Effect of Different Drying Treatments and Solvent Ratios on Phytochemical Constituents of Ipomoea aquatica and Correlation with α-Glucosidase Inhibitory Activity

Ipomoea aquatica is an aquatic plant that is widely consumed in Southeast Asia as a vegetable. In this study, the influence of various ethanol ratios (0, 20, 50, 80, and 100%) as an extraction solvent and different drying methods including air drying, sun drying, and oven drying on phytochemical constituents of I. aquatica was investigated using a proton nuclear magnetic resonance-based metabolomics approach. The effect on α-glucosidase inhibitory activity and total phenolic content was also examined. Clear discrimination was observed between different ethanol ratios and different drying processes by principal component analysis. The highest α-glucosidase inhibitory activity was observed for absolute ethanol extract from the oven drying method with IC₅₀ value of 204.0 ± 59.0 µg/mL and total phenolic content value of 22.0 ± 0.7 µg gallic acid equivalent/mg extract. Correlation between the α-glucosidase inhibitory activity and the metabolite were analyzed using a partial least square analysis. The metabolites that are responsible for the activity were quercetin derivatives, chlorogenic acid derivatives, sucrose, and fructose. This study highlights the basis for future investigations of I. aquatica as a source of food that has the potential for nutraceutical enhancement and as ingredient in medicinal preparation.     

Effects of extended dry storage of powdered infant milk formula on susceptibility of Enterobacter sakazakii to hot water and ionizing radiation

Infant milk formula has been identified as a potential source of Enterobacter sakazakii, which has been implicated in neonatal meningitis and necrotizing enterocolitis. This study was undertaken to determine whether the length of E. sakazakii storage in powdered infant milk formula (PIMF) affected the ability of the pathogen to survive subsequent reconstitution of the powder with hot water or treatment with gamma radiation. Five E. sakazakii strains were mixed individually with PIMF and kept for up to 12 months at 25 degrees C. After storage PIMF was reconstituted with water at 60 to 100 degrees C or was exposed to < or = 5 kGy of gamma radiation. Without any treatment secondary to drying, E. sakazakii counts decreased < 1 log/g after 1 month but decreased about 4 log/g during storage for 8 to 12 months. Dry storage decreased thermal resistance but increased resistance of E. sakazakii to ionizing radiation in PIMF. Reconstitution of contaminated powder with water at 70 degrees C after 1 month of dry storage reduced E. sakazakii viability slightly, > 2 log/g, and after powder was stored for 12 months all E. sakazakii strains were eliminated. In contrast, desiccation substantially increased the resistance of E. sakazakii strains to ionizing radiation. Although the D-value for E. sakazakii IMF1 following overnight storage in PIMF was 0.98 kGy, > 4 kGy was required to kill 1.5 log/g of the same strain that had survived 12 months in dry PIMF. Results suggested that low-dose irradiation will more effectively eliminate E. sakazakii from PIMF if the treatment is applied shortly after PIMF manufacture.     

Nutritive value of mango seed kernel

Seed kernels of two cultivars (Chausa and Dusheri) of mango (Mangifera indica) were analysed for chemical composition, lipid classes, fatty acid composition, amino acid profile and chemical evaluation of protein quality. The seed kernels constituted about 18% of the total fruit and had 5% protein, 6–7% crude fat, 0.19–0.44% tannins, iodine value of 34–44 and saponification number 202–213. Oleic acid (42%) and stearic acid (39%) were the principal fatty acids in the oil. The in vitro digestibility was low in these cultivars, possibly due to the presence of tannins. Sulphur-containing amino acids (methionine+cystine) and isoleucine were the limiting amino acids in Chausa and Dusheri, respectively. The essential amino acid index and protein quality index were high, thus indicating the good quality of the protein in mango seed kernel.     

Nutritional constituents and antioxidant properties of indigenous kembayau (Dacryodes rostrata (Blume) H. J. Lam) fruits

The nutritional and antioxidant properties of peels, pulp and seeds of kembayau (Dacryodes rostrata) fruits were evaluated. Kembayau seeds and pulp were rich in fat, while peels had the highest ash contents. Potassium was the most prevalent mineral in peels (380.72-1112.00 mg/100 g). In kembayau fruits, total flavonoid content (1012.74-28,022.28 mg rutin equivalent/100 g) was higher than total phenolic and total monomeric anthocyanin contents. Kembayau seeds exhibited high flavonoid and phenolic contents compared to the contents in peels and pulp. Antioxidant capacities were also higher in seeds as typified by trolox equivalent antioxidant capacity assay (51.39-74.59 mmol TE/100 g), ferric reducing antioxidant power assay (530.05-556.98 mmol Fe²⁺/100 g) and by 1,1-diphenyl-2-picryl hydrazyl radical scavenging activity (92.18-92.19%) when compared to peels and pulp. Pulp and peels of kembayau fruit may be an important source of energy and minerals for human consumption, while seeds have a good potential as antioxidants.     

Hypoglycemic effects of cocoa (Theobroma cacao L.) autolysates

Fat, alkaloid and polyphenol contents of two clones of cocoa (UIT1 and PBC 140) were removed and the remaining powder was autolyzed at pH 3.5 and 5.2. Based on the results, autolysates of UIT produced at pH 3.5 exhibited the highest ability to inhibit α-amylase activity. However, no α-glucosidase inhibition activity was observed under the conditions specified. Autolysates produced under pH 3.5 caused the highest amount of insulin secretion. In streptozotocin-diabetic rats, all cocoa autolysates significantly decreased blood glucose at 4 h. To assure that the results from the assays were not due to the polyphenols of cocoa autolysates qualitative and quantitative tests were applied. According to their results cocoa autolysates were found to be free from polyphenols. Analysis of amino acid composition revealed that cocoa autolysates were abundant in hydrophobic amino acids. It can be suggested that besides other compounds of cocoa, its peptides and amino acids could contribute to its health benefits.     

Enzyme activity and biochemical changes of three date palm cultivars with different softening pattern during ripening

The physicochemical composition changes during palm ripening were studied. The activities of invertase and cell wall-modifying enzymes, namely pectin methylesterase (PME), β-galactosidase (β-Gal), endo-1,4-β-d-glucanase (EGase), and cellulase were monitored during growth and ripening of Shahani, Piarom and Deiry cultivars with different textures. Also, we estimated the concentrations of six organic acids by HPLC. Reducing sugars, most of organic acid, pH and TSS increased up to the full-ripe stage of all date types. On the contrary, moisture, macro and microelements and proteins decreased during the same period. Despite a considerable rise in invertase activity (200 units) during ripening of Shahani, no significant trend could be discerned in Deiry cultivar (8 units) at different stages. Our results also showed that cell wall enzymes were increased in activity during ripening and these increases were coincident with fruit softening. Furthermore, our results showed that the composition and the variation of the chemical compositions mainly depended on the cultivar and maturity stage.     

Evaluation of the chemical composition and antimicrobial activity of Mentha pulegium,Juniperus phoenicea,and Cyperus longus essential oils from Morocco

The present study evaluates the chemical composition and antimicrobial activity of the essential oils (EOs) of Mentha pulegium L., Juniperus phoenicea L. and Cyperus longus L. from Morocco. The composition of these species was analyzed by GC/MS and 84 components were identified. M. pulegium EO showed a great similarity with EOs coming from other regions, as pulegone, the major component, accounted for about 70% of the EO. The EO of J. phoenicea had as main components α-pinene (24.9%), β-phellandrene (24.4%) and α-terpinyl acetate (12.9%). The EO extracted from C. longus was remarkably rich in sesquiterpene hydrocarbons (83.2%), which included β-himachalene (46.6%), α-humulene (16.9%), and γ-himachalene (10.1%). The antimicrobial activity of these EOs has been evaluated against seven bacteria of significant importance for food hygiene. According to the results, M. pulegium showed the best bacteriostatic and bactericidal effect, followed by J. phoenicea and C. longus. So far as we know, this is the first report on the quantitative composition and biological activity of the essential oil from C. longus. The tested EOs showed a variable degree of antimicrobial activity being M. pulegium the most effective one.     

Inhibition of Listeria monocytogenes on bologna sausages by an antimicrobial film containing mustard extract or sinigrin

The ability of Listeria (L.) monocytogenes to convert glucosinolates into antimicrobial isothiocyanates was investigated. Mustard glucosinolates in pure (sinigrin) or extract forms (sinigrin, oriental; sinalbin, yellow mustard) were used in broth media and in a polyvinyl polyethylene glycol graft copolymer (PPG) packaging film with bologna to examine their value as antimicrobial precursors for the control of L. monocytogenes viability and extension of bologna shelf-life at 4 °C. During broth tests with deodorized (myrosinase-inactivated) mustard extracts (10 d at 20 °C) or with purified sinigrin (21 d at 20 °C) L. monocytogenes was only inhibited when exogenous myrosinase was added. None the less, the organism was able to hydrolyze almost half the pure sinigrin by 21 d in tests without added enzyme. Reductions in sinigrin levels were measured by reversed-phase liquid chromatography, and in the absence of L. monocytogenes or added myrosinase the glucosinolate was stable. When pure sinigrin, oriental or yellow mustard extracts were incorporated in PPG films containing 3, 5 and 6% (w/w) of the corresponding glucosinolate and used to package bologna inoculated with 4 log CFU/g L. monocytogenes, the pathogen became undetectable in bologna packed with the oriental mustard extract at 52 d storage and remained undetectable at 70 d. The yellow mustard extract was less inhibitory and the pure sinigrin was not antimicrobial. L. monocytogenes numbers reached >7 log CFU/g in the film and untreated controls at 17 d storage. At 35 d storage, samples packed with control film contained sufficient numbers of lactic acid bacteria (LAB) (>7 log CFU/g) to be considered spoiled, whereas treatments containing mustard or sinigrin remained <7 log CFU/g LAB for ≤ 70 d. L. monocytogenes played a key role in exerting control over its own viability in bologna by hydrolysis of the glucosinolate in the oriental mustard film, but other antimicrobials in treatments may have contributed.     

Compositional changes in whole grain flours as a result of solvent washing and their effect on starch amylolysis

Whole grain flour is used most often as raw material for fuel alcohol production. However, the dry-milling process and the non-starch components of flours may impact the enzymatic hydrolysis of starch to glucose. The particle size distributions of flours prepared from whole grain triticale, barley, wheat and corn were determined and the effects of pre-washing with water, hexane, 100% ethanol or 50% ethanol on flour composition and the amylolysis of starch were studied. Scanning electron microscopy of the flours revealed that grinding grain to pass a sieve with an aperture size of 0.5 mm effectively released starch granules from endosperm cells. Pre-washing with water or 50% ethanol decreased the protein, phytic acid and total free phenolic contents of flours and, except for corn flour, increased starch content. Pre-washing with water reduced the ash contents of all flours, and reduced the ??-glucan content of barley flour by 98%. Pre-washing with hexane or 100% ethanol removed much of the lipid from the flours. Pentosan content was affected only slightly by any of the pre-washing treatments. Each of the pre-washings was associated with a significant change, positive or negative, in the extent of ??-amylolysis for one or more of the flours. The degree of ??-amylolysis in unwashed flours ranged from 22.4 to 26.1%, and from 21.6 to 28.1% in pre-washed flours, varying with flour source and solvent treatment. Pre-washing of flours increased the degree of hydrolysis achieved with sequential ??-amylase/amyloglucosidase treatment, with values ranging from 61.4 to 72.8% in pre-washed flours compared to 56.2-57.8% in unwashed flours. The highest degrees of hydrolysis were achieved with 50% ethanol pre-washing (72.4 and 72.8% for triticale and barley flours, respectively). The degree of ??-amylase/amyloglucosidase hydrolysis obtained for isolated starches ranged from 83.7 to 93.0%. This study demonstrated clearly that the partial removal of non-starch components from whole grain flours by solvent pre-washing enhanced the degree of amylolysis of starch.