Effects of high‐power ultrasound on microflora, enzymes and some quality attributes of a strawberry drink

• Published in: Journal of the science of food and agriculture Vol. 98; no. 14; pp. 5378 - 5385
• Main Authors: Chen, Liyi, Bi, Xiufang, Cao, Xiamin, Liu, Lei, Che, Zhenming
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01-11-2018; John Wiley and Sons, Limited
• Subjects: Aerobic bacteria; Aerobic capacity; Anthocyanins - analysis; Antioxidants; Antioxidants - analysis; Bacteria - classification; Bacteria - genetics; Bacteria - growth & development; Bacteria - isolation & purification; Berries; Beverages; Browning; Carboxylic Ester Hydrolases - analysis; Catechol Oxidase - analysis; Color; Enzymes; Esterase; Food Handling - instrumentation; Food Handling - methods; Fragaria - chemistry; Fragaria - enzymology; Fragaria - microbiology; Fruit - chemistry; Fruit - growth & development; Fruit and Vegetable Juices - analysis; Fruit and Vegetable Juices - microbiology; Glucosidase; high‐power ultrasound; Microflora; Nutrients; Organic chemistry; Pasteurization; Pectin; Phenols; Plant Proteins - analysis; Polyphenol oxidase; Quality management; strawberry drink; Turbidity; Ultrasonic imaging; Ultrasonics - methods; Ultrasound; Viscosity; Yeasts; β‐glucosidase; color; β-glucosidase; high-power ultrasound; strawberry drink; microflora
• ISSN: 0022-5142; 1097-0010
• DOI: 10.1002/jsfa.9079

BACKGROUND
The objective of the present work was to study the effect of high‐power ultrasound (HPU) on the microflora, enzymes and some quality attributes of a strawberry drink and to provide a theoretical basis for strawberry drink processing conducive to the development of more nutritious and healthier strawberry drinks.
RESULTS
Fresh strawberry drink was subjected to HPU treatment at 20 kHz (242, 605 and 968 W cm−2) for 2, 4, 6, 8 and 10 min in an ice bath. Results showed that polyphenol oxidase (PPO), pectin methyl esterase (PME) and β‐glucosidase activities were decreased by 44.90, 89.11 and 84.71% respectively at 968 W cm−2 for 10 min. Lower L*, a* and b* values and higher browning degree (BD) were observed in HPU‐treated samples, resulting in a significant increase in ΔE value (P < 0.05). HPU treatment caused loss of viscosity and turbidity, while total soluble solids (TSS) and pH of the strawberry drink were stable. Total phenol content and antioxidant capacity increased while anthocyanin content decreased compared with untreated samples. Total aerobic bacteria (TAB) and molds and yeasts (M&Y) were reduced by 2.07 and 1.13 log10 cycles respectively at 968 W cm−2 for 10 min.
CONCLUSIONS
HPU can effectively achieve the effect of pasteurization and maintain the nutrients of strawberry drink. © 2018 Society of Chemical Industry