Consumption of milk and dairy products has a significant role in people's diet. Milk is full of complex nutrient and colloid compound that mainly consists of water, fat, protein, lactose, vitamins, and minerals. Waste is materials that remain unusable in the conversion industry after using the raw material to produce the desired product. Due to the increasing number of dairy products and their diversity, the control of waste and energy in dairy factories is of great importance. During the butter production, whit the cream working and stirring operation, a substance called buttermilk comes out of the buttering machine. Buttermilk is one of the by-products of dairy factories that is considered as a by-product and low value during production, but recently it has been used due to its functional food in the production and enrichment of some dairy products such as cheese. Buttermilk is often discarded or not used of this in dairy factories. Buttermilk has a high nutritional value, contains nutraceutical compounds such as MFGM, and contains 8.75% of solids, that 2.58% are proteins and 1.2% are lipids. There are different types of buttermilk, including sweet-cream buttermilk, sour-cream buttermilk, and buttermilk whey. Depending on the production of butter from sour or sweet cream, the resulting waste buttermilk can be sour (lactic) or sweet. On an industrial scale, with the assistance of the spray-drying process, buttermilk can be turned into powder, and shelf life extended. Cheese is one of the most widely consumed and varied dairy products in the world produced from various livestock milk. Membrane technology is a broad term for several molecular separation processes. Reverse osmosis and ultrafiltration membrane systems are two of the most common membrane processes in the dairy industry. This study aimed to enrich ultrafiltrated feta cheese with Sweet and lactic buttermilk powders and to investigate its physicochemical and sensory properties during storage. Some physicochemical properties including moisture, ash, fat, protein, non-protein nitrogen, dry matter, oxidation of the product during storage were investigated. Also, textural properties, synergies, color, and sensory properties were eva‎luated. Non-protein moisture and nitrogen as an indicator of proteolysis and oxidation indicators such as peroxide number and the thiobarbituric acid number increased with increasing concentration of buttermilk in ultrafiltrated feta cheeses during storage. Synersies, ash, protein, and fat in produced cheeses also decreased over time. Acidity increased until mid-storage, then decreased amount. The results of sensory eva‎luation also showed an improvement in the aromatic and flavor properties of feta cheeses if enriched with buttermilk, especially lactic buttermilk.

علي نصيرپور، جواد كرامت

مرجان فروغي

مهدي كديور، اسماعيل مهريار