Reuse of UHT Milk Close to Expiring and Almond Okara in the Production of Fresh Cheese

Abstract

This study evaluated the possibility of recycling ultra-high temperature (UHT) milk close to the expiry date in the production of fresh cheese fortified with almond okara, a by-product of almond-based beverage production. The experimental design involved the addition of okara to skimmed and semi-skimmed milk at two different levels of concentration (25% and 50%), obtaining cheese prototypes coded as CS-1/CS-2 and CP-1/CP-2, respectively. The chemical characterization of okara showed a high fiber (13.47 g/100 g) and fat content (18.62 g/100 g), with 90% of lipids composed of polyunsaturated fatty acids (PUFAs). The physicochemical properties and safety of the cheese samples during 30 days of storage were evaluated. Fortification allowed the cheeses to reach the minimum levels for the nutritional claims “source of fiber” (3 g/100 g), “rich in fiber” (6 g/100 g), and “rich in unsaturated fatty acids” (40% of total fats). The addition of okara at 50% level made the cheeses more consistent, with pleasant almond flavor but increased lipid oxidation, even though the oxidative test gave values that did not exceed the limits threshold of toxicological concern (30 µg/kg body weight/day). In addition, the samples obtained with skimmed milk (CS, CS-1, and CS-2) were found to be more consistent and with higher yellow index values than the corresponding formulations obtained with semi-skimmed milk. During storage, all samples showed a reduction in consistency and hardness and an increase in astringent and vegetal flavor, especially for samples containing 50% okara. At the end of the storage period, all cheeses were microbiologically safe.