3.2. Physical Characteristics (Diameter, Thickness, and Spread Factor) of Control and Supplemented Biscuits
The average result of the diameter in the physical characteristics of control and supplemented biscuits is shown in the
Table 3. The maximum mean value (47.25 mm) was recorded in M
S0 whereas the minimum mean value (42.89 mm) was noted in M
S4 (
Table 3). Statistical analysis revealed that the diameter of biscuits had significantly (
p < 0.05) decreased with the gradual increase in alfalfa seed flour supplementation. The decrease in the diameter may be attributed to an increased protein content in the flour blend as reported by [
29]. These results are in accordance with the findings of [
15]. Tiwari et al. [
30] found that the diameter of biscuits decreased with the increase in the dehulled pigeon pea flour inclusion at different levels in wheat flour.
Table 3 shows the average thickness results of control and supplemented biscuits. The maximum mean value (8.10 mm) was observed in M
S4 whereas the minimum mean value (7.53 mm) was found in M
S0 (
Table 3).
Statistical analysis disclosed that the thickness of supplemented biscuits had significantly (
p < 0.05) increased compared to that of control, except M
S1 which contained 5% alfalfa seed flour supplementation. The results achieved are in line with the findings of [
31]. Abu-Salem et al. [
32] found that supplementation of wheat flour with Bambara groundnut flour increased the thickness of the biscuits. Similarly, the average results of the spreading factor in the physical characteristics of control and supplemented biscuits are also mentioned in
Table 3. The maximum mean value (62.76) was noted in M
S0 whereas the minimum mean value (53.12) was noted in M
S4 (
Table 3). Statistical analysis showed that the spread factor of biscuits had significantly (
p < 0.05) decreased with the progressive increase in alfalfa seed flour supplementation. The decrease in the spread factor may be attributed to the effect of the composite flour which forms aggregates with an increased number of hydrophilic sites struggling for the limited free water in the biscuit dough [
15]. Rapid partitioning of free water to hydrophilic sites throughout mixing increased dough viscosity and reduced the spread factor [
33]. The results obtained were in complete agreement with the findings of [
31,
34] found that the spread factor of biscuits decreased with the increase in Bengal gram flour incorporation at different levels to the wheat flour.
3.3. Proximate Composition of Control and Supplemented Biscuits
The average results of the moisture content of control and supplemented biscuits are shown in
Table 4. The maximum mean value (3.57%) was found in M
S0 and the minimum mean value (3.26%) was noted in M
S4 (
Table 4). Statistical analysis disclosed that the moisture content of the supplemented biscuits had significantly (
p < 0.05) decreased compared to that of the control biscuits, except M
S1 which contained 5% alfalfa seed flour supplementation. The moisture content of the flour blend decreased with the addition of alfalfa seed flour, because the moisture content of the alfalfa flour is lower than that of the refined wheat flour. The present results are in agreement with the findings of [
35]. Banureka et al. [
36] found that the moisture content of biscuits increased with the increase in the soybean flour inclusion at different levels in the wheat flour. Similarly, for the crude protein content, the maximum mean value (15.30%) was recorded in M
S4 while the minimum mean value (10.19%) was observed in M
S0 (
Table 4). Statistical analysis revealed that the crude protein content of the biscuits had significantly (
p < 0.05) increased with the gradual increase in the alfalfa seed flour supplementation. The crude protein content increased in the flour blend due to the addition of the alfalfa seed flour, because of the higher crude protein content in the alfalfa seed flour as compared to the refined wheat flour. The present results are in complete agreement with the findings of [
37]. Onoja et al. [
38] reported that biscuits prepared from the blend of fermented legume and wheat flour had a higher protein content compared to biscuits prepared from 100% wheat flour.
For the crude fiber content, the average results of the control and supplemented biscuits are shown in
Table 4. The maximum mean value (1.62%) was observed in M
S4 whereas the minimum mean value (0.73%) was noted in M
S0 (
Table 4). Statistical analysis disclosed that the crude fiber content of biscuits had significantly (
p < 0.05) increased with the progressive increase in alfalfa seed flour supplementation. The crude fiber content in the flour blend increased due to the addition of alfalfa seed flour, because the alfalfa seed flour has a higher crude fiber content than refined wheat flour. Comparable results were achieved by [
39,
40] found that biscuits prepared from the blend of mung bean and wheat flour had a higher crude fiber content compared to biscuits prepared from 100% wheat flour. Therefore, for the crude fat content, the maximum mean value (21.59%) was recorded in M
S4 while the minimum mean value (17.46%) was found in M
S0 (
Table 4). Statistical analysis showed that the crude fat content of biscuits had significantly (
p < 0.05) increased with the gradual increase in the alfalfa seed flour supplementation. The crude fat content of the flour blend is increased with the inclusion of alfalfa seed flour, because the crude fat content of alfalfa seed flour is high compared to refined wheat flour. These results are in accordance with the findings of [
41,
42] found that supplementation with high-oleic sunflower seed and hull-less barley flour increased the crude fat content of whole wheat flour-based biscuits.
Table 4 shows that the maximum mean value of the ash content of the control and supplemented biscuits (1.92%) is noted in M
S4 while the minimum mean value (1.37%) is observed in M
S0. Statistical analysis disclosed that the ash content of biscuits had significantly (
p < 0.05) increased with the progressive increase in alfalfa seed flour supplementation. The increase in ash content could be attributed to the increased inclusion of alfalfa seed in the flour blend. This may be due to the fact that the ash content of alfalfa seed flour is high compared to refined wheat flour. The results obtained are in complete agreement with the findings of [
43,
44] indicated that the ash content of bread increased with the increase in soybean flour at different inclusion levels in the whole wheat flour. Similarly, for the nitrogen free extract, the maximum mean value (66.90%) was found in M
S0 whereas the minimum mean value (56.32%) was noted in M
S4 (
Table 4). Statistical analysis disclosed that the nitrogen free extract of biscuits had significantly (
p < 0.05) increased with the progressive increase in alfalfa seed flour supplementation. The increase in the nitrogen free extract could be due to increased incorporation of alfalfa seed in the flour blend. This may be due to the fact that the nitrogen free extract of alfalfa seed flour is low compared to refined wheat flour. These results were in agreement with the findings of [
37,
45] found that supplementation with soybean flour increased the nitrogen free extract of whole wheat flour–based bread.
3.4. Mineral Contents of Control and Supplemented Biscuits
The mineral content of wheat flour and alfalfa seed flour were checked and are shown in
Table 5. The average maximum mean value of potassium (145.00 mg/100 g) is noted in M
S4 while the minimum mean value (105.30 mg/100 g) is observed in M
S0. Statistical analysis disclosed that the potassium content of biscuits had significantly (
p < 0.05) increased with the increase in alfalfa seed flour supplementation. The increase in potassium content could be due to the increased inclusion of alfalfa seed in the flour blend. This may be due to the fact that the potassium content of alfalfa seed flour is high compared to refined wheat flour. The present results are in complete agreement with the findings of [
39,
40,
41,
42] found that supplementation with high-oleic sunflower seed and hull-less barley flour increased the potassium content of whole wheat flour-based biscuits.
Similarly, the average result of the magnesium content of the control and supplemented biscuits is shown in
Table 5. The maximum mean value (26.64 mg/100 g) was recorded in M
S4 while the minimum mean value (14.65 mg/100 g) was found in M
S0 (
Table 5). Statistical analysis showed that the magnesium content of the biscuits had significantly (
p < 0.05) increased with the gradual increase in alfalfa seed flour supplementation. The increase in the magnesium content could be due to the increased inclusion of alfalfa seed in the flour blend. This may be due to the fact that the magnesium content of alfalfa seed flour is high compared to refined wheat flour. These results are in accordance with the findings of [
38,
39,
40,
41,
42] found that supplementation with high-oleic sunflower seed and hull-less barley flour increased the magnesium content of whole wheat flour-based biscuits.
The maximum mean value of the calcium content (79.60 mg/100 g) was observed in M
S4, while the minimum mean value (43.91 mg/100 g) was noted in M
S0 (
Table 5). Statistical analysis showed that the calcium content of biscuits had significantly (
p < 0.05) increased with the progressive increase in alfalfa seed flour supplementation. The increase in the calcium content could be due to the increased incorporation of alfalfa seed in the flour blend. This may be due to the fact that the calcium content of alfalfa seed flour is high compared to refined wheat flour. Comparable results were achieved by [
15,
46] found that biscuits prepared from the blend of germinated fenugreek seed and wheat flour had a high protein content compared to biscuits prepared from 100% wheat flour.
However, for iron content, the maximum mean value (7.93 mg/100 g) was recorded in M
S4 while the minimum mean value (3.74 mg/100 g) was observed in M
S0 (
Table 5). Statistical analysis revealed that the iron content of biscuits had significantly (
p < 0.05) increased with the gradual increase in alfalfa seed flour supplementation. The increase in iron content could be due to the increased inclusion of alfalfa seed in the flour blend. This may be due to the fact that the iron content of alfalfa seed flour is high compared to refined wheat flour. Similarly, the maximum mean value of the zinc content (1.60 mg/100 g) was found in M
S4 while the minimum mean value (0.94 mg/100 g) was noted in M
S0 (
Table 5). Statistical analysis showed that the zinc content of biscuits had significantly (
p < 0.05) increased with the progressive increase in alfalfa seed flour supplementation. The increase in the zinc content could be due to the increased inclusion of alfalfa seed in the flour blend. This may be due to the fact that the zinc content of alfalfa seed flour is high compared to refined wheat flour. These results are in agreement with the findings of [
43,
44,
45,
46] found that substitution with germinated fenugreek seed flour increased zinc content of wheat flour–based biscuits.
3.5. Sensory Evaluation of Control and Supplemented Biscuits
Figure 1 shows the color of the control and supplemented biscuits. The average results for the color of the control and supplemented biscuits are shown in
Table 6. The maximum mean value (8.00) was observed in M
S0 while the minimum mean value (5.60) was recorded in M
S4. Statistical analysis showed that the supplementation had significantly (
p < 0.05) influenced color of the biscuits. The dark brown color dominated with the gradual increase in alfalfa seed flour. This may be due to the reaction between reducing the sugar and amino acids (Maillard reaction) and caramelization as reported by [
47]. These results are in accordance with the findings of [
32,
45] reported a dark brown color in whole wheat flour-based biscuits supplemented with soybean flour. Similarly, the maximum mean value for taste (8.25) was noted in M
S0 whereas the minimum mean value (5.00) was found in M
S4 (
Table 6). Statistical analysis disclosed that the taste score of biscuits varied significantly (
p < 0.05) between the treatments. Results exhibited a decrease in the quality of alfalfa seed flour–supplemented biscuits in terms of taste. This decrease may be attributed to the beany flavor of alfalfa seed flour. Beany flavor is usually linked with legumes [
48]. In legumes, hydro-peroxides such as aldehydes, ketones and alcohols are produced from linoleic and linolenic acid through enzymatic breakdown by lipoxygnases which may be responsible for the beany flavor [
49,
50]. The present results are in close agreement with the findings of [
34,
46,
47,
48,
49,
50] found that the quality of biscuits in terms of taste decreased with the increase in soybean and rice bran flour supplementation.
The average results for the texture of the control and supplemented biscuits are shown in
Table 6. The maximum mean value (7.85) was recorded in M
S0 whereas the minimum mean value (5.38) was noted in M
S4 (
Table 6). Statistical analysis revealed that the texture score of the biscuits had significantly (
p < 0.05) decreased with the progressive increase in alfalfa seed flour supplementation. This decrease may be due to the increased crude fiber content of alfalfa seed flour in the flour blend. The results obtained are in accordance with the findings of [
31,
32] found that the quality of biscuits in terms of texture decreased with the increased incorporation of bambara groundnut flour.
Therefore, the maximum mean value of the overall acceptability (8.10) was found in M
S0 while the minimum mean value (5.32) was observed in M
S4 (
Table 6). Statistical analysis showed that the overall acceptability quality score of biscuits varied significantly (
p < 0.05) between the treatments. Results revealed a decreased quality of alfalfa seed flour–supplemented biscuits in terms of overall acceptability. Results obtained are in line with the findings of [
30,
32] also reported similar results when they studied dehulled pigeon pea flour–supplemented biscuits. Even though biscuits prepared from composite flour (supplemented biscuits) were of inferior quality in terms of sensory attributes, when assigned for comparison with those prepared from refined wheat flour (control biscuits), the score given by the trained panel of judges remained at fairly good level for all parameters, showing acceptability of the supplemented biscuits.