Effects of different thawing methods on flavor compounds and sensory characteristics of raspberry

In order to identify more suitable thawing method to preserve aroma, taste, and other sensory quality of raspberry, five thawing methods were used to treat frozen raspberry, namely water bath thawing, microwave thawing, ultrasonic thawing, room temperature thawing, and refrigeration thawing. Gas chromatography-mass spectrometry was employed to study the quantitative and qualitative analysis of the volatile compounds, and the characteristic flavor components of raspberry were compared by relative odor activity value (ROAV). Electronic tongue technique and fuzzy comprehensive evaluation were used to ensure the changes in sensory qualities of raspberry. The results showed that the time of microwave thawing was 0.57 minutes, and drip loss was 4.40%. Both of them were the lowest among the five thawing methods. The volatile components of raspberry included aldehydes, esters, ketones, alcohols, fatty acids, terpenes, and other compounds. Among them, there were 19 kinds of volatile components in quick-frozen raspberries, 18 volatile components in raspberries after treated by microwave thawing and refrigeration thawing, 16 volatile components after room temperature thawing, 12 volatile components after ultrasonic thawing, and 10 volatile components after water bath thawing. The characteristic flavor compounds of raspberry were identified as acetaldehyde, alpha-ionone, beta-ionone, raspberry ketone, alpha-terpene, and alpha-pinene. Microwave thawing was the most suitable way to preserve the characteristic flavor components of raspberry, but water bath thawing could destroy the most of compounds. After microwave thawing, raspberry tasted best and was most acceptable to consumers. Therefore, microwave thawing was the most appropriate method to preserve raspberry flavor and sensory quality among the five thawing methods.