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الكلمات المفتاحية: بديل اللبن، حليب الترمس، المؤشرات الكيميائية، القبول العام، الحموضة

Chemical and sensory properties of yoghurt substitute prepared by adding different proportions of lupin milk to cow's milk

Abstract

This research was carried out in the laboratories of the Department of Food Science, Faculty of Agricultural Engineering - University of Damascus with the aim of manufacturing a milk alternative by adding different ratios of lupin milk to cow's milk and studying some chemical, microbial, and sensory properties of the manufactured milk alternative. The ratio of (1:5) (water: lupin) was chosen for the production of lupin milk. The composition of the lupin milk at this ratio was similar to the composition of cow's milk used in these experiments, where the amount of dry matter was (11.68%). Then, a milk substitute was manufactured by replacing part of the cow's milk with increasing ratios of lupin milk (50:50 - 75:25 - 100:0 - 25:75 - 0:100). It was noted during the analysis that the protein percentage increased with the rise in lupin milk ratio, where it was (3.35 - 3.18 - 4.26 - 5.20 - 4.72) when using the ratios (25 - 0 - 75 - 50 - 100) in order. The plant-based milk substitute is also characterized by a high fiber content, with increasing percentages as previously mentioned in order of (0.15 – 0 – 0.38 – 0.62 – 0.82). In contrast, a decrease in fat content was observed with an increase in the replacement ratio. The substitution of cow's milk with lupin milk significantly affected the Titratable acidity values of the milk substitute, with the Titratable acidity reaching (0.96) in the control sample (100:00) and decreasing to (0.51) in the milk substitute sample (00:100). During storage, the acidity was significantly affected, increasing in all samples on the seventh day and then significantly decreasing on the fourteenth day. When estimating the counts of yeasts and molds, an increase in the yeast ratio was observed with an increase in the substitution percentage and the preservation percentage. When estimating the count of lactic acid bacteria, a decrease in the percentage of Streptococcus thermophilus was noted with an increase in the ratio of lupin milk, where the counts were (8.55 – 8.00 – 7.60 – 7.15 – 6.81) CFU/ml log10 when using the ratios (0 – 25 – 75 – 50 – 100) respectively. It was also observed that the percentage of Lactobacillus delbrueckii subspecies bulgaricus decreased with the increase in the replacement percentage, which was (7.85 – 7.65 – 7.35 – 6.65 - 6.95) CFU/ml log10. As for coliform, it was noted that all samples were free from coliform bacteria. During the sensory evaluation, it was observed that the samples with a substitution ratio of (25:75) and (50:50) (cow's milk: lupin milk) were the best in terms of sensory acceptance compared to the samples with a substitution ratio of (75:25) and (100:00), where the acceptance rate decreased as the substitution ratio increased, and sensory     acceptance declined in all samples over time.

Keywords: Milk substitute , lupin milk, chemical indicators , general acceptance, acididty