Enhancing dairy sustainability: Rheological, sensory, and physical-chemical properties of low-fat fermented beverages incorporating buttermilk

Buttermilk is a co-product of butter manufacturing, possessing techno-functional, nutritional, and functional properties. However, it is often discarded or underutilized by the dairy industry, particularly in developing countries. The objective of this study was to develop five formulations of low-fat fermented dairy beverages by varying the ratios of skim milk and buttermilk: F1 (100 % skim milk); F2 (75 % skim milk, 25 % buttermilk); F3 (50 % skim milk, 50 % buttermilk); F4 (25 % skim milk, 75 % buttermilk); and F5 (100 % buttermilk). These formulations underwent analyses for centesimal composition, pH, syneresis, water holding capacity, microbiology, rheology, and sensory evaluation. The substitution of milk with buttermilk did not impact the centesimal composition and pH ((pH) over bar = 4.48) of the beverages. Furthermore, the inclusion of 25 % buttermilk reduced whey separation by similar to 3 % on the day of production and increased the water holding capacity from 58.89 % to 62.72 % of the beverages during 16 days of storage. All formulations presented non-Newtonian pseudoplastic behaviour and apparent viscosity at 50 s(-1) from 0.85 to 1.17 Pa s (at 5 degrees C) and 0.57-0.98 Pa s (at 25 degrees C). F4 and F5 presented lower gel strength compared to the other treatments. Among the formulations, F3 demonstrated favorable acceptance (global impression = 7.47) and a positive inclination towards the purchase (2.27), with no significant difference from the sample containing 100 % milk (F1). However, the Rate-All-That-Apply test revealed that sensory attributes characteristics of butter, such as flavour, aroma, and greasiness, negatively affected the acceptance of beverages with higher concentrations of buttermilk (F4 and F5). Consequently, utilizing buttermilk as a partial substitute (<= 50 %) for milk proved to be a viable alternative to produce nutritious, sensory-pleasing, and cost-effective food items, thereby bolstering the bio-economy in the dairy chain.