completely hydrolysis and the acid value was up to 207.85 mg KOH/g when 95% ethanol and KOH were added at 2 mL/g and 1.1-fold saponification equivalent. The most complete methyl esterification of the resulting fatty acids was achieved after 30 min of catalysis by concentrated H2SO4-methanol at 5:95 (V/V) added at 5 mL/g on 70 ℃ water bath, resulting in 100% esterification confirmed by GC. Linoleic acid with 96.98% purity was obtained after urea inclusion fractionation of fatty acids resulting from the saponification of corn embryo oil under optimized conditions.

Porkchop soup was prepared by a high-pressure four-stage process and then stored at 4 ℃. During storage period, nutritional components, TVB-N, bacterial count and protein digestibility of the porkchop soup were studied. A dynamic model was established to predict and control the storage quality and shelf life of the porkchop soup during storage. The results showed that bacterial count in muscle and soup exhibited an increase trend, and protein degradation and nutritional quality deteriorations were observed during the storage period. Meanwhile, a series of biochemical changes in the porkchop soup were observed, which could be well fitted with the first-order chemical reaction dynamic model.

Chrysanthemum has great medicinal value and its infusion can also be drunk and is very popular in China. Chlorogenic acid and total flavonoids are important components in Chrysanthemum. The contents of total flavonoids and chlorogenic acid in Chrysanthemum were measured by HPLC in this study. We found that after infusing 2 g of Chrysanthemum in 120 mL of 100 ℃ water for 15 min once, both the contents of total flavonoids and chlorogenic acid in the obtained infusion reached maximum.

The separation performance of columns with different polarities, including HP-5, DB-Wax and SPB-50 column, for 37 fatty acid methy esters (FAMEs) was comparedgas chromatography-mass spectrometry (GC-MS). The results showed that these columns allowed FAMEs separation. The peaks of FAMEs with less carbon atoms were separated earlier. FAMEs with the same number of carbon atoms and different degree of saturation were separated in different orders on the stationary phases. SPB-50 column could separate cis/trans, ω-3 and ω-6 fatty acids more sufficiently and may be a more suicolumn for complicated FAME sample analysis, especially for functional fatty acids.

To investigate the influence of data processing on the expanded uncertainty accuracy in the chemical determination of nitrite in pickles, the uncertainty components of calibration curve were fitted with a general linear model and a more rigorous nonlinear model, respectively. Meanwhile, the uncertainty components of solution volume were assessed with a general body expansion coefficient method and a more strict density correction method, respectively. The uncertainty components of spike recovery were evaluated using an approximate formula and a more rigorous formula. The results showed that the expanded uncertainty accuracy obtained from the strict method was higher than that from the general method. For those test results close to the limited boundary, the strict methods, but not the general methods could be used to evaluate the quality of nitrite determination. When the correct testing process is followed, a higher and reasonable evaluation accuracy can be achieved using real data.

Near-infrared spectroscopy combined with chemometric methods was employed to determine the acid value of third grade soybean oil as an improvement over the current methods. The characteristic waveband of 4500－6000 cm-1 was selected to establish an acid value calibration model. Spectral pre-processing methods based on wavelet transform were investigated and the effects of different wavelet decomposition levels on prediction results of acid value were compared in detail. The results showed that Daubechies4 (db4) wavelets with four levels of decomposition revealed the best noise removal. A back propagation (BP) neural network calibration model was built based on reconstructed spectral signals with wave filtrating and was validated using the prediction set with a determination coefficient of 0.9743 and a RMSEP of 0.1036. This study supports a high feasibility to apply near-infrared spectroscopy for the rapid determination of acid value of oils.

Forty Chinese wolfberry samples from 8 different regions of China were scanned with a near infrared (NIR) spectrophotometer. The original spectra were preprocessed by the first derivative (5 point smoothing) and standard normal variate (SNV) and were subjected to principle component analysis over the wavelength range of 950 nm to 1650 nm, in which the number of principal components was selected as 3. A robust model indicating each geographic origin of Chinese wolfberry was achieved using the SIMCA (Simple Modelling of Class Analogy) pattern recognition method and its reliability at the 5% significance level was validated. The results revealed that the model indicating samples from Qinghai exhibited a recognition rate of 80% in the calibration set, the recognition rates for other 7 cultivation regions were all 100%, and the rejection rates were 100%, 100%, 97%, 100%, 91%, 94%, 97% and 100%, respectively. All the recognition rates of the 8 cultivation regions were 100% in the validation set, and the rejection rates were 100%, 100%, 100%, 100%, 75%, 88%, 100% and 100%, respectively. These results support the feasibility of applying NIR to identify the geographic origin of Chinese berry.

A method was developed for the determination of volatiles in Chinese rice wine with different aging times by gas chromatography-mass spectrometry (GC-MS) with sorptive extraction. Solid phase microextraction (SPME) and stir bar sorptive extraction (SBSE) were compared to select the best extraction method among the two. Compared with SPME, SBSE resulted in a higher-fold enrichment and a lower limit of detection. The average relative standard deviation (RSD) of the developed SBSE/GC-MS method (6 parallel determinations) was 11.47% and the recoveries for isobutyl alcohol, furfural and ethyl acetate were in the range of 88.6%－92.3%, suggesting its good stability. Sixty volatiles were identified and quantified, including 15 alcohols, 25 esters, 6 aldehydes and 5 acids, and others. With increasing aging time, ethanol concentration showed a gradual decrease, while the concentrations of 11 esters, 1 alcohol, 1 ketone and 1 aldehyde gradually increased. These changes may be caused by the oxidation of alcohols and aldehydes into acids followed by the esterification of acids and alcohols during storage. In conclusion, SBSE/GC-MS is a reliable method allowing the determination of volatiles in Chinese rice wine.

In this paper, an intellectual electronic nose system that can rapidly distinguish beer brands is described. The system mainly consisted of data acquisition, modification and transmission unit, sensor array and gas chamber, and power and gas supply unit. Five different brands of beer were distinguished by the system in combination with the stochastic resonance data processing method with considerable avoidance of the negative effect of sensor baseline drift. Our results demonstrate that the system allows rapid and effective distinguishing of beer brands with good reproducibility and will therefore have a promising prospect for practical applications.

An analytical method was established for determining geosmin (GEO) and 2-methylisoborneol (MIB) as off-odor compounds in freshwater fish using gas chromatography-mass spectrum (GC-MS) based on microwave assisted distillation followed by solid phase microextraction. Such sample preparation parameters as microwave power, distillation time and carrier gas flow rate were optimized to be 360 W (40% of the maximum power), 6 min, and 60 mL/min, respectively. Under the optimized conditions, the detection limits were 0.044 μg/kg for GEO and 0.095 μg/kg for MIB. A good linearity was observed for GEO and MIB over the concentration range of 0.5 to 20 μg/kg with r2 of 0.998 and 0.991, respectively. The recoveries were 42.7% for GEO and 61.9% for MIB. Using this method, the contents of GEO and MIB in a commercially available tilapia meat sample were determined to be 4.97 μg/kg and 1.21 μg/kg, respectively.

The specific fragments of potato pyrophosphorylase gene (UGPase, U20345) and tomato polygalacturonase-2a gene (PG-2a, X04583.1) were identified by BLAST analysis and multiple sequence alignment. Two pairs of primer were subsequently designed and demonstrated high specificity by PCR. A new method was developed to detect potato and tomato product simultaneously by duplex PCR, and 1.25 ng of mixed potato and tomato DNA was successfully detected. With high specificity and sensitivity, this method is applicable for the detection of potato and tomato products by entry-exit inspection and quarantine departments.

Response surface methodology was employed to optimize three operating conditions for cadmium determination in table vinegar by graphite furnace atomic absorption spectrometry (GFAAS). On the basis of one-factor-at-a-time experiments, absorbance at 228.8 nm of tested samples was modeled against NH4H2PO4 concentration, ashing temperature and atomization temperature using a three-variable three-level Box-Benhnken experimental design combined with multiple regression analysis. The built regression model was analyzed by response surface methodology. It was found that the optimal determination conditions were 4.24 mg/mL NH4H2PO4 concentration, ashing 1013 ℃, and atomization at 1921℃. Under these conditions, the predicted values showed a good agreement with the experimental values. Using the optimized GFAAS method, the content of cadmium in a commercial vinegar sample was determined to be 0.188 μg/mL with a spike recovery of 98.76% and a relative standard deviation of 2.68%.

A spectrophotometric method to determine the degree of substitution (DS) of hydroxypropyl starch is reported in this paper. Factors that affect the determination were investigated. The optimal sample preparation conditions were heating for 3 min in boiling water bath followed by ninhydrin addition after cooling down to 5 ℃ in ice bath and then reheating in 25 ℃ water bath for 60-100 min. The detection wavelength was selected as 590 nm. Under these conditions, the built standard curve displayed a good linearity. This method allowed the determination of degree of substitution of hydroxypropyl starch with a high repeatability.

A new fixed pH method for the continuous determination of total acidity and crude protein in Rumex dentatus whole plant was established. The acids in samples were extracted by formaldehyde with the aid of ultrasound, and a fixed pH titration method was used to determine the total acidity using KOH as a standard solution. After the determination of the total acidity, the excessive formaldehyde in the sample solution was removed and then digested with concentrated sulfuric acid. The extra sulfuric acid was neutralized and the NH4＋dissociated into H+ by formaldehyde. The crude protein was determined by fixed pH titration method using KOH as the standard solution as well. The total acidity (H＋) of a dried sample was 0.9178 mol/kg with a relative standard deviation less than 5% (n= 6), and the crude protein was 15.30 g/100 g with the relatively standard deviation less than 3% (n = 6). These results indicated no obvious difference from those determined by the national standard method. In conclusion, the method has been proven to has many advantages such as simplicity, rapidity, easy operation, low regent consumption, short assay time, thus deserving to be popularized.

A gel permeation chromatography-phase high performance liquid chromatography (GPC-HPLC) was developed to determine benzo(a)pyrene residues in edible vegetable oils. In this method, sample pretreatment was achieved using gel permeation chromatography (GPC), and benzo(a)pyrene residues in samples were determined by reversed-phase high performance liquid chromatography (RP-HPLC) with fluorescence detection using retention time for qualitative analysis and external standards for quantitative analysis. The results showed that over the range from 0 to 20 μg/L, the correlation coefficient of benzo(a)pyrene was 0.9998. The detection limit of benzo(a)pyrene in edible vegetable oil was 0.1 μg/kg. The mean spike recoveries of benzo(a)pyrene were from 88.3% to 94.4% across three spike levels with a relative standard deviation (RSDs) ranging from 2.3% to 4.9%. The sensitive and accurate method allowed the determination of benzo(a)pyrene in 5 different quality control samples with satisfying results, suggesting its good applicability in practice.

In this paper, we report a method that allows the simultaneous determination of 6 preservatives including benzoic acid, sorbic acid, dehydroacetic acid and 3 p-hydroxybenzoates in soya sauce. The preservatives in samples were extracted with 20% methanol, separated on a C18 column using a mobile phase made up of methanol and 1.55 g/L ammonium acetate, and detected with a diode array detector. All six preservative compounds were separated successfully and showed a good linear relationship between their concentrations and peak areas. The mean recovery rates across three spike levels were 89%-103% with a RSD ranging from 1.09% to 2.81%. Our results demonstrate that this method is sensitive, selective, simple, convenient and high-recovery and allows the routine determination and food safety control of soya sauce.

To investigate the effect of sampling position on intramuscular lipid content and fatty acid composition of pork, the muscles from four carcass positions of Rongchang pig breed were measured for their lipid content, fatty acid composition of total intramuscular lipids, phospholipids and triglycerides and free fatty acid composition. The results showed that significant differences in intramuscular total lipid content and triglyceride content were observed among four positions (P ＜0.05), while phospholipids and free fatty acids showed no significant difference (P ＞ 0.05). In addition, the differences in the fatty acid composition of intramuscular total lipids and free fatty acids among four positions were significant (P＜ 0.05), while no significant differences in phospholipids or triglycerides were observed (P ＞ 0.05). The effect of free fatty acids on fatty acid composition of intramuscular total lipids was very limited due to its low percentage in intramuscular lipids, so the significant differences in intramuscular total lipid content and fatty acid composition among four positions of Rongchang pig was mainly caused by the difference of intramuscular triglyceride content.

The volatile composition of a foreign dairy flavoring was analyzed by GC/MS after solid-phase microextraction using 3 different types of extraction fibers. A total of 39, 41 and 40 volatile compounds were identified with CAR/PDMS fiber, PDMS/DVB fiber, and CAR/PDMS/DVB fiber, respectively. The results of the three different kinds of fibers complemented each other, and a total of 51 volatile compounds were identified in this dairy flavor, among which, esters, aldehydes, ketones and lectones were the dominant components and their concentrations (26.12%, 25.95%, and 15.16 %) were higher than those of others.

The mannitol content of the mycelium of Paecilomyces tenuipes and its culture medium was analyzed colorimetrically at 412 nm. The effects of extraction solvent, temperature and time on extraction yield of mannitol were investigated to optimize the extraction conditions. The best results of mannitol extraction were achieved by using distilled water to extract Paecilomyces tenuipes mycelium at 60 ℃ and extract its culture medium at 100 ℃ for 60 min both. Under these conditions, the recovery rate of mannitol from Paecilomyces tenuipes mycelium was 99.94% with a RSD of 0.74%, the precision RSD was 0.80% and a good stability of the OD value at 412 nm was found within 60 min. In the case of mannitol extraction from the culture medium, the recovery, RSD and precision RSD were 99.79%, 1.17%, and 1.00%, respectively, and the OD value at 412 nm also showed a good stability within 60 min.

Purpose: To comparatively analyze the composition of volatile compounds in fresh and thermoprocessed bigeye tuna meat. Methods: Headspace solid-phase microextraction method (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) was used for the analysis of volatiles. Results: Totally 36 and 47 volatile compounds were detected from fresh and thermoprocessed bigeye tuna, respectively. Among them, the predominant compounds were aldehydes, ketones, alcohols, and furans, which were together responsible for the specific flavor of bigeye tuna. Aldehydes and alcohols played a major role in fresh bigeye tuna, especially 2,4-pentadiene aldehyde (31.74%) and 1-octene-3-ol (7.8%). However, in thermoprocessed bigeye tuna, aldehydes and furans compounds had the greatest contribution to the flavor with their relative contents of 64.09% and 11.41% respectively. Conclusions: Aldehydes, alcohols, ketones, and furans have an important influence on the flavor of bigeye tuna meat. The flavor of thermoprocessed bigeye tuna meat may come from proteolysis, lipolysis and Maillard reaction.

Trace chromium (VI) catalyzes the oxidation of crystallized violet and methyl green by potassium chlorate in dilute H2SO4 solution, which will cause the discoloring of the solution. A dual-wavelength and dual-indicator catalytic kinetic spectrophotometric method to quantify the concentration of chromium (Ⅵ) was proposed by determining the difference of absorbance (δA) of the reaction solution with and without trace chromium (Ⅵ) as catalyst. The results showed that limit of detection of the proposed method was 0.003 mg/L and that the recovery for chromium (Ⅵ) was between 98.3% and 102.0% with a relative standard deviation of less than 2.7%. The linear range was 0.045－0.200 μg/mL. Our results demonstrate that this method is simple, convenient and applicable in practice.

The volatile compounds in Hutongfang Beijing-style sauce chicken were extracted by simultaneous distillation extraction (SDE) method and determined using gas chromatography-mass spectrometry (GC-MS). Totally 84 volatile flavor compounds were identified, including 9 groups: 4 hydrocarbons, 19 aldehydes, 10 ketones, 1 ethers, 12 alcohols, 11 acids, 4 ester, 5 phenols and 16 nitrogen- or sulfur-containing or heterocyclic compounds, accounting for 0.325 %, 52.262 %, 0.929 %, 0.150 %, 1.995 %, 39.117 %, 0.408 %, 0.345 %, and 4.468 % of the total amount of volatile compounds, respectively. Meanwhile, we also found that aldehydes, nitrogen- or sulfur-containing compounds and heterocyclic compounds were the main flavor compounds of Hutongfang Beijing-style sauce chicken.

A method for the determination of methyltestosterone in tilapia muscle using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed. Deuterium-labeled methyltestosterone was used as internal standard and added to the sample before being extracted with acetonitrile. The extract was partitioned into ethyl acetate and cleaned up on a strong anion exchange column. Subsequently, the eluates were further extracted with n-hexane and cleaned up on a magnesium silicate solid phase extraction cartridge before UPLC-MS/MS determination. The mass spectrometer was operated in the positive ion mode using selected ion monitoring for qualitative and quantitative analysis of methyltestosterone. The limit of detection was 0.4 μg/kg and the limit of quantitation was 1μg/kg. The calibration curve was linear with a correlation coefficient of over 0.999 within the concentration range of 1－60μg/kg. The average recoveries for methyltestosterone were 71.06%－83.06% across three spike levels (n＝5) with a relative standard deviation (CV) between 7.4% and 15.3%. These results demonstrate that this method fully meets the requirements for the determination of methyltestosterone residue in imported and exported tilapia muscles for the purpose of ensuring food safety.

A high performance liquid chromatography with refractive index detection (HPLC-RI) method was established for the simultaneous quantification of glucose, sucrose and maltose. The chromatographic separation was achieved on a Sugar-D column using a mixture of acetonitrile and water (V/V＝78:22) as mobile phase at a flow rate of 1.0 mL/min. Under these conditions, glucose, sucrose and maltose could be well separated. A good linear relationship for each analyte was observed over the concentration range of 0.50－10.00 mg/mL. The spike recoveries of glucose and sucrose were 94.3%－103.7% and 101.4%－105.1% respectively. The results of uncertainty evaluation indicated that the combined standard uncertainty was 1.92% and the expanded uncertainty was 4.1%. The method was simple, accurate, stable, reproducible, and suitable for the practical determination of glucose, sucrose and maltose in compound saccharated pepsin granules.

The volatile compound composition of Pingyao and Yueshengzhai spiced beef was analyzed by simultaneous distillation extraction (SDE) followed by gas chromatography-mass spectrometry (GC-MS). The results indicated that 64 and 65 volatile compounds were identified in Pingyao spiced beef and Yueshengzhai spiced beef, respectively Limonene, ethyl acetate, 2,3-pentanedione, 3-hydroxy 2-butanone, benzaldehyde, benzeneacetaldehyde, tetradecanal, pentadecanal, hexadecanal, ethanol, dihydro-2-methyl-2-3(2H)-furanone, furfural, 5-methyl-2-furan, carboxaldehyde, 1-methoxy-4-(1-propenyl)-benzen and hexadecanoic acid were simultaneously found in both brands of spice beef. The unique compounds of Pingyao spiced beef were (E)-2-octenal, 3,4-dimethyl-benzaldehyde, isopropyl alcohol, 2-butanol, methyl-pyrazine, 2,6-dimethyl-pyrazine, acetic acid, n-decanoic acid and so on. As for Yueshengzhai spiced beef, the unique compounds were 1-methyl-4-(1-methylethyl)-1,4-cyclohexadiene, caryophyllene, 2-heptanone, 3-methyl-6-(1-methylethyl)-2-cyclohexen-1-one, (E)-Cinnamaldehyde, eucalyptol, 3,7-Dimethyl-1,6-octadien-3-ol, 4-Methyl-1-(1-methylethyl)-3-cyclohexen-1-ol, 1-(2-Furanyl)-ethanone.

A high performance liquid chromatography method was presented for the determination of chlorpyrifos-methyl residues in tomato, hot pepper and egg plant. The chlorpyrifos-methyl residues in the samples were extracted into acetonitrile, cleaned up using a Carb/NH2 solid phase extraction column, separated on a C8 liquid chromatography column, and detected with a diode array detector (DAD). The average spike recoveries of the method across three spike levels were between 80.7% and 92.4% (n ＝6), with a relative standard deviation between 1.1% and 4.6%. The detection limit of the method were 0.02 mg/kg.

In this paper, we present a high performance liquid chromatography (HPLC) with differential refractive index detector (RID) method to determine aleuritic acid. Ten mL of the analyte was chromatographically separated on an Agilent ZORBAX SB-C18 column (4.6 mm × 250 mm, 5μm) using a mobile phase consisting of a mixture of methanol and water (60:40, containing 0.1% trifluoroacetic acid) at a flow rate of 1 mL/min. The column temperature was set as 30 ℃. Aleuritic acid showed a good linear relationship over the concentration range of 0.01-1.0 mg/mL with a correlation coefficient of 0.9994. The limit of detection was 0.008 mg/mL. The precision RSD was 0.86% (n ＝9). The average spike recovery rate was 100.23% with a RSD of 0.65% (n ＝ 9). The method was easy to operate, simple, accurate, stable and reliable.

A new method was established for the simultaneous determination of two 5O`- mononucleotides (guanosine monophosphate, GMP; inosine monophosphate, IMP) within one run in soy sauce by high performance capillary electrophoresis. The analysis was performed using an uncoated capillary (50 μm i.d, total length 60.2 cm, and effective length 50 cm). The running buffer was composed of 30 mmol/L Na2B4O7, 30 mmol/L Na2CO3 and 60 mmol/L hydroxypropyl-beta cyclodextrins. The sample medium was 50 mmol/L acetic acid. The detection wavelength was 254 nm. A good linear relationship between the corrected peak area and concentration in the range of 5-100 mg/L were obtained for GMP and IMP with correlation coefficients (r) of 0.9998 and 0.9997, respectively. For both GMP and IMP, the limit of detection (LODs) was 2 mg/L, and the limit of quantification (LOQs) was 5 mg/L. Totally 9 soy sauces commercialized in Beijing were analyzed, and the results were in good agreement with those obtained by high performance liquid chromatography.

The volatile compounds in KFC original recipe fried chicken were analyzed by simultaneous distillation extraction (SDE) and gas chromatography-mass spectrometry (GC-MS). The effect of each compound on the overall flavor was discussed. A total of 66 compounds were identified including 14 hydrocarbons, 23 aldehydes, 4 alcohols, 7 ketones, 4 phenols, 3 acids, 2 esters, 2 lactones and 7 heterocyclic compounds. The prominent compounds were hydrocarbons, aldehydes, acids, ketones and heterocyclic compounds, accounted for 17.44%, 45.41%, 13.26%, 3.65% and 2.79%, respectively.

V. cholerae is well recognized as pathogenic bacteria that cause diseases in both human and aquatic animals. In this study, two pairs of specific primers were designed based on the lolB and toxR genes, and a dulplex polymerase chain reaction (PCR) was established to detect all V. cholerae serogroup and biotypes. The results indicated that both PCR primer pairs could simultaneously amplify 519 bp and 779 bp gene fragments from the chromosomal DNA of V. cholerae. No positive reaction was detected in 4 control strains of pathogenic Vibrio. The sensitivity of the dulplex PCR assay also showed that the designed primer pairs could detect V. cholerae at a level of 3.42 × 103 CFU/mL. The assay was simple, rapid, specific, sensitive and applicable for the detection of V. cholerae for different purposes.

The volatile compounds in pickles produced by inoculated fermentation or natural fermentation were isolated by solid phase micro-extraction (SPME) and analyzed by gas chromatograph-mass spectrometry (GC-MS). The results showed that 60 and 62 kinds of volatile compounds were detected in pickles resulting from inoculated fermentation and natural fermentation, respectively (29 were found in both pickles). In naturally fermented pickle, 16 kinds of esters, 15 kinds of alcohols and 2 kinds of sulfide were detected, accounting for 44.75%, 15.29% and 22.33% of total peak area, respectively. In pickle resulting from inoculated fermentation, 16 kinds of esters, 11 kinds of alcohols and 3 kinds of sulfides were detected, accounting for 48.23%, 5.17% and 33.66% of total peak area, respectively. This study revealed that esters and sulfide were the major compounds in pickles from both fermentation processes and that artificial inoculation resulted in faster fermentation in pickles.

An HPLC-MS/MS (high performance liquid chromatography coupled with tandem mass spectrometry) method has been developed for the determination of isoxaflutole and its two metabolite residues in maize. The isoxaflutole and its metabolite residues in samples were extracted into acetic acid-cetonitrile (1:99, V/V) by means of high-speed homogenization, subjected to liquid-liquid partition in the presence of added anhydrous magnesium sulfate and sodium acetate, cleaned up with primary secondary amine (PSA), octadecylsilane (ODS) and graphitized carbon black for purpose of eliminating such most matrix interferences as lipids, pigments, etc before HPLC-MS/MS analysis and subsequent quantification by an external standard method. The average recovery rates of isoxaflutole and its metabolites from spiked samples ranged between 74.8% and 107.2% with a relative standard deviation of 6.45%－11.15% across the spike levels of 0.010, 0.050 mg/kg and 0.100 mg/kg. The detection limit was 0.01 mg/kg and 0.005 mg/kg for isoxaflutole and its metabolites, respectively. This method was sensitive, accurate, time-saving, simple, and suitable for the detection of isoxaflutole and its metabolite residues in maize.

The aroma components in several Junmei series of Lapsang Souchong black tea such as Jinjunmei, Yinjunmei and Chigan were extracted by solid phase micro-extraction and analyzed by gas chromatography-mass spectrometry (GC-MS). Totally 19, 21 and 20 components were identified in these series, respectively, representing 96.77%, 91.77% and 88.52% of total aroma components, respectively. The major components were phenylethyl alcohol, 3,7-dimethyl-1, 6-octadien-3-ol, benzyl alcohol, hexanal and benzaldehyde.

In order to find out the optimal ripening time for improved taste of chicken during storage, the contents of inosinic acid (IMP) and amino acids in the skeletal muscles from different positions of 20-week-old female and male Menshan chickens were comparatively analyzed by high performance liquid chromatography (HPLC) during storage under different conditions. The results showed that IMP content was dramatically decreased during the first 8 hours of storage at room temperature with the result that the content of hypoxanthine, one of its decomposition products, was significantly increased (P＜0.05). During cold storage at 4 ℃, a slow decrease was observed in IMP content until day 5 followed by a stable trend and hypoxanthine content was significantly increased during day 3－4 (P＜0.05). At both storage temperatures, IMP content was higher in the breast muscle compared with the thigh muscle and the contents of IMP and related nucleotides in the muscle of female chicken were significantly higher than those of male chicken (P＜0.05). The percentage of flavor free amino acids in total amino acids showed a decreasing trend with prolonged storage time. For the thigh muscle, an extremely significantly decrease was observed between the fourth and eighth hours at room temperature and during day 4－5 (P＜0.01) at 4 ℃. In addition, no significant difference was observed between the female and male chickens. In conclusion, the optimal ripening time was 8 h at room temperature and 4 d at 4 ℃ during storage, respectively.

In order to understand the effect of storage temperature on the aromatic components in it, Valencia orange juice was sterilized and stored at 5 ℃, room temperature or accelerated storage temperatures (30, 40 ℃ and 50 ℃). The aromatic components were analyzed after 2, 4 weeks and 6 weeks by solid phase micro extraction-gas chromatography-mass spectrometry method and semi-quantified by internal standard method. The results showed that the important aromatic components that contributes to juice flavor declined, such as limonene, β-myrcene, linalool, octanal, decanal, ethyl butyrate, etc. The contents of five classes of aromatic components decreased slowly after 6 weeks of storage at refrigerated temperature. The contents of hydrocarbons decreased significantly after 6 weeks of storage at accelerated storage temperature; however, no obvious decrease was observed in the contents of alcohols, ketones or esters. The contents of α-terpineol, β-terpineol, furfural and 4-vinylguaiacol, having negative effect on the quality of orange juice, increased comparing with the control group. This study suggests that strict temperature control during storage is necessary to keep the intrinsic aroma of Valencia orange juice and that cold storage is the best choice.

An electrochemical enzyme biosensor was developed to determine hydrogen peroxide in milk. Thionine was electropolymerized on screen-printed electrode, followed by coating the electrode surface with horseradish peroxidase embedded in chitosan-silica sol-gel. The results showed that the response current of the sensor was linearly related to the concentration of hydrogen peroxide in milk samples over the range of 3×10-5 to 1.5×10-3 mol /L with a detection limit of 1.675 ×10-5 mol /L. Recovery rates ranging from 85.6% to 89.4% were obtained in the determination of real samples using the sensor and the results were agreed with those obtained from the Chinese national standard by iodometry method. This method is sensitive, fast and convenient and has potential for applications in the determination of hydrogen peroxide in milk.

The commercial manufacturing technology of peanut tofu was investigated in this study with emphasis on the effects of Ca2+, LA, HA, carrageenan, monoglyceride and cooking temperature on the gel-forming and gel properties of peanut milk. The results of one-factor-at-a-time experiments showed that 0.05% and 0.1% calcium acetate combined with HA or carragheen had little effect on the gelation of peanut milk and its gel properties. However, the addition of 0.2%－0.3% LA had significant influence. The experimental results of orthogonal array design indicated that Ca2+ and HA/LA had significant influence on the gel strength, heat resistance and boiling shock resistance of peanut gels. The best gel quality was achieved when 0.1% Ca2+, 0.2% HA, 0.2% LA, 0.1% carrageenan, and 0.1% monoglyceride were present in peanut milk and cooked at 85 ℃ for 50 min. The commercial process for the production of peanut tofu was established: (1) high-quality peanut milk was emulsified and homogenized, followed by the addition of gelling agent; (2) Ca2+ was added into the mixture when it was heated to 85 ℃; and (3) the mixture was then cooled down, packaged and sealed, and sterilized at 100 ℃ after heating at 85 ℃ for 50 min. The finished product had a satisfied quality and texture profile with a shelf-life of 2 days.