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Molecules

Title:		"Shelf-Life Stability of Ready-to-Use Green Rooibos Iced Tea Powder-Assessment of Physical, Chemical, and Sensory Properties"
Author(s):		Human C; de Beer D; Muller M; van der Rijst M; Aucamp M; Tredoux A; de Villiers A; Joubert E;
Address:		"Plant Bioactives Group, Post-Harvest and Agro-Processing Technologies, Agricultural Research Council (Infruitec-Nietvoorbij), Private Bag X5026, Stellenbosch 7599, South Africa. Department of Food Science, Stellenbosch University, Private Bag X1, Stellenbosch 7600, South Africa. Biometry Unit, Agricultural Research Council, Private Bag X5026, Stellenbosch 7599, South Africa. School of Pharmacy, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa. Department of Chemistry and Polymer Science, Stellenbosch University, Private Bag X1, Stellenbosch 7600, South Africa"
Journal Title:		Molecules
Year:		2021
Volume:		20210830
Issue:		17
Page Number:		-
DOI:		10.3390/molecules26175260
ISSN/ISBN:		1420-3049 (Electronic) 1420-3049 (Linking)
Abstract:		"Green rooibos extract (GRE), shown to improve hyperglycemia and HDL/LDL blood cholesterol, has potential as a nutraceutical beverage ingredient. The main bioactive compound of the extract is aspalathin, a C-glucosyl dihydrochalcone. The study aimed to determine the effect of common iced tea ingredients (citric acid, ascorbic acid, and xylitol) on the stability of GRE, microencapsulated with inulin for production of a powdered beverage. The stability of the powder mixtures stored in semi-permeable (5 months) and impermeable (12 months) single-serve packaging at 30 degrees C and 40 degrees C/65% relative humidity was assessed. More pronounced clumping and darkening of the powders, in combination with higher first order reaction rate constants for dihydrochalcone degradation, indicated the negative effect of higher storage temperature and an increase in moisture content when stored in the semi-permeable packaging. These changes were further increased by the addition of crystalline ingredients, especially citric acid monohydrate. The sensory profile of the powders (reconstituted to beverage strength iced tea solutions) changed with storage from a predominant green-vegetal aroma to a fruity-sweet aroma, especially when stored at 40 degrees C/65% RH in the semi-permeable packaging. The change in the sensory profile of the powder mixtures could be attributed to a decrease in volatile compounds such as 2-hexenal, (Z)-2-heptenal, (E)-2-octenal, (E)-2-nonenal, (E,Z)-2,6-nonadienal and (E)-2-decenal associated with 'green-like' aromas, rather than an increase in fruity and sweet aroma-impact compounds. Green rooibos extract powders would require storage at temperatures
Keywords:		Aspalathus/*chemistry Beverages/analysis Tea/chemistry Volatile Organic Compounds/chemistry aspalathin beverage powder rooibos iced tea sensory profile storage stability volatile compounds;
Notes:		"MedlineHuman, Chantelle de Beer, Dalene Muller, Magdalena van der Rijst, Marieta Aucamp, Marique Tredoux, Andreas de Villiers, Andre Joubert, Elizabeth eng 93438/National Research Foundation/ 96711/National Research Foundation/ Switzerland 2021/09/11 Molecules. 2021 Aug 30; 26(17):5260. doi: 10.3390/molecules26175260"