Abstract:

Guanxi honey pomelo fruits were immersed in ice-water (0 ℃) for 0 (CK), 0.5 (L0.5h), 1 (L1h), 1.5 (L1.5h) and 2h (L2h), and then stored at room temperature for 166 days to evaluate the effect of cold shock pre-treatment on product quality during storage. Juice rate, edible rate, total soluble solids (TSS), total sugar (TS), total acids (TA), malondialdehyde (MDA), ascorbic acid (AA), catalase activity (CAT) and relative permeability of plasma membrane (RPPM) were analyzed. Results indicated that relative conductivity of the cold shock treatment group was lower than that of cold shock control group (0.44), and the relative conductivity of the L1h group was the lowest (0.35). TS content in L1h group was the highest (2.83 g/10 g) and then followed by L0.5h group (2.37 g/10 g), which was higher than CK group by 31.6% and 10.2%, respectively. MDA content in L1h group was the lowest, which was 0.81-fold of CK and next was in L0.5h group with 0.83-fold of CK. Edible rate in L1h group was the highest (72.8%) and next was in L0.5h group (2.37 g/10 g), which was higher than 5.2% and 3.6% of CK, respectively. CAT activity in L1h group remained the highest level, which was 1.12-fold of CK group and next was in L0.5h group, which was 1.03-fold of CK. AA content was totally higher than CK, and the order from high to low was L1.5h, L0.5h, L2h, L1h and CK. Short time cold shock could alleviate the reduction of juice rate and maintain a higher TA content. The juice rates were 76.4 % and 75.6% in L0.5h and L1h groups, which were higher than CK group (75.1%). TA content in L1h group (168.3 g/kg) was the highest level with 19.2% higher than CK group and next was in L0.5h group (155.5 g/kg) with 10.0% higher than CK. TSS content was a little higher than or close to CK group. In a word, cold shock pretreatment can improve the product quality of Guanxi honey pomelo fruits during storage at room temperature and immersion in ice-water for 1 h has the best effect.