PhD Thesis abstract published online as a service to the JDR Community.
Ingredient supplementation effects on acid whey production and quality of Greek Style yogurt
Rabin Gyawali
Rabin Gyawali
Abstract
Greek or Greek style yogurt (GSY) is known as strained or concentrated form of yogurt where milk total solids increased after drainage of acid whey (AW). GSY production generates large amounts of AW as a by-product. This AW has limited applications. Thus, processing and utilization of AW is one of the main concerns for the dairy industry. It is a common industrial practice to incorporate ingredients such as polysaccharides and milk proteins for the manufacture of yogurt. The objective of this study was to investigate the effects of different ingredients on AW production and quality of GSY. GSY were prepared using low fat milk base (0, 1, & 2%) fortified with different ingredients. Yogurts were fermented at different temperature (37, 40, & 43°C) with three different yogurt culture (Greek yogurt starter culture, FD-DVS YC-380 and F-DVS YoFlex Premium 1 culture) blend of L. bulgaricus and S. thermophillus for ~ 4 h then refrigerated at 5°C. AW production was measured by calculating the water holding capacity (WHC). Our results showed that pectin (0.05%) and whey proteins (1%) significantly reduced the AW compared to the control sample (p <0.001). The WHC of the yogurts fermented at 40°C were 24%, 23%, and 18% higher than control sample in yogurt made with 0, 1, and 2% milk fat respectively. After 28 days of storage, WHC for fortified yogurt was 66% compared to 45% in control yogurt. During the storage L. bulgaricus population decreased by1.0 log CFU/g whereas there was no reduction in S. thermophilus population as compared to the initial count. When yogurts were fermented with YC-380 and Premium-1 culture under the same conditions, similar trend in bacterial population was observed. For both culture types, there was ~ 20% higher WHC in yogurt compared to the control sample at the end of storage period. Textural studies showed pectin-WPC yogurt had higher viscosity compared to yogurt fortified with pectin, WPC alone and control. Our results demonstrated that GSY can be formulated and manufactured by the addition of pectin and whey protein concentrate (WPC) as stabilizer. These ingredients can reduce AW and could be industrially applicable for the production of GSY. Moreover, this approach could help address the problem of AW disposal and promote the viable GSY production.
Greek or Greek style yogurt (GSY) is known as strained or concentrated form of yogurt where milk total solids increased after drainage of acid whey (AW). GSY production generates large amounts of AW as a by-product. This AW has limited applications. Thus, processing and utilization of AW is one of the main concerns for the dairy industry. It is a common industrial practice to incorporate ingredients such as polysaccharides and milk proteins for the manufacture of yogurt. The objective of this study was to investigate the effects of different ingredients on AW production and quality of GSY. GSY were prepared using low fat milk base (0, 1, & 2%) fortified with different ingredients. Yogurts were fermented at different temperature (37, 40, & 43°C) with three different yogurt culture (Greek yogurt starter culture, FD-DVS YC-380 and F-DVS YoFlex Premium 1 culture) blend of L. bulgaricus and S. thermophillus for ~ 4 h then refrigerated at 5°C. AW production was measured by calculating the water holding capacity (WHC). Our results showed that pectin (0.05%) and whey proteins (1%) significantly reduced the AW compared to the control sample (p <0.001). The WHC of the yogurts fermented at 40°C were 24%, 23%, and 18% higher than control sample in yogurt made with 0, 1, and 2% milk fat respectively. After 28 days of storage, WHC for fortified yogurt was 66% compared to 45% in control yogurt. During the storage L. bulgaricus population decreased by1.0 log CFU/g whereas there was no reduction in S. thermophilus population as compared to the initial count. When yogurts were fermented with YC-380 and Premium-1 culture under the same conditions, similar trend in bacterial population was observed. For both culture types, there was ~ 20% higher WHC in yogurt compared to the control sample at the end of storage period. Textural studies showed pectin-WPC yogurt had higher viscosity compared to yogurt fortified with pectin, WPC alone and control. Our results demonstrated that GSY can be formulated and manufactured by the addition of pectin and whey protein concentrate (WPC) as stabilizer. These ingredients can reduce AW and could be industrially applicable for the production of GSY. Moreover, this approach could help address the problem of AW disposal and promote the viable GSY production.
Affiliation and Awarding Institution: North Carolina Agricultural and Technical State University Greensboro, NC, 27411 USA
Corresponding E-mail address: rgyawali@gmail.com
Availability of full Thesis: please contact author
Corresponding E-mail address: rgyawali@gmail.com
Availability of full Thesis: please contact author
Abstract published 15 January 2021.
