Formulations and processing

We developed three formulations (30-g each) substituting whey protein by isolated soy protein (ISP) at 25% (PB2), 50% (PB3), or 75% (PB1) weight/weight (Table 1), supplemented with soy isoflavones (44.48% w/w) as follow: different amounts of ISP and WPC were homogenised with others dry ingredients in a powder mixer, batter was made by adding dry ingredients to the wet ingredients (liquid and semi-solid), then the batter was shaped into a coated PVC container and placed overnight in freezer at −7 ± 1 °C, each PB was removed from PVC mould, wrapped and stored under refrigeration (10 ± 2 °C). 100 mg of isoflavones were homogeneously mixed in the batter, because concentration has been related with improvement in blood glucose levels between individual diabetics (Jayagopal et al. 2002; Curtis et al. 2012). To correct the isoflavones concentration to 100% we used 2.25 as correction factor.

Ingredients and proportions used in the formulation of 3 protein bars (PB1, PB2, and PB3)

Bold indicates proportion of substitution of whey protein by isolated soy protein in protein bar formulations at 25% (PB2), 50% (PB3), or 75% (PB1)

^aDiluted in 1:50 parts of whey protein concentrate

^b44.48% isoflavones containing 1.23% genistin, 0.14% genistein, 9.55% daidzein, 32.5% daidzein, 0.54% glycitein, and 0.52% glycitein, corrected by a factor of 2.24