FOOD SCIENCE ›› 2019, Vol. 40 ›› Issue (8): 87-93.doi: 10.7506/spkx1002-6630-20180423-290

• Bioengineering • Previous Articles     Next Articles

Process Optimization for Production of Fermented Apple Pulp with Probiotics and Analysis of Volatile Flavor Components before and after Fermentation

REN Tingting, YUE Tianli, WEI Xin, WANG Xuan, YUAN Yahong   

  1. College of Food Science and Engineering, Northwest A&F University, Yangling 712100, China
  • Online:2019-04-25 Published:2019-05-05

Abstract: The fermentation conditions for the production of fermented apple pulp with a probiotic mixture were optimized and the change of volatile flavor components was investigated before and after fermentation. Lactobacillus plantarum 21805 and Lactobacillus acidophilus 20250 were selected for use as mixed starter culture. The effects of inoculum composition and amount, fermentation temperature, fermentation time, sterilization conditions, and apple pulp-to-water ratio on the quality of fermented apple pulp as evaluated by viable bacterial count and sensory score were studied. One-factor-at-atime and orthogonal array design methods were used to optimize the fermentation conditions. Head-space solid phase micro-extraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) was used to analyze the volatile flavor components. The results showed that the optimum fermentation conditions were determined as follows: fermentation temperature 32 ℃, fermentation time 36 h, inoculum amount 2%, L. plantarum 21805 to L. acidophilus 20250 ratio 4:1, apple pulp to water ratio 2:1 (g/mL), and sterilization at 100 ℃ for 15 min. The flavor of the fermented apple pulp produced under the optimized was good, and the viable bacterial count reached 8.93 (lg (CFU/mL)). A total of 27 volatile flavors were detected in the fermented apple pulp, including 6 alcohols, 10 esters, 5 ketones, and 2 aldehydes. Apple pulp produced 15 new volatile flavors after fermentation. The relative contents of esters, alcohols and ketones increased after fermentation, while aldehydes showed a decreasing trend. Hierarchical cluster analysis (HCA) indicated that the volatile flavor composition of apple pulp was significantly changed after fermentation.

Key words: probiotics, apple pulp, fermentation, flavor, head-space solid phase micro-extraction (HS-SPME), gas chromatography-mass spectrometry (GC-MS)

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