Effect of Substituting Purple Rice Flour for Wheat Flour on Physicochemical Characteristics, In Vitro Digestibility, and Sensory Evaluation of Biscuits

Table 2

Basic characteristics of the biscuits containing different levels of purple rice flours^∗.

Nutritional properties	Control wheat biscuit	Purple rice flour substitution (%)
		25	50	75	100
Moisture content (%)	3.57 ± 0.06^e	4.60 ± 0.12^d	5.64 ± 0.08^c	6.33 ± 0.14^b	7.36 ± 0.13^a
Crude protein (%)	7.35 ± 0.04^a	6.62 ± 0.03^b	6.61 ± 0.02^b	6.13 ± 0.04^c	5.82 ± 0.01^d
Protein digestibility (%)	41.13 ± 0.53^e	60.15 ± 0.29^d	65.36 ± 0.26^c	74.05 ± 0.04^b	79.65 ± 1.01^a
Total dietary fiber (%)	2.01 ± 0.09^d	3.06 ± 0.10^c	3.26 ± 0.04^c	4.40 ± 0.05^b	5.53 ± 0.02^a
Total fat (%)	28.43 ± 0.14^NS	28.59 ± 0.07	28.36 ± 0.20	28.69 ± 0.62	29.22 ± 0.46
Ash (%)	1.69 ± 0.02^d	1.86 ± 0.01^c	2.16 ± 0.02^b	2.26 ± 0.01^a	2.32 ± 0.04^a
Total carbohydrate (%)	59.22 ± 0.14^a	58.83 ± 0.12^ab	57.86 ± 0.29^b	56.11 ± 0.54^c	54.38 ± 0.47^d
Total starch (%)	33.91 ± 0.15^a	32.35 ± 0.11^b	31.62 ± 0.34^bc	30.89 ± 0.19^c	30.36 ± 0.83^c
AUC^† of digested starch (mg min·dL^−1)	668.69 ± 0.95^a	607.66 ± 0.56^b	559.38 ± 0.43^c	487.23 ± 1.32^d	423.25 ± 1.43^e
pGI^‡	72.78 ± 0.05^a	69.76 ± 0.03^b	67.38 ± 0.02^c	63.81 ± 0.07^d	60.64 ± 0.07^e

^∗Values represent mean ± standard error; in each row, sample means not having the same letter attached to them are significantly different (Duncan’s multiple range test, ); NS = not significant difference. ^†Area under the curve (AUC) of digested starch can predict glycemic response of each biscuit. ^‡Predicted glycemic index.