Nutritional composition, antinutritional factors, bioactive compounds and antioxidant activity of guava seeds (Psidium Myrtaceae) as affected by roasting processes

The purpose of this study was to explore the influences of roasting process on the nutritional composition and nutritive value, antinutritional factors, bioactive compounds and antioxidant activity of guava seeds. Roasting process caused significant (P <= 0.05) decreases in moisture content, crude protein, crude fiber, ash and mineral contents, isoleucine, arginine, glutamic and total aromatic and sulfur amino acids, antinutritional factors (tannins and phytic acid) and flavonoids, while oil content increased. Subjecting guava seeds to 150 degrees C for 10, 15 and 20 min increased the total essential amino acids from 35.19 g/100 g protein in the raw sample to 36.96, 37.30 and 37.47 g/100 g protein in roasted samples, respectively. Protein efficiency ratio (PER) of guava seeds roasted at 150 degrees C for 10, 15 and 20 min were about 1.08, 1.14 and 1.18 times as high as that in unroasted seeds. Lysine was the first limiting amino acid, while leucine was the second limiting amino acid in raw and roasted guava seeds. Total phenolic contents was significantly (P <= 0.05) increased by roasting at 150 degrees C for 10 min. However, roasting at 150 degrees C for 15 and 20 min caused significant decrease in the phenolic content of guava seeds. Guava seeds subjected to roasting process showed higher DPPH radical scavenging and reducing power activities.