MEMBRANE PROCESSING STRATEGIES FOR VALUE-ADDED UTILIZATION OF ACID WHEY FROM GREEK-STYLE YOGURT
As we move into the Anthropocene, sustainability is achieving the status of a survival necessity. The food-water-energy nexus is as strained as ever, requiring thoughtful and innovative changes from all facets of human activity. In the center of this conundrum is the food supply chain, which is currently full of unsustainable practices. Food manufacturers represent part of this chain, and some solutions are already starting to show up on that front. They include the reuse and upcycling of by-products and coproducts typically regarded as waste, turning them into new, sustain-able, value-added products. Food processing is also going through a major change with the growing implementation of nonthermal technologies that could lead to the production of fresh, nutritious, safe foods while minimizing the consumption of en-ergy and water. The dairy industry is sometimes criticized for not always having the most sustainable practices. One example is the issue of Acid Whey, an abundant and chal-lenging coproduct from the Greek-style yogurt manufacturing which can pose a sig-nificant environmental impact if improperly disposed of. In Chapter One of this dissertation, sustainability is defined in the context of the food supply chain, ranging from production to processing to food waste and loss at the consumer end. Some examples of sustainable and unsustainable practices are presented and discussed, and so is a quantitative tool for holistically assessing the sustainability of a food product. Chapter Two delves into an extensive characterization of Acid Whey and Milk Permeate. In summary, they show low protein contents and pH, and high miner-al amounts and Biochemical Oxygen Demands. This characterization can contribute to a database of properties that could help in finding a better destination for such streams. Based on the composition of Acid Whey, two different nonthermal membrane strategies for the value-added utilization of this coproduct were studied and are pre-sented in detail in this dissertation. In Chapter Three, the fractionation of some of the components in Acid Whey was investigated using a combination of cold Micro-filtration and Ultrafiltration. This was shown to be feasible only when there was enough protein in the material, which is seldom the case. Therefore, Chapter Four proposes the concentration of Acid Whey using a combination of Reverse Osmosis and Forward Osmosis. The process developed can produce concentrates comparable with those obtained by thermal evaporation, but without thermal damage to their components, and at a lower energy consumption. Lastly, Chapter Five contains an empirical model to predict the flux during the Forward Osmosis of Acid Whey given the desired concentration and operating temperature. The information contained in this dissertation could help food manufac-turers make more informed decisions about how to handle Acid Whey and other challenging byproducts, including using nonthermal alternatives such as Forward Osmosis for the concentration of challenging or sensitive liquid food products.
Food science; forward osmosis; nonthermal; Acid Whey; reverse osmosis; membrane processing; sustainability
Moraru, Carmen I.
Gao, Huaizhu; Novakovic, Andrew Milovan
Food Science and Technology
Ph.D., Food Science and Technology
Doctor of Philosophy
dissertation or thesis