Effect of boiling and roasting on the proximate properties of asparagus bean (Vigna Sesquipedalis)
The proximate properties of asparagus bean flour obtained after boiling and roasting at 100 and 160°C, respectively for varied period were evaluated and compared in this study. Results showed that boiling for 40 min significantly (p<0.05) reduced protein and moisture contents by 10 and 6% respectively, but increased carbohydrate (CHO) content by 8%. Furthermore, it insignificantly (p>0.05) reduced fat, fibre and ash contents by 28, 13 and 21%, respectively. On the other hand, roasting for 20 min significantly (p<0.05) reduced protein and moisture by 11 and 43%, respectively, but increased CHO content by 14%. However, roasting reduced fat, fibre and ash by 20, 18 and 10%, respectively. However, the observed reduction was statistically insignificant (p>0.05). Overall, the effects observed in this study were time dependent, suggesting possible enhancement with increasing processing time. Roasting markedly decreased the moisture content, implying that 20 min roasting probably enhanced the stability and kept the quality of the asparagus bean flour. Thus, roasting may be preferred to boiling for commercial production and storage of asparagus bean flour.
Key words: Asparagus bean, boiling, roasting, crude protein, ash, fibre, moisture, fat, carbohydrate.