OBJECTIVE: The changes in phenolic compound profiles of green, white, and black tea (GT, WT, & BT respectively) water extracts and their respective yogurt were investigated.
METHODS: Three types of yogurt with tea water extracts were prepared, and the phenolic compound profiles were analyzed using the liquid chromatography-mass spectrometry (LC-MS) method.
RESULTS: The present data found that flavonol glycosides such as kaempferol-3-rutinoside and quercetin-rhamnosylgalactoside or rutinoside were present in WT extract, whereas catechin derivatives such as gallocatechin (GC) and epigallocatechin (EGC) were present in GT extract. Moreover, theaflavin-3-O-gallate was observed in BT extract. Many of the catechin and its derivatives detected in the tea extracts were not identified in the tea yogurt samples. However, new phenolic compounds were present in GT-yogurt (i.e., kaempferol-3-rutinoside and quinic acid conjugate) but absent in GT extract.
CONCLUSION: GT, WT, & BT extracts could be used to enriched-yogurt with phenolic compounds, which may have antioxidant properties.
RESULTS: Increases in homogenization pressure and emulsifier concentration were observed to have significant (P 0.05) differences between the prepared and commercial LNDCs in terms of their color, appearance, and overall acceptability.
CONCLUSION: Shelf-stable LNDCs with qualities comparable to commercial LNDC were successfully fabricated. Valuable insights into the effects of homogenization pressure, oil type, and emulsifier concentration, as well as functionality and consumer acceptance of the LNDCs when added into black coffee, were obtained. © 2020 Society of Chemical Industry.
RESULTS: A novel α-amylase (AmyA1) containing an open reading frame of 1482 bp was cloned from Antarctic psychrotolerant fungus G. pannorum and then expressed in the newly constructed Aspergillus oryzae system. The purified recombinant AmyA1 was approximate 52 kDa. AmyA1 was optimally active at pH 5.0 and 40 °C, and retained over 20% of maximal activity at 0-20 °C. The K m and V max values toward soluble starch were 2.51 mg/mL and 8.24 × 10-2 mg/(mL min) respectively, with specific activity of 12.8 × 103 U/mg. AmyA1 presented broad substrate specificity, and the main hydrolysis products were glucose, maltose, and maltotetraose. The influence of AmyA1 on the quality of bread was further investigated. The application study shows a 26% increase in specific volume, 14.5% increase in cohesiveness and 14.1% decrease in gumminess in comparison with the control. AmyA1 was immobilized on magnetic nanoparticles and characterized. The immobilized enzyme showed improved thermostability and enhanced pH tolerance under neutral conditions. Also, magnetically immobilized AmyA1 can be easily recovered and reused for maximum utilization.
CONCLUSIONS: A novel α-amylase (AmyA1) from Antarctic psychrotolerant fungus was cloned, heterologous expression in Aspergillus oryzae, and characterized. The detailed report of the enzymatic properties of AmyA1 gives new insights into fungal cold-adapted amylase. Application study showed potential value of AmyA1 in the food and starch fields. In addition, AmyA1 was immobilized on magnetic nanoparticles and characterized. The improved stability and longer service life of AmyA1 could potentially benefit industrial applications.