Abstract #24

# 24
Predicting quality attributes of yogurt-ice cream through fluorescence spectroscopy.
Niaz Muhammad*1, Amna Sahar1,2, Nuzhat Huma1, Aysha Sameen1, Ubaid Rahman1, 1National Institute of Food Science and Technology (NIFSAT), Faculty of Food, Nutrition and Home Sciences (FFNHS), University of Agriculture Faisalabad (UAF), Faisalabad, Pakistan, 2Department of Food Engineering, Faculty of Agricultural Engineering, UAF, Faisalabad, Pakistan.

Yogurt is a healthy fermented dairy product which possesses various health promoting effects. Transforming yogurt into ice cream tends to increase its shelf life and overall acceptability by the people of all age groups. However, flavor and textural quality of ice cream is of prime importance from customer point of view. Several traditional methods have been used to evaluate the quality of ice cream during the storage. Nevertheless, a rapid prediction method to determine the quality of ice cream at any stage of storage is needed for on-line monitoring. Accordingly, the present study is planned to evaluate the impact of different yogurt concentrations (10–50%) on various compositional and quality attributes of yogurt ice cream [pH, acidity, meltdown properties, over run, SNF (solids-not-fat), total solids (TS), crude protein (CP), crude fat, ash] during storage of 2 mo and to explicate the potential of fluorescence spectroscopy for predicting the changes in these quality attributes of yogurt-ice cream during the storage period. The yogurt-ice cream was analyzed for various parameters; namely, titratable acidity, pH, TS, overrun, melt down, crude fat, CP, and ash %. In parallel, fluorescence spectra were also taken during the intervals at various excitation (250–510 nm) and emission wavelengths (300–620 nm). The findings concluded that the ranges of the selected parameters remained in the acceptable range during the storage of yogurt-ice cream. For instance, pH, meltdown ability, acidity, overrun, CP, SNF, TS, ash, and crude fat values ranged as 5.52–6.56, 7.97–16.10 g/100 g, 0.11–0.73, 30.03–44.50%, 3.48–3.58%, 21.47–23.38%, 31.85–33.22%, 1.10–1.70% and 9.33–11.50% respectively. The regression results revealed that fluorescence spectroscopy has a good prediction potential at various emission and excitation wavelengths (R2 for pH = 0.97, R2 for meltdown = 0.51, R2 for acidity = 0.95, R2 for overrun = 0.97, R2 for CP = 0.99, R2 for TS = 0.98, R2 for SNF = 0.97, R2 for crude fat = 0.98, R2 for pH = 0.11) for determining the quality attributes of yogurt-ice cream during the storage.

Key Words: yogurt, fluorescence spectroscopy, chemometrics