Abstract
Whey, liquid wastewater from cheese production, is one of the sources of dietary protein and lactose that are still largely unused for human consumption. It is only in recent years that it has aroused the interest of industries and sought as a valuable raw material and thus represents an opportunity for the manufacture of new products. The manufacture of fermented whey drink requires the mixing of whey with fruit juice or an aromatic plant to improve its organoleptic properties and acceptability. Myrtle, an aromatic medicinal plant, known for its health benefits is not well exploited for making dairy products. This is the first report on the development of kefir-myrtle beverage. Three factors were optimized (whey permeates (%), myrtle’s juice (%), and kefir grains as inoculum (%)) using a central composite design with response surface methodology. The analyses showed that the number of lactic acid bacteria (LAB) and yeast cells varied from 5.4 to 9.2 log10 CFU/mL and from 4.3 to 6.2 log10 CFU/mL, respectively. A decrease in pH and an increase in the total polyphenol content and antioxidant activity were observed. The analysis of variance indicated the goodness of fit of the model with R2 from 0.827 to 0.966. The absolute average deviation values of each model were low and ranged from 1.61% to 4.23%. The optimized fermented kefir whey beverage accomplished an overall acceptability of 5.41 (1 to 9 preference scale) and a high number of LAB cells (8.53 log10 CFU/mL). The viability of LAB and yeast cell was maintained at 7.61 and 6.19 log10 CFU/mL, respectively, after 14 days of storage.
Highlights
Introduction e dairy industry inTunisia is one of the important food industries in the country. is sector comprises 25 enterprises that processed daily about 3.8 million liters, and 13% of the total volume of produced milk is destined for cheese production [1]
Optimization was done by a central composite design (CCD) to determine the optimum ratio of whey permeate, myrtle juice, and kefir inoculum on pH, lactic acid bacteria (LAB), and yeast viability, % radical scavenging activity, polyphenol content, and overall acceptability
Kefir grains (KG) used in this study were collected from Tunisian households and preserved by the laboratory of microbial ecology and microbial technology (LETMi, Institute of Applied Sciences and Technology (INSAT)) [11, 20]. e grains were cultured in sterile cow milk and renewed daily to maintain their viability
Summary
Received 7 August 2021; Revised October 2021; Accepted October 2021; Published 12 November 2021. Since lactose is the main component of whey solids, various biotechnological processes have been developed to use whey as a substrate to produce important industrial products having functional properties It can be Journal of Chemistry converted into prebiotic such as galactooligosaccharides (GOS), lactulose, lactobionic acid, and tagatose [5]. Optimization was done by a central composite design (CCD) to determine the optimum ratio of whey permeate, myrtle juice, and kefir inoculum on pH, lactic acid bacteria (LAB), and yeast viability, % radical scavenging activity, polyphenol content, and overall acceptability. From this design, the surface plots of considered responses with respective second-order polynomial models were obtained. The analysis of variance (ANOVA) was employed to judge the adequacy of the model, and the optimized formulation was validated experimentally
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