Dairy waste by-products: An updated Review

The dairy sector plays an important major role in the food industry, providing essential products such as milk, cheese, butter, yogurt, and milk powder to meet the global population's needs. Dairy waste can be broadly classified into 2 groups mainly liquid waste (whey, washed water, cleaning agent), and solid waste (Expired milk and milk products, packaging material, sludge) which can further be categorized into edible by-product waste (cheese whey, buttermilk, yoghurt whey, cream residue) and non-edible dairy waste (Packaging material, sludge, dairy scum, untreated water, cleaning agent, spoiled milk). These wastes can be a substrate for large scale production of biomass, biopolymer and generating energy using integration of technologies. The wastewater contains high organic load due to presence of carbohydrates, protein, and fats that come from milk. Microbial valorization strategies like fermentation, enzymatic hydrolysis and biosynthesis can be used to produce a large variety of value-added bio-products like biofertilizers, biopolymers, biofuels, biosurfactants, bioactive compounds, organic acids, enzymes and others. Therefore, valorizing dairy waste into useful products presents a significant advantage for the dairy industry.