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The aim of this study was to evaluate the influence of the growth of lipolytic bacteria in raw goat milk stored under refrigeration for different periods on quality parameters of goat milk powder during its shelf life. Fresh goat milk (100L) was collected after milking, divided into 3 identical fractions, and stored at 4°C for 1, 3, and 5d. On d 1, 3, and 5, one sample (1L) was collected and used for microbiological and chemical analysis, and the remaining fraction (almost 30L) was spray dried and stored at 25°C. Milk powder was submitted to microbiological, chemical, and sensory analysis immediately after production, and on d 60, 120, and 180. Lipolytic psychrotrophic counts and total free fatty acid content did not increase in raw milk during storage. However, peroxide value, caprylic and capric acid concentrations, and total free fatty acid content of milk powder increased during 180d of storage, with higher levels found in milk powder manufactured with raw milk stored for 5d. Capric odor and rancid flavors increased in milk powder during storage, regardless the of storage of raw milk for 1, 3, or 5d. Heat treatments used during powder processing destroyed lipolytic psychrotrophic bacteria, but did not prevent lipolysis in milk powder. Results of this trial indicate that the storage of raw goat milk at 4°C should not exceed 3d to preserve the quality of goat milk powder during its shelf life of 180d.

In this study, physical characteristics of goat milk powder produced with the addition of soy lecithin at levels of 0 (control), 0.4, 0.8 and 1.0 g lecithin ⁄ 100 g of total solids in concentrated milk before the spray drying process were investigated. Goat milk was pasteurised, concentrated at 40% of total solids, spray dried and packed in plastic bags under vaccum conditions. Lecithin addition decreased the wetting time of milk powders, although no influence was observed on dispersibility, water sorption, water activity and particle size distribution of the powders. Powders with higher levels of lecithin showed significantly lower brightness, with a greater intensity of yellow colour. It was concluded that lecithin addition before spray drying process at the minimal proportion in concentrated milk of 0.4 g lecithin ⁄ 100 g of total solids in concentrated milk is useful for achieving more rapid wetting time of goat milk powder.

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