[Effects of milk solids-non-fat content on physical, chemical and sensory properties of frozen yogurt]

ABSTRACT

Frozen yogurt is obtained by freezing a mixture containing milk fat, milk solids-non-fat [MSNF], sweeteners, stabilizers, and yogurt. Increased milk solids-non-fat is one way to avoid undesirable changes in texture observed in low-fat products. This increase in MSNF also helps greatly improve health properties of these products. Since frozen yogurt is considered a low-fat dessert, in this study the effects of milk solids-non-fat content on its physical, chemical and sensory characteristics were investigated. Ingredients included milk [2.5% fat and 8% solids-non-fat], skim milk powder [98% solids-non-fat], cream [30% fat], starter yogurt [DVS Lat 1/63, including Streptococcus salivarius subsp. thermophilus and Lactobacillus delbrueckii subsp.bulgaricus], sugar, vanilla powder, and panisol ex. All samples contained 8% fat, 13% sugar, 0.3% stabilizer and 0.09% vanilla. To produce test samples,the milk solids-non-fat content was adjusted at 13%, 16% and 19% levels with skim milk powder. Statistical analysis of the data was performed by completely randomized two-factor design with 3 replications using the MSTAT-C software, and analysis of variance was done with Duncan's multiple range test [p<0.05]. For drawing diagrams the Excel software was used. Titratableacidity, pH, viscosity, overrun capacity and melting characteristics of ice cream were influenced favourably significantly [p<0.05] by increasing MSNF. Increasing the MSNF content significantly [p<0.05] decreased pH, overrun capacity and resistanec to melting of ice cream, while it increased titratable acidity and viscosity. The dataalso showed that samples with 13% MSNF resulted the highest scores in texture and total acceptance [p<0.05]. Increases in milk solids-non-fat content of frozen yogury affects favourably its properties. Based on the findings in this study, 13% MSNF is suggested for producing concentrated frozen yogurt