No description available.

Effective inhibition of starch digestion in vivo may diminish glucose formation and absorption by the small intestine and increase the amount of undigested starch reaching the colon. The enzyme involved in the digestion of starch, alpha-amylase, has been identified and crystallized several years ago. Controversy exists as to whether effective inhibition can decrease starch digestion sufficiently to result in weight loss. The objective of this project is (a) to isolate and characterize alpha-amylase inhibitors from Phaseolus species (b) to synthesize and characterize known inhibitors in an effort to understand their mechanism of action. / The supernatant from ground beans was subjected to reverse phase chromatography. The separated peaks were lyophilized and assayed for alpha-amylase inhibitory activity. The inhibitor with the highest activity (peak 6) was repurified and fully characterized. It was exposed to physiological amounts of endoproteases to check its stability. / A known inhibitor of alpha-amylase was synthesized and studied. Its binding constant has not been previously reported. (Abstract shortened by UMI.)

No description available.

Bipyramidal crystalline, spheroidal crystalline and amorphous proteins were prepared from following four seeds: white kidney, navy (Phaseolus vulgaris) beans; baby lima, large lima (Phaseolus lunatus) beans. A study of the biological properties of the proteins which exhibit the different microstructures, was carried out. The nature of tryptic inhibitory activity and alpha-amylase inhibitory activity were investigated. All protein showed both trypsin inhibitory and alpha-amylase activities; the kinetics of the alpha-amylase revealed non-competitive mechanism. The crystalline isolates showed lower trypsin inhibitory (TI) and alpha-amylase inhibitory (AI) activities than the amorphous isolates. The extents of tryptic hydrolysis (in vitro) were not related to TI indicating involvement of some other factors, in addition to trypsin inhibitory activity. Electropherograms of SDS-PAGE indicated that the major proteins of P. lunatus beans were more resistant to tryptic hydrolysis than the major fractions of the P. vulgaris. Phytate was found to have an effect on trypsin inhibition as well as on alpha-amylase inhibition; in the latter case, however, phytate complexed to protein was required for the inhibitory effect. There were no relationships between tannin content of the proteins and biological activity. Fractionation of bipyramidal crystalline and amorphous proteins by size exclusion chromatography showed that each isolate contained three fractions having approximate MW of 443,000, 200,000 and 150,000 daltons. The 200,000 MW fraction was a principal fraction. The fraction of 150,000 contained most of the trypsin inhibitory activity, alpha-amylase inhibitory activity was not detected in any of the fractions.

This study was directed at elucidating the structural and functional characteristics of legume protein isolates with different microstructures. / Protein isolates with different microstructures (crystalline and amorphous) were prepared from four varieties of Phaseolus beans; white kidney bean and navy bean (P. vulgaris), and large lima and baby lima beans (P. lunatus). The protein isolates were subjected to tryptic hydrolysis at various time intervals, and the effect of hydrolysis on the functional properties of the protein isolates was studied, using bovine casein as control. Reversed phase HPLC with UV detection was used to generate peptide maps of the tryptic hydrolysates, and electrospray mass spectrometry was used to characterize the peptide profile of the protein hydrolysates. / There was no difference between the susceptibility of the crystalline and amorphous protein isolates to tryptic hydrolysis, however, the hydrolytic products of the crystalline isolates showed higher solubility and functional properties compared with those of the amorphous isolates. Limited hydrolysis markedly improved the functional properties of both crystalline and amorphous protein isolates. The effect of hydrolysis on the functionality of the bean protein isolates was higher compared with casein. In general the hydrolysates of the bean protein isolates showed higher functional properties than casein and its hydrolysates. / Reversed phase HPLC peptide mapping of the tryptic digests and ESI/MS of the RP-HPLC fractions showed structural and compositional difference between crystalline and amorphous protein isolates prepared from the same bean variety. The results also showed that off-line ESI/MS, and ESI/MS/MS of RP-HPLC fractions of the tryptic hydrolysates could be used for the structural characterization of the protein isolates.

The fermentation of African locust beans was studied. These beans in the raw state are inedible but may be rendered palatable by fermentation. Both their texture and taste are thereby considerably improved. / The beans were first processed by boiling and dehulling. They were then fermented at 37 (+OR-) 2(DEGREES)C in stationary fermentor units. Physico-chemical, microbiological, biochemical and enzymological investigations were carried out on the substrate undergoing spontaneous fermentation and on radappertized (11 kGy) controls. Reductions in carbohydrate (52%), protein (12%) and energy (9%) contents, as obtained from the mass and energy balances, occurred during fermentation. The physico-chemical changes were due to the action of extracellular carbohydrases and proteases produced by a Bacillus spp. Pure culture inoculation with the Bacillus spp. gave the fermented product within 24 h in contrast to the normal 72 h fermentation period. / Both pH and titratable acidity increased during fermentation. Ammonia was produced as a result of proteolysis. Fermented African locust beans are rich in both protein and fat and feature in the diet of a large proportion of the 200 million people in West Africa.

No description available.

Physical, chemical and sensory attributes were examined on canned green beans (Oregon 1604) of sieve sizes 3 & 4 and 5 & 6 after one and three months of storage at room temperature (RT). The green beans subjected to different pre-blanch conditions in water (T1t1: 160°F - 30 min.; T1t2: 160°F - 90 min.; T2t1: 200°F - 30 min.; T2t2: 200°F - 90 min.) were blanched in a steam exhaust line for 2 min. and 50 sec. at 208-210°F to inactivate the enzymes still active. The control (T3: direct blanch) was significantly different from the others. Heat treatment prior to blanching and the other variables (sieve size and storage) had highly significant effects on all quality attributes of canned green beans. The pH was significantly lowered by pre-blanch and by canned storage. This decrease was considerably faster for sieve 5 & 6 than for sieve 3 & 4. The lowest pH value was obtained for T1t2 and corresponded to the most firm and most green canned green beans. The effects of increasing sieve size, temperature and time of pre-blanch were significant (P ≤ 0.01) on slough. The decrease of sloughing during storage was not found to be significant. The resistance to compression and shear was significantly increased by the lower temperature of pre-blanch (160°F), which activated pectin methylesterase (PME), and also by a longer canned storage time (3 months). Larger green bean sieve size and increasing temperatures, lowered the resistance to compression and shear which was negatively correlated with pH and slough. EDTA-soluble pectins (EDTA-SP) which were significantly higher with lower temperature of pre-blanch and in smaller sieve size were not affected by storage at RT. EDTA-SP, highly positively correlated to resistance to compression and shear, showed a negative relationship with pH and slough. However, water-soluble pectin (WSP) increased with larger sieve size, longer storage and higher temperature, and declined when time of pre-blanch increased. Sensory attributes for texture, appearance, color and flavor had a high degree of correlation with chemical and physical parameters. The judges were more able to distinguish changes introduced by pre-blanch treatments than those related to different stages of storage or different sieve sizes. There was a loss of green color and an increase of yellow and brown color associated with heat treatments. While treatment T1t2 (160°F-90 min.) had the highest retention of green color, the control (T3) displayed the highest loss. Also, firmness and brine clarity of the canned green beans were improved with pre-blanch at the lower temperature (160°F). / Graduation date: 1985

Graduation date: 1955

Graduation date: 1954