In this study wheat flour (WF) was substituted with completed black rice flour (CBRG) and peeled black rice grains (PBRG) with ratio 5, 10, 15 and 20 %. As results, 8 formulas were used to make 8 diets of toast determined the sensory, rheological properties, chemical composition, minerals content were determined. The biological effect on lipid and hematological profile on hypercholesterolemic rats was assayed.
Toast with 15% CBRG was the highest sensory scores in taste, internal colour and over all acceptability scores as (4.41, 4.55 and 4.18), respectively, and was not significantly different (p<0.05) comparing with control toast. The results showed that toast with 20% CBRG contained significantly high content in protein as (11.06). Toast with 20% PBRG had high ash content as (3.22) while, toast with 10% PBRG had high crude fibers content as (5.82).
Farinograph parameter revealed that water absorption of dough decreased to (60.80%) in dough with 10% PBRG. Dough with 10% CBRG was the highest arrival time and development time values as (3.00, 4.00 min), respectively. Dough stability values were found to be high in all toast doughs except for dough with 20% CBRG (12.00 min). Dough with 20% CBRG was the lowest dough weakening value as (10.00 min). Substitution of wheat flour by PBRG induced an increase in resistance to extension to (520 B.U.). Dough with 20% PBRG (85 mm) was the lowest extensibility value (85 mm). The highest proportional number (5.53 P.N.) was found to be in dough with 20% PBRG with being dough with 20% CBRG the lowest energy (47 cm2).
Concerning Protein efficiency ratio (FER), rats fed on toast with 20% CBRG was the highest FER at all rat groups (5.05) and protein intake value was not differing significantly between rats group fed on toast with 15, 10% CBRG, 15% PBRG, 20% CBRG and negative control (-). Greater values of HDL-C were observed in rats fed on 20% CBRG (53.48 mg/dl). Positive control (+) group was the highest TC, TG, LDL-C and VLDL-C as 161.03, 125.17, 109.52 and 25.03 mg/dl, respectively, that's indicated to feeding rats on toast with CBRG and PBRG was significantly (p<0.05) improved lipid parameters as compared with positive control group.
Feeding rats on toast with 20% CBRG introduced the highest Hb value as (14.80 g/dl) as feeding rats on toast with 10% PBRG recorded a marked hematological effect on WBCs count as 4.90 comparing with 3.42 in rats fed on toast with 10% CBRG. This study has demonstrated that addition of completed black rice grains CBRG and peeled black rice grains PBRG were considered as a good functional ingredient for adding value of food product, more important, may contribute to health benefits where lipid and hematological parameters were significantly (p<0.05) improved in rats fed on toast with ratios of CBRG and PBRG.