Effects of replacing buttermilk with yogurt acid whey in ranch dressing.

When products derived from the coagulation of milk are produced, liquid whey results which may account for 80 to 90% of the milk which originally entered the dairy manufacturing facility and about 50% of the milk nutrients. The composition of the whey varies depending on the end product, and the manufacturer’s production process. Hard cheeses (e.g. Cheddar) result in sweet whey, with a relatively high pH (more than 5.8), high protein and low mineral contents. Fresh cheese and strained yogurts ( e.g. Ricotta and Greek yogurt respectively) produce acid whey, with a much lower pH (3.5 to 5), lower protein, and higher mineral content. The high biological oxygen demand of whey makes its disposal into water streams or municipal waters problematic. Its acidity and nutrient content disrupt the natural equilibrium of stagnating waters, leading to algae blooms and loss of aquatic life. Whey disposal is therefore tightly regulated and dairy manufacturers must find alternative ways of disposal. In the case of sweet whey, innovative processing techniques have been developed for the extraction of lactose and protein to be up-scaled as value-added ingredients. In the case of yogurt acid whey (YAW), its limiting physico-chemical characteristics, mainly low pH and lack of protein, have posed significant challenges that constraint its spray-drying and restricted application for concentration and nutrient extraction. Thus YAW disposal is a costly process. These limitations have caused YAW to be directed mostly toward non-food uses, and valuable nutrients of acid whey remain predominantly outside of the human consumption channel. If YAW can de shifted from a costly waste by-product to a valuable ingredient it would be a financial achievement for the dairy industry, as well as an indispensable permanent solution to the dairy pollution problem. Thus, work on the extent to which liquid YAW can be used as an ingredient is essential, both in terms of the maximum acceptable concentration that can be applied to different product categories, as well as any required processing adjustments. In the study by Dr J.C. Flinois and colleagues, they evaluated the feasibility of formulating ranch dressing by replacing buttermilk with YAW. Their results were published in the Journal of Dairy Science, Volume 102 of 2019, page 7874 to 7883, the title being: Effects of replacing buttermilk with yogurt acid whey in ranch dressing. 

A shelf-stable ranch dressing was formulated by replacing buttermilk in the control with YAW and concentrated YAW (6.3 to 25.2 °Brix). Added salt, gums and acids were adjusted. The effects of buttermilk substitution on stability were studied on pasteurized samples (8 months at room temperature). A consumer sensory study was conducted utilizing hedonic and just-about-right scales. Purchase intent and demographic data were also collected. A focus group evaluated the sensorial attributes of the samples after 6 months. The experiment was performed in triplicate and all instrumental analyses (pH, soluble solids as °Brix, water activity, refraction index, and colour) were conducted in triplicate for statistical analysis.

By increasing the gum content in the YAW samples an equivalent texture liking compared with the control resulted. By matching the control’s NaCl (salt) concentration undesirable higher saltiness resulted. The pH of the 18.9 °Brix YAW ranch sample without lactic acid added was under 4.6, with no effect on flavour liking. By increasing the concentration of YAW, L* and water activity were decreased and the refractive index and hue were increased. The YAW samples presented minimum changes over 8 months of storage and had better water retention than the control. The optimal replacement of buttermilk inthe dressing was 15 to 17 °Brix YAW. 

It was concluded that the formulation of dressings may be accomplished successfully, sustainably and cost effectively, with minor processing adjustment, by substituting buttermilk with YAW.