Improving Characteristics of Frozen Yogurt Enriched with Loquat Leaves Extract

Document Type : Original Research

Authors

Food Science and Technology Dept., Faculty of Home Economic, Al-Azhar University, Tanta, Egypt.

Abstract

Frozen yogurt is a fermented frozen dairy dessert that combines the physical qualities of ice cream with the sensory and nutritional benefits of fermented milk. Frozen yogurt is considered a healthier alternative to ice cream because of its low-fat content. In this study, the frozen yogurt was incorporated with 1% loquat leaf extracts obtained using 30, 70, and 90% ethanol. The final product was evaluated for physical characteristics (pH, total acidity, melting rate and, color), total phenolic content, microbiological analysis, and sensory evaluation. The results obtained illustrated that leaves extract obtained using 90% ethanol has the highest content of flavonoids (1.023 mg QE/g). Pyrogallol was found to be the main phenolic compound in the 70% ethanol extract. All supplemented frozen yogurt samples were effective against all tested microbial strains with 1% loquat extracts. The lowest MIC (minimum inhibitory concentration) values observed with the samples contained 1% of 30% ethanolic loquat leaf extract at concentration of 5.0 μg/μl for Staphylococcus aureus and Escherichia coli. Data also indicated that the control sample recorded the highest pH value (4.67) and was the fastest in melting rate. Furthermore, the a* values of frozen yogurt with 90% ethanol extract were lower, while the b * values were higher. The same samples had a significantly higher amount of total phenolic content by 3.04 times compared to the control sample. The control frozen yogurt registered the highest value of the total plate count (30x102cfu/g).

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