Md Rahmatuzzaman Rana
Department of Food Engineering and Tea Technology, Shahjalal University of Science and Technology, Sylhet, 3100, Bangladesh
Majharulislam Babor
Department of Food Engineering and Tea Technology, Shahjalal University of Science and Technology, Sylhet, 3100, Bangladesh
Ashfak Ahmed Sabuz
Postharvest Technology Division, Bangladesh Agricultural Research Institute, Gazipur, Bangladesh
Soy yogurt, Sweeteners, Discrimination analysis, Acceptability
Food Safety and Security
Nutrition, Yogurt
Materials: Soybean (Glycine max) of BARI-5 variety was obtained from Bangladesh Agricultural Research Institute (BARI), Bangladesh, and stored at 4 ?C until use. Sucrose, honey, artificial sugar (sucralose), and strawberry flavor were obtained from the local market. All chemicals were of analytical grade. Commercial fresh yogurt was used for the isolation of the starter culture, which contained Streptococcus saliferous subsp. thermophilus (108 CFU/mL) and Lactobacillus delbrueckii (108 CFU/mL). Preparation of soymilk: The soymilk was prepared following the method described by Mei et al. [30] with slight modification. Briefly, 500 g of dry, mature, whole soybeans were soaked in 0.3% NaHCO3 (1:3 w/v) at 25 ?C for 12 h. After proper decantation, the seeds were dehulled manually and then blended with distilled water (1:8 w/v) for 5 min. The slurry was sieved through a double-layer cheesecloth. The supernatant portion was collected and simmered for 10 min, followed by cooling and storing at 4 ?C until use. Preparation of soy yogurt: Into the freshly prepared soymilk, any of the sweeteners and the flavor were added according to the formulations indicated. Subsequently, the mixture was pasteurized in a water bath at 85 ?C for 30 min and then cooled to 42 ?C. Afterward, the mixture was inoculated with 4% (w/v) yogurt starter culture, with a minimum count of approximately 7 log CFU/mL. The inoculated samples were incubated at 42?C for 7 h. After processing, the soy yogurts were subjected to physicochemical and sensory analysis. Physicochemical characteristics: The proximate composition of soy yogurt samples was determined using the standard methods. Moisture, protein, ash, and fat contents were determined using the gravimetric method (AOAC method 934.01), micro-Kjeldahl method (AOAC method 991.20), (AOAC method 923.03), and Gerber method, respectively. The acidity was determined by the samples titrating against 0.1 M sodium hydroxide and was expressed as % lactic acid. The pH of soybean, soymilk and soy yogurt was measured using a calibrated pH meter (Hanna 201A, Germany). TSS were determined using a hand refractometer (Master-53S, Atago, Japan) and expressed as ?Brix. The specific gravity of soy yogurt was estimated at room temperature using a standard specific-gravity bottle of 50 mL capacity. Sensory analysis: Analysis of the sensory characteristics was conducted by 25 semi-trained panelists in isolated cabins with the same lighting and temperature conditions. The evaluation was performed on a nine-point Hedonic scale, in which 1 corresponded to ‘dislike extremely’ and 9 corresponded to ‘like extremely’. The panelists evaluated the soy yogurt samples for the attributes of color, flavor, taste, texture, and overall acceptability. Statistical and chemometric procedures for data analysis: In all assays, final result values were calculated by averaging the results for nine different batches of soy yogurt samples and were expressed as mean and standard deviation. In the chemometric analysis, a subset of chemical parameters, i.e., moisture, protein, fat, and lactic acid, were considered. In the data analysis, Linear discriminant analysis (LDA) was implemented using Python 3.7 to trace and predict the sweeteners in the soy yogurt samples.
Journal of Agriculture and Food Research 5 (2021) 100155
Journal