Optimization of Parameters Using Response Surface Methodology to Develop a Novel Kefir-Like Functional Beverage from Cheese Whey Enriched with Myrtle Juice

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.

Multi-Objective Optimization of Beverage Based on Lactic Fermentation of Goat’s Milk Whey and Fruit Juice Mixes by Kefir Granules

“…pH and • Brix were determined at the beginning and end, observing a drop of both pH and • Brix for all treatments (result not shown). This fact indicates that in all treatments, the microbial population grows and has been observed by other researchers [32,53,54]. Furthermore, there is a positive Pearson correlation between the relative decrease in pH and • Brix with the values reached for LAB (r = 0.81) and yeast (r = 0.66) growth.…”

“…Surprisingly, in two of the combinations ('OPT1' and 'OPT2'), where a better behavior was observed (with values of D = 0.8), there were those where only the WKG was used, even though in one of them ('OPT1'), the substrate mixture used contained >70% GMW. The LAB values achieved were 8-fold higher than those reported by Sabokbar and Khodaiyan [58] and 3.8-fold higher than those reported by M'Hir et al [32], while for yeasts, they were 2270-fold higher than those reported by Sabokbar and Khodaiyan [58], and 280-fold higher than those reported by M'Hir et al [32].…”

“…Other researchers have also used mixtures of cow's milk whey with juices to improve their fermentation products' nutritional and sensory properties with kefir grains [32,[56][57][58][59].…”

“…In another example, a functional fermented beverage was obtained using whey cheese enriched with myrtle (Myrtus communis) juice. As a result, values of 3.40 × 10 8 CFU/mL for LAB, 1.62 × 10 6 CFU/mL for yeasts and global acceptability (on a 9-point scale) of 5.41 ± 0.12, under optimal conditions using a central composite design in the response surface methodology, were obtained [32].…”

“…The use of milk-or water-kefir grains (MKG and WKG) have been used as starters for the fermentation processes of substrates such as milk [27,28], and whey [12], herbal teas [29], vegetable juices [30], and fruit juices [31,32]. Numerous reports indicate the health benefits of beverages fermented with these granules [17,26,[33][34][35][36][37].…”