Influence Of Back Bean/Macadamia Ratios And Storage Duration On The Quality Of Mixed Milk And Application Of The Milk In Kefir Making

Abstract

This specific study observed the effect of green-kernel black bean milk (BM) fortification on control macadamia milk (CM) with different ratios (% BM/% MM: 10/90, 20/80, 30/70, 40/60, 50/50) for the development of a new healthy plant-based beverage. In order to study the effects of different black bean-macadamia ratios and storage duration on the quality of mixed milk and product stability for the application in kefir making, samples were analyzed for product qualities including moisture, ash, protein, lipid, and carbohydrate content, along with recordings of pH, density, solids content, and acceptability of the final products. The use of BM in mixed milk production positively affected the physical stability, and increasing BM concentration led to an increase in the total protein, carbohydrate and solids content. All ratios were found to be equally favored in view of sensorial quality. Additionally, thiobarbituric acid reactive substance (TBARS) assay and peroxide value (PV) test were performed to measure the extend of lipid oxidation within milk samples after 7-day refrigeration. Both tests showed that increasing BM percentage decreased the sensitivity towards oxidation of macadamia milk with high unsaturated fatty acid composition, hence, descended the level of lipid degradation at the end of storage period. Furthermore, this study also aimed to assess the proximate composition, physicochemical characteristics and acceptability of control macadamia kefir and mixed milk kefir beverages. Correspondingly was conducted a comparison between these two types of kefir in order to conclude that BM-added kefir had higher protein, carbohydrate, total solids, WHC, with lower fat, acidity, and close to none significant sensorial differences when compared to the control kefir. Similarly, when being in comparison with the initial milk samples, selected kefir samples showed a drop in macronutrient content, pH and Brix values, which related to the fermentation stage. Overall, the study confirmed that the combination of oily nuts and protein-dense legumes as a new formula of healthy plant milk was potentially effective in preserving the quality of nut milk product during prolonged storage as well as development of following kefir beverage.