الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 113 |  |  |
| | | from | 113 | | |
Abstract
I- Chemical analysis
The chemical composition of dry seeds of 10 kidney bean genotypes are determined and data indicate that studied genotypes are rich and inexpensive sources of dietary fibers (6.12%), minerals (4.09% TAC). The highest level of crude protein (34.45%) was recorded in seeds of Poulista followed by Olathe (32.96%) then Monica (31.36%) but lower levels in the seeds of Bronco and Julia and the lowest level (27.27%) were observed in seed of Mexico.
Total soluble and reducing sugars:
The content of total soluble sugars (TSS) and total reducing sugars TRS were determined quantitatively and calculating the TNRS by difference. The level of TSS extracted from dry seeds was highest value in extracts obtained from seeds of Duel (3190 μg/ml) and lowest one was recorded in Tema seeds (1177 μg/ml). The levels of total non-reducing sugars (TNRS) are lower when compared with TSS but higher than the levels of TRS.
Nitrite and nitrate contents:-
The nitrite and nitrate contents in dry seeds of kidney bean genotypes studied here are showed that the highest level of nitrite in seeds of Bronco (7.01 mg/kg dwb) followed by C.S.W. (5.11 mg/kg) and lowest one was recorded in Olathe (2.38 mg/kg). The most important result recorded here that the nitrite level was under the toxic level (10 mg/kg) in food stuffs. The nitrate levels in seeds of Poulista, C.S.W. and Monica were 146, 141 and 140 mg/kg dwb respectively but lower levels were recorded in Mexico (120 mg/kg).
Vitamin C content:-
Vitamin C or L-ascorbic acid content is low when compared with tomatoes or potatoes and the highest level (3.24 mg/kg defatted meal) was recorded in the seed of Olathe but the lowest one determined in seeds of C.S.W.
Antinutritional Factors (ANFs)
Total trypsin inhibitors (TTI) and non-protein trypsin inhibitors (NPTI)
Total trypsin inhibitors (TTI) and non-protein trypsin inhibitors (NPTI) were assayed in the seeds of all genotypes and the results indicate that the levels of TTI were higher than NPTI. The highest level of TTI (40.96 mg/g defatted meal) was recorded in the seeds of Monica followed by Poulista and lowest one was in seeds of Duel (8.04 mg/g defatted meal). The same trend was also observed in the respect of NPTI levels i.e. the samples having higher values of TTI also having higher levels of NPTI. Our results also showed the white-coat seeds contain higher levels of TTI and NPTI than those have colored-coat seeds.
-Amylase inhibitors (AI):
-AIs activities were extracted from the seeds of genotype samples and the inhibitory activity was examined against Porcine pancreatic -amylase (PPA). The lowest level of -AIA was found in kidney bean Poulista genotype (100 u/g) which contained about one fifth of that present in black kidney bean genotype Julia (498).
In addition to, our results also indicate the black-coat seeds (Duel and Julia) contain higher levels of -AIs than those determined in white-coat seeds (Poulista and Bronco). In contrary, it is noted the white-coat seeds of C.S.W. contain high content of -AIs (452 u/g).
Data indicated that the acidic extractant (0.1 M HCl) is more efficient than distilled water in extraction of -AIs from the all studied samples whereas the higher levels were always recorded when HCl was used as extraction solution.
Phytic acid
The concentration of phytic acid in all studied genotypes was determined in defatted meal and the results indicate that lowest level of phytic acid was recorded in seeds of Duel (Black seed-coat) to be 1.96 mg/g) and the highest one (5.55 mg/g) found in the seeds of C.S.W. (white seed-coat).
Enzymatic activities in soaked samples
(a) Protease activities:-
The proteolytic activities of kidney bean samples were determined in crude homogentes and expressed as Amino Acid Released in 60 min (AAR) the results showed that the lowest level of protease was recorded in the sample of seed of Mexico (4.5 g /60 min) but the highest one was found in seeds of Yellow (41.7 g /60 min). Our results also indicate that there are no correlation between the genotypes with colored seed coats and other genotypes.
(b) Peroxidase activities (POD):-
Results of POD activities in kidney bean shown indicated that the highest enzyme activity was recorded in soaked seeds of Julia followed by Bronco. The lowest level of POD was found to be 3.5 unit /g in Duel seed genotype.
(c) Phenylalanine ammonia lyase (PAL):-
PAL activities assayed in different kidney bean genotype samples were determined using phenylalanine as enzyme substrate and extracts obtaining from soaked seeds. Our results showed that the highest level (13.5 unit/100 g) was recorded in seed of Tema and followed by Monica (11 unit/100 g) and Julia but lower levels were detected in black seed-coat genotypes (Duel). Low PAL activities due to lowering of enzymatic browning and improvement of quality parameters and sensory of soaked product. On the other hand, the increase of PAL activities in kidney bean tissues led to accumulation of phenolic acid namely cis-cinamic acid which play an important role in resistance process against pathogens and insects.
(d) Polyphenol oxidase (PPO):-
The activities of PPO indicate that there are obvious variations among black, colored and white genotypes. Whereas, black seed-coat genotypes contain higher levels of PPO than those reported for white seed coat and lower levels in colored ones. The highest level of PPO (160 unit/100 g) is recorded in the seeds of Duel followed by Julia (158 unit/100 g) and the lowest one found in seeds of Olathe (102 unit/100g). Our results also indicate that there is no difference between the two black genotypes Duel and Julia (160 and 158 unit/100 g).
(e) Tyrosinase activity-
Tyrosinase activities were measured in the presence of tyrosine as substrate, the highest activity level (7.4 unit/100 g) was recorded when the enzyme extract obtained from seeds of Tema followed by Julia and then Bronco. Data are also showed that the enzyme activity in extracts from black seed-coat genotypes Duel was the lowest level of the tested enzyme on the other hand Julia seeds was higher by about 137% than Duel.
Polyphenolic compounds content:
The concentrations of polyphenolic compounds in whole seeds of studied genotypes were spectrophotometerically assayed and the results showed that total phenolic compounds (TPCs) always higher than phenolic acids (PAs) and the last are much higher than total flavonoids. Our results also indicate that white seed-coat genotypes (WSC) contain lower levels than those determined in black seed coat (BSC) and brown seed coat (Brown SC). These results indicated that the levels of TPCs in ten legume samples varied considerably from 0.15 to 2.2 mg of the whole seeds of C.S.W. and Olathe respectively and correlated visually with seed-coat color; i.e. seeds with darker seed-coats gave higher polyphenols contents.
Correlation between polyphenols levels and seed coat colors:
Data illustrated that phenolic compounds appeared to be concentrated in seed coats especially in legume sample with darker seed coat (genotype Olathe, duel and Mexico).
Total flavonoid content:
Total flavonoids content were assayed and the results showed that the two brown seed-coat genotypes Olathe and Mexico have the highest levels of flavonoids followed by red seed-coat (Tema). On the other hand, the four white seed-coat genotypes recorded lower levels and same trend was also observed with black seed-coat genotypes (Duel and Julia).
Antioxidant activity of total phenolic compounds extracted from dry bean
Antioxidative activities of crude extracts from whole seeds of ten kidney bean genotypes, cotyledons and seed-coats (testa) used in this work were measured by ferric thiocyanate (FTC) method which measure the amount of peroxide formed during the initial stage of linoleic acid oxidation. The individual activity of testa extracts showed low absorbance values at 500 nm which indicated marked inhibition of oxidation of linoleic acid by all extracts. All of them were more effective than -tocopherol, a common natural antioxidant.
The extracts of whole seeds showed lower antioxidant activities than those recorded for testa extracts and this are consistent with the levels of phenolic compounds in these extracts. It could be concluded that the higher the phenolic content is the stronger the antioxidative activity of the
The antioxidative activities of various extracts which indicated that testa extracts were more effective in retarding the oxidation of linolic acid after more than 30 days of incubation than the corresponding extracts of whole seeds. In general all the kidney bean extracts exhibited excellent antioxidative activities with about 90% or more inhibition of linoleic acid oxidation by the end of incubation period but much lower inhibitory effects were observed by most of the whole seeds extracts.
Fractionation of TPCs by high-performance liquid chromatography (HPLC )
Results of TPCs fractionation using a HPLC procedure for separating and quantifying phenolic acids in dry beans (Phaseolus vulgaris L.). Ferulic acid, p-coumaric acid, sinapic acid, and caffeic acid were detected and quantified in all genotypes. The average phenolic acid content of dry bean sample was determined to be 31.2 mg/100 g. Total phenolic acid content among all genotypes varied between 0.201 to 2.187 mg/100 g of bean samples. Ferulic acid was the most abundant phenolic acid present in all samples, whereas intermediate levels of p-coumaric acid and sinapic acid were extracted from all bean samples.