Emprego de ultrassom na fabricação de leite em pó com adição de probióticos

Abstract

Milk and derivatives are food of great consumption in the world, and thus move much of the processing industries in search of technological innovations, aiming at improvements in the quality of the products and efficiency in their productive processes. The objective of this study was to evaluate the effects of ultrasound at 25 kHz frequency in different amplitudes and modes of operation (sweep and normal) in concentrated whole milk through acidity, viscosity, pH, insolubility and brightness to later define the best way to treat the milk to submit it to the spray dryer process. Once the best condition was established, the concentrated milk was subjected to the spray dryer, with or without probiotics Lactobacillus rhamnosus. The manufactured milk powder was stored at 25, 35 and 45°C and evaluated for 120 days in relation to water, moisture and color activity. Reconstituted milk was evaluated for acidity, pH, insolubility, composition (fat, protein, casein and lactose), encapsulation efficiency and lactic acid bacterial counts.The US applied in concentrated milk, in the normal mode of operation, showed a decrease in the values of acidity and viscosity. In the milk powder resulted in improvements in the homogenization and growth of lactic bacteria. The US promoted acceleration of the darkening of the samples stored at 45°C. Aw and humidity increased in all treatments during the storage period, more expressively at 45°C, where high values of insolubility, decrease of the values of luminosity and pH were observed. Reconstituted milk submitted to the US showed lower protein, casein and lactose levels than untreated reconstituted milk. With the packaging used (consisting of a layer of low density polyethylene, one layer of adhesive and one layer of metallized polyester, outer layer) of 75 microns thickness the shelf life estimate at 25°C, 35°C and 45°C was 127, 55 and 17 days for AB treatment; for the US and probiotic samples was 145, 53 and 15 days and for the samples without US and with probiotics was 150, 54 and 21 days. It is suggested to conduct new research with new types of packaging and US parameters, in addition to different parameters of powdered milk quality and use of recommended values as probiotic therapeutics in reconstituted milk.