EFFECT OF DIFFERENT POSTHARVEST TREATMENTS ON ANTINUTRITIONAL FACTORS IN SOME COMMONLY CONSUMED LEAFY VEGETABLES IN CAMEROON

Effect of squeeze-washing, boiling in kanwa (a local alkaline salt) and drying of the leaves of some leafy vegetables ( Vernonia colorata, V. calvoana var. bitter, V. calvoana var. nonbitter and V. amygdalina ) consumed in Cameroon on antinutritional factors were evaluated. Results show that values for polyphenols were high in the unprocessed leaves. These values were reduced by 84.5% in V. amygdalina during processing. Sun drying and oven drying at 75C also caused slight losses ( P <  0.05) in polyphenols. Saponin values were high in these four species but were considerably reduced by processing, rendering the nutrients in these leafy vegetables more bioavailable. Reductions ( P <  0.05) were also observed for proteins as a consequence of processing by squeeze-washing and use of kanwa. Similar trends were found for oxalic acids. Losses of up to 73% oxalic acids were observed in samples after processing. With the exception of drying, significant losses in minerals were observed due to these processes. This study, therefore, suggests the use of some of these different processing techniques to reduce the levels of antinutritional factors in these leafy vegetables.

PRACTICAL APPLICATIONS

The different species of leafy vegetables ( Vernonia ) are potentially rich sources of provitamin A, vitamin C and minerals. Use of appropriate processing and preservation technology makes these vegetables available at off seasons and in cities of high demand and improves on the actual nutritional value to the consumers. Industrially, these vegetables can be processed by squeeze-washing and the use of minimal quantities of kanwa and possibly dried at 45C for use in urban centers.     

ANTIOXIDANT POTENTIAL OF 5-n-PENTADECYLRESORCINOL

The antioxidant potential of 5-n-pentadecylresorcinol was determined with five different oils. Alkylresordnol (AR) was added at 0.025%, 0.050% and 0.075%, respectively. For comparison, 0.01% butylated hydroxyanisole (BHA) was used as antioxidant. Oils were incubated at 10, 25 and 40C. Peroxide values were determined at different time intervals. Accelerated tests using a pro-oxidant were also conducted with each oil. AR was shown to slow oxidative rancidity of the oils.
The ability of AR to slow lipid oxidation in cereal products was also studied. Wheat bran, rye bran and whole grain millet meal were treated with 0.050% and 0.075% AR and BHA, respectively, and stored at 40C. Peroxide values were determined at different time intervals. AR was shown to slow lipid oxidation in cereal products.     

HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC DETERMINATION OF ANTIOXIDANT LIGNAN GLYCOSIDES IN SOME VARIETIES OF SESAME

The difference in the distribution of sesamin, sesamolin, sesaminol glucosides and sesamolinol components in representative varieties of sesame were compared. Quantitation was achieved by HPLC determination using an external standard. The most abundant lignan glucosides in sesame seed were sesaminol triglucoside. The content of sesaminol triglucoside in 100 g seeds ranged from 14.1 to 91.3 mg with an average value of 68.4 mg; that of sesaminol diglucoside from 8.2 to 18.3 mg with an average value of 11.6 mg; and that of sesaminol monoglucoside from 5.4 to 19.5 mg with an average value of 8.3 mg. The total content of sesaminol glucoside was 88.3 mg in 100 g of sesame seeds. Also, the sesamolinol content in 100 g sesame seed ranged from 17.6 to 28.5 mg, the average being 20.5 mg. Within     

ANTIOXIDANT POTENTIAL OF TEMPEH AS COMPARED TO TOCOPHEROL

SUMMARY –The antioxidant potential of tempeh to preserve tocopherol-stripped corn oil was studied. Different levels of tempeh were mixed into corn oil, and incubated at 37°C for a maximum of 6 wk. Peroxide values were determined biweekly. Results showed that tempeh can prevent lipid oxidation. Corn oil containing 50% tempeh showed higher antioxidant potential than those containing 25% tempeh, 0.01%α-tocopherol, or 0.03%α-tocopherol. This study substantiates the antioxidant potential of tempeh and suggests its use with other foodstuffs to help preserve the lipids contained therein.     

COMPOSITION OF MAJOR FLAVANONE GLYCOSIDES AND ANTIOXIDANT CAPACITY OF THREE CITRUS VARIETIES

This paper reported on the composition of major flavanone glycosides (FGs) and antioxidant capacity of three Chinese citrus varieties during maturity, namely, Ponkan (P; citrus poonensis Hort. ex Tanaka), Satsuma mandarin (S; citrus unshiu Marc.) and Huyou (H; citrus paradisi Macf. cv. Changshanhuyou). The results showed that citrus peel is a rich source of FGs. Total penolics contents (TPC) of methanol extract of P, S and H were determined. The total antioxidant capacity (TAC) of P, S and H extracts was compared based on vitamin C equivalent antioxidant capacity by 2, 2-diphenyl-1-picrylhydrazyl radical (DPPH·), 2, 2 ' -azinobis (3-ethylbenzothiazoline-6-sulfonate) (ABTS ^·+ ), reducing power and ferric reducing antioxidant power (FRAP) assay. Phenolic compounds may contribute a lot to TAC of fresh fruits, especially for unripe fruits. The correlations among TPC, DPPH·, ABTS ^·+ , reducing power and FRAP assay were rather high ( P <  0.05).

PRACTICAL APPLICATION

Citrus flavonoids are abundant in citrus fruits, especially FGs, such as hesperidin and naringin; and they are attracting more attentions for their biological properties and health benefits. The sun-dried citrus peels ( chenpi ) are usually used in the traditional Chinese medicine for high content of hesperidin. Investigation on the composition of FGs in peel and edible part of citrus fruits during maturity is necessary to establish a database for the future use in health foods and ingredients. Meanwhile, four methods were employed simultaneously to achieve a comprehensive evaluation on the antioxidant capacity of the three citrus varieties. The high antioxidant potential of the three selected citrus varieties made them desirable for dietary prevention of cardiovascular and other diseases.     

POTENTIAL ANTIOXIDANT ACTIVITY OF MARINE RED ALGA GRATELOUPIA FILICINA EXTRACTS

Grateloupia filicina is an important alga cultivated as a source of food in Korea and Japan. In order to examine its potential antioxidant activity, crude extracts of G. filicina were evaluated for their effect on scavenging of reactive oxygen species (DPPH, H, H₂O₂ and O₂) and inhibition of lipid peroxidation. The activities of these extracts were compared with those of commercial antioxidants such as BHA, BHT and α-tocopherol. The methanolic extract (2 mg/mL) of G. filicina scavenged 82% of DPPH radicals which is almost three times higher than that of BHT. The same methanolic extract scavenged 65% of superoxide onion which is almost two times higher than that of BHT and α-tocopherol. In contrast, the extracts in chloroform and carbon tetrachloride inhibited lipid peroxidation more effectively than all commercial antioxidants tested in a linoleic acid model system.     

MICROBIOLOGICAL QUALITY OF HAWAWSHY CONSUMED IN ISMAILIA, EGYPT

The focus of this study was to evaluate the microbial quality of hawawshy from vending shops in Ismailia Province, Egypt. Microbiological analysis of hawawshy resulted in aerobic plate counts from 2 × 10³ to 4 × 10⁶ cfu/g and spore counts from 2 × 10² to 5 × 10⁴ cfu/g. Total coliforms ranged from 3 to 2400 MPN/g while Enterobacteriaceae counts ranged from 6 × 10 to 8 × 10² cfu/g and enterococci counts were 3 × 10³ to 6 × 10⁵ cfu/g. Escherichia coli, coagulase positive staphylococci and fecal streptococci were detected in 17.3, 14.6 and 57.3% of examined samples, respectively. Salmonella spp. was not detected. Different Enterobacteriaceae spp. such as Citrobacter freundi, Enterobacter cloacae, Klebsiella oxytoca, Klebsiella pneumoniae and Serratia liquefaciens were isolated with different percentages. The obtained results indicate that consumption of hawawshy may constitute a public health hazard, and as a consequence, handling practices should require more attention and improvement.     

ANTIOXIDANT POTENTIAL OF ORAL FEEDING OF CYNODON DACTYLON EXTRACT ON DIABETES-INDUCED OXIDATIVE STRESS

The present study is an extension of our previous research work and it deals with the scientific evaluation of antioxidant potential of the aqueous extract of Cynodon dactylon on diabetes-induced oxidative stress of diabetic rats. The most effective dose of 500 mg/kg of extract was given orally to diabetic rats for 30 days. Different oxidative stress parameters were analyzed in various tissues of control and treated diabetic rats. The observed elevated level of LPO comes down significantly ( P <  0.05), and decreased activities of antioxidant enzymes such as CAT, SOD, GPx and GST got increased ( P <  0.05) significantly in diabetic rats on extract treatment. The flavonoids present in the aqueous extract of this plant might be responsible for its marked antioxidant efficacy at tissue level in STZ-induced diabetic rats.

PRACTICAL APPLICATIONS

The Cynodon dactylon has been shown to possess varied medicinal properties. The aqueous extract of the rhizome is used as anti-inflammatory, diuretic, antiemetic, antidiabetic and blood-purifying agent. Recently, it has been reported by our research group that the extract of C. dactylon has hypoglycemic as well as antidiabetic potential. The present communication is an endeavor in the direction of evaluating its in vivo antioxidant effect in STZ-induced diabetic rats so that it can be used as a value-added agent for managing diabetes as well as oxidative stress associated with it.     

抗氧化剂中微胶囊技术的应用及展望

讨论抗氧化剂微胶囊化的意义和研究现状,综述微胶囊技术在食品工业中的应用现状。微胶囊抗氧化剂可提高产品的热稳定性,是应用于油脂和含油脂食品的一种较安全、高效和较低成本的油脂微胶囊抗氧化剂。     

INCIDENCE AND CHARACTERIZATION OF BACILLUS CEREUS IN MEAT AND MEAT PRODUCTS CONSUMED IN TURKEY

A total of 100 retail samples of meat and meat products were examined for Bacillus cereus using mannitol egg yolk polymyxin (MYP) agar as a selective isolation medium. Only 22.4% of the samples contained detectable levels of B. cereus, with counts ranging from log₁₀ 0.69 to 4.80 cfu/g, but a large number of other organisms up to log₁₀ 9.06 cfu/g were sometimes observed on the plates and may have masked the presence of B. cereus or inhibited growth. Two samples of soudjouck contained significant levels of B. cereus, sufficient enough to create a public health hazard. Selected isolates were tested for diarrheal enterotoxin production by a reversed passive latex agglutination (RPLA) test kit. Results showed no difference in the toxin production of B. cereus between beef, ground meat, soudjouck and pastrami samples. Plasmid‐profile analysis and susceptibility to the six commonly used antimicrobial agents were done on selected B. cereus isolates. About 96.4% of the isolates contained plasmids. Plasmid sizes ranged between 2.5 and 3.5 kb. The isolates showed a high rate of resistance to oxacillin (OXA) and amoxicillin (AMC) and a low frequency of resistance to the other antimicrobial agents, with all of them being susceptible to vancomycin (VAN). Approximately 54% of the isolates showed multiple resistance. There was no apparent relationship between drug resistance and carriage of plasmids.     

DETECTION OF PEA FLOUR IN FLOUR OF CHICKPEA BY LACTATE POLYACRYLAMIDE GEL ELECTROPHORESIS1

Polyacrylamide gel electrophoresis was applied to detect adulteration of chickpea flour with pea flour by the presence of extra bands in the unique electro-phoregram of chickpea. Protein extracts prepared by a single extraction with 5M acetic acid produced patterns which were used to differentiate pea and chickpea samples. Using the described procedure, 10 varieties of chickpea did not show intervarietal variation in their electrophoregrams, whereas 11 varieties of pea showed intervarietal differences in their protein composition. However, six of the 25–30 protein bands present in electrophoregrams of most pea varieties can be used as markers for detection of pea flour in chickpea flour. Band 37, present both in chickpea and pea samples, can be used as an internal reference for inter gel comparisons.