Screening of frozen-thawed conditions for keeping nutritive compositions and physicochemical characteristics of goat milk

Frozen milk can help producers overcome the seasonality of goat production, low production and short lactation periods, avoid discarding during some special periods. We investigated effects combination between freezing (cryogenic refrigerator −16 to −20°C or ultra-cryogenic −76 −80°C) thawing (homeothermy 20 25°C refrigeration 2 4°C) on nutritive compositions physicochemical characteristics raw storage period (80 d). Compared with fresh milk, frozen-thawed decreased contents fat, protein, lactose, as well surface tension stability coefficient, whereas increased effective diameter polydispersity index. The average values color (L*, a*, b*) in 4 group samples changed from 83.01 82.25, −1.40 −1.54, 3.51 3.81, respectively, ΔE most did not exceed 2. In contrast other 3 treatments, treated freezing-homeothermic (UFHT) possessed higher fat (5.20 g/100 g), smaller particle (0.32 µm), lowest index value (0.26). confocal laser scanning microscopy images UFHT were similar those illustrating was optimal approach maintain natural quality milk. Our finding provides a theoretical basis for freeze surplus