ABSTRACT
Raw and processed (soaked, soaked/boiled, roasted) wattle, Acacia saligna subspecies (subsp.) saligna, pruinescens, stolonifera and lindleyi, seeds were analysed for nutritional and antinutritional qualities. Whole wattle seeds mainly comprised proteins (27.6-32.6%) and carbohydrates (30.2-36.4%), which had approximately 12.0-14.0% fat and 13.0-15.0% crude fibre. Palmitic (9.6%), stearic (2.0%), oleic (20.0%) and linoleic (64.3%) acids were identified by gas chromatography (GC) analysis. Phenolic (â¼0.2%), oxalate (2.2-3.4%) and saponin (2.6-3.0%) contents were fairly high; phytate content was low. All untreated samples contained a high level of trypsin inhibitor (2474.3-3271.4 trypsin inhibitor units per gramme (TIU/g) of flour) and low level of α-chymotrypsin inhibitor (120.4-150.6 CIU/g). Soaking overnight following with 2-min boiling led to a significant reduction of protease inhibitor activity. Roasting at 2 min or longer was sufficient to reduce both trypsin and α-chymotrypsin inhibitors to negligible values, also to reduce phytate, oxalate and saponin contents, simultaneously enhanced the nutritional values of wattle seeds.
Subject(s)
Acacia/chemistry , Carbohydrates/analysis , Cooking , Enzyme Inhibitors/analysis , Fatty Acids/analysis , Nutritive Value , Plant Proteins/analysis , Seeds/chemistryABSTRACT
The effect of roasting on the phenolic components of Australian wattle (Acacia victoriae Bentham) seed was investigated. Wattle seeds were roasted at 200°C for 5-30min and ground to flour, which were then extracted with 70% acetone. The total phenolic and flavonoid contents of the extracts were determined, and the phenolic components were analysed by reverse phase-high performance liquid chromatography (RP-HPLC) coupled with an on-line post-column reaction system to determine the active antioxidant peaks. The major peaks were then purified by preparative HPLC and identified by gas chromatography-mass spectrometry (GC-MS) analysis. Roasting of wattle seeds resulted in significant increases in its soluble phenolic content. The concentration of total phenolics and flavonoids in the seeds roasted for 30min was more than nine and four times higher, respectively, than that in the raw seeds. The major phenolic acids present in wattle seeds were found to be succinic and gallic acids, the concentration of which increased by up to 10-fold as a result of roasting.
ABSTRACT
An Acacia victoriae trypsin inhibitor (AvTI) was purified from the seeds of prickly wattle (A. victoriae Bentham) by salt precipitation, ion-exchange and gel filtration chromatography, and its degree of glycosylation, amino acid composition, and kinetic properties were determined. Gel electrophoresis revealed at least four glycoprotein bands in the crude extract, salt-precipitated and ion-exchange protein fractions, while the purified AvTI showed only one band and a degree of glycosylation of 2.06%. Glutamate (13.3%), aspartate (10.3%), leucine (7.62%) and lysine (7.01%) were the major amino acids in AvTI while the contents of sulphur-containing amino acids, cysteine (1.38%) and methionine (0.75%), as well as of tryptophan (1.17%) were low. Its dissociation constant (Ki) for the inhibition of bovine trypsin was found to be 1.06×10(-8)M, indicating a high affinity between AvTI and this enzyme, and its role as a competitive inhibitor was confirmed by a double reciprocal plot. These results complement our earlier studies which indicated the presence of three isoforms of this Kunitz-type trypsin inhibitor in prickly wattle seed.
ABSTRACT
Extracts from either ground whole wattle seeds or uncoated cotyledons were obtained using water, alkali, or ethanol. These extracts were then analyzed for their protein molecular weight and electrophoretic profiles using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and capillary electrophoresis, respectively. Water extracts and those from the cotyledons gave higher material yield and contained significantly more proteins than other extracts. Furthermore, the proteins ranged in molecular weight from 6 to 92 kDa, with the highest concentration between 27 and 61 kDa. Water extracts, even at very low protein concentrations (0.17-1.12%), formed stable emulsions, containing up to 50% canola oil, and these emulsions were affected by pH (4-9), ionic strength (0.25-1% NaCl), and retorting (115 degrees C for 30 min). The study showed that water-soluble wattle extracts have great potential as emulsifiers and stabilizers for the food industry, especially at low pH levels.
