This study's main highlight to the effect of replacement of milk by different proportions of concentrated whey in the elaboration of ice creams and the characterization of their physicochemical and microstructural properties. Ice creams have high levels of total solids, acidity, and low pH values. All ice creams exhibited Newtonian fluid behaviors while the Power and Casson Law model adequately explained the flow properties. Viscosity and hysteresis area increased as a higher ratio of concentrated whey was added. Ice cream formulations containing a higher proportion of milk showed greater brightness, the ice creams showed a greenish-yellow coloring tendency. The overrun values ranged from 27 to 44%, and ice cream with partial replacement of milk by concentrated whey showed greater resistance to melting. The addition of concentrated whey did not influence the size of the ice crystals, fat globules, and air bubble diameters. However, the higher total solids content influenced the texture of the ice creams, promoting smoother and creamy ice creams. These results highlight the application of concentrated whey on the 50% substitution level, thus being an attractive alternative for the food industry, mainly about the cost-benefit and added value to the product, by enhancing the color, flavor, and texture.

No abstract

Freeze concentration process was used to concentrate milk until the third stage of freeze concentration. Thus, two samples of ice creams were manufacture, one with milk and the other with concentrated milk from the first stage of block freeze concentration, and denominated ice cream 1 and ice cream 2, respectively. Both ice creams were characterized according to physicochemical characteristics, overrun, microscopy, melting rate, texture, color, and rheological properties. The use of concentrated milk influenced the physicochemical properties of ice cream 2, promoting an increase in the total solids, protein, carbohydrates, and ashes content. Moreover, it was noted that ice cream 2 had a higher overrun, lower firmness, smaller ice crystals, and tended to color greenish and yellowish, however had a higher melting rate and larger hysteresis area. The models of the Power Law and Casson satisfactorily described the rheological behavior of ice creams, which proved to be a Newtonian fluid.

Heat treatments are the established food technology for commercial processing of milk. However, degradation of valuable nutrients in milk (as proteins) and its sensory characteristics occur during these processes due to substantial heat exposure. The most important reactions that occur during milk heat treatment are the whey proteins denaturation, its interactions with the casein micelles and aggregation/dissociation of the casein micelles. Microfiltration represents an emerging food processing technology allowing gentle milk preservation at lower temperatures for similar, or better, nutritive value, microbial removal, and shelf stability. Thus, the aim of this work is to review the existing studies on the effects of microfiltration on milk proteins by comparing with the effects of heating treatments.

The skimmed milk was previously concentrated by the block freeze concentration and, thus, used in the manufacture of an ice cream sample with Bifidobacterium BB-12 addition. This sample was compared with two control samples, one ice cream manufactured with skimmed milk, and the other an MRS broth, which supplies an excellent base for comparison of the bacterial survival. All three samples were submitted to the in vitro gastrointestinal assays from the mouth to the large intestine. The initial Bifidobacterium BB-12 viable cell count (> 8 log CFU/g or mL) of both ice cream samples ensured their classification as probiotic products. This behavior was noted during all in vitro steps (from the mouth until the colon). From the mouth to the ileum was observed that both ice creams showed a slight oscillatory probiotic count. For the ice cream manufactured with concentrated milk, it was observed a high bifidobacteria protective effect in the descending colon, with probiotic viable cells count and recovery rate values equal to 9.88 log CFU/g and 112.02%, respectively. Finally, it was possible to conclude that as well as the ice cream with milk, the concentrated milk served as a succesful probiotic carrier.