Effect of sterilization and storage on volatile compounds, sensory properties and physicochemical properties of coconut milk

摘要

Sterilization is an important process in beverage production that not only guarantees the edible safety of beverage but also extends its shelf life. However, the quality changes in the coconut milk sterilization and storage has received scarce attention in regard to beverages. Therefore, this study was conducted to investigate the effect of sterilization (at 121 degrees C for 30 min.) and storage (from day 1 to day 19) on the quality of coconut milk. The volatile compounds present in coconut milk were determined by solid-phase microextraction and gas chromatography-mass spectrometry. A total of 31 volatile compounds in coconut milk were tentatively identified, including lactones (34.4%), esters (31.5%), aldehydes (20.0%), acids (3.8%), ketones (2.3%), alcohols (1.4%) and other (0.6%). The relative content of delta-octalactone in lactones had no significant change after sterilization compared with nontreatment, while an increase was observed in the relative content of delta-octalactone from 18.14% to 23.81% in storage. In addition, although the percentage of ethyl octanoate (from 13.15% to 9.05%) in esters significantly decreased after sterilization compared with nontreatment, the content had no significant alter during storage. Those results showed that the volatile compounds in coconut milk changed after sterilization and storage. Further analysis with descriptive sensory evaluation showed that the sensory evaluation ranged from the moderate to extreme levels according to the evaluators. This result indicated that no remarkable change in the sensory qualities of coconut milk by sterilizing and storing. Meanwhile, all attributes had a positive effect on coconut milk, such as overall coconut milk flavor, sweet, nutty. There is no conspicuous affect in the acceptability of coconut milk by evaluators. Overall, these results indicate that sterilization had no significant affect the flavor of coconut milk; moreover, appropriate storage can improve the acceptability of coconut milk before product shipment.