Genetic diversity of organoleptic properties in water yam (Dioscorea alata L)

Improving the food quality of yams (Dioscorea spp) is an ongoing challenge to yam breeders and researchers. Forty accessions of D alata were evaluated for the suitability of their tubers for the preparation of two dominant food forms (boiled and pounded) as part of an effort to identify potential parents for use in genetic improvement. Trained panellists were presented with randomised, replicated and coded samples of boiled yam tuber pieces and asked to rate them for mealiness, colour, wetness, softness and taste. The sensory attributes considered for pounded yam (dough from boiled and pounded tubers) were consistency, colour, sheen, smoothness, stickiness, elasticity and hardness. Ratings were based on hedonic scales. Cluster analysis revealed groupings of accessions into eight and nine similarity clusters for boiled yam and pounded yam respectively. The mean scores for general preference were regressed on individual attribute scores. Mealiness, colour and taste were important in the general preference for boiled yam. Consistency, colour and stickiness determined the general preference for pounded yam. Of the accessions, 67% were identified as being suitable for preparation as a boiled vegetable, while 55% were assessed to be good for pounded yam, based on the respective quality attributes evaluated. © 2003 Society of Chemical Industry     

Qualities and antioxidant properties of bread as affected by the incorporation of yam flour in the formulation

Yams (the tubers of Dioscorea spp.) are widely consumed but are also regarded as a medicinal food in China. Traditional Chinese herbal medicines using yams are only available on a seasonal basis, as yams quickly deteriorate during winter storage. Yam (Dioscorea purpurea, a major variety of yams in Taiwan) was freeze‐dried and ground to obtain yam flour. Bread was made by replacing up to 25% of wheat flour with yam flour. Although the loaf volume decreased with the addition of yam flour, the results showed that up to 20% of yam flour could be included in bread formulation without altering the sensory acceptance of the blended bread. The incorporation of yam flour in bread markedly increased the antioxidant capacity of the bread as tested by both DPPH free radical scavenging and total antioxidation tests. Breads containing yam flour can broaden the utilization of yams and may be regarded as possible health‐promoting foods.     

Some characteristics of the roots of the winged bean [Psophocarpus tetragonolobus (L.) DC]

Three accessions of winged bean [Psophocarpus tetragonolobus (L.) DC] tuberous roots from Thailand were examined for their crude protein (N × 6.25), non-protein nitrogen and starch contents. The roots were further analysed for their trypsin inhibitor and urease activities and for the presence of tannins and cyanogenic compounds. Crude protein was found to be high in comparison with other root crops (5.7–6.7% fresh weight) and this contained a high proportion of non-protein nitrogen (7.4–15.0%). Amino acid content of the crude protein, when compared with mature winged bean seeds, revealed a deficiency in the sulphur-containing amino acids but an exceptionally high aspartic acid content. Starch was the major carbohydrate present in the flesh of the roots (21.7–32.1% fresh weight). Root samples were found to contain high levels of trypsin inhibitory activity (13.5–30.1 TIU mg^?1 fresh weight). No urease activity or cyanide could be detected in any of the root accessions studied.     

High‐pressure processing of Manuka honey: brown pigment formation,improvement of antibacterial activity and hydroxymethylfurfural content

This work was undertaken to assess the effects of high‐pressure processing on brown pigment formation, antibacterial activity and hydroxymethylfurfural (HMF) content in Manuka honey. The honey was subjected to different pressures (200–600 MPa) at ambient temperatures (25–33 °C) and with moderate temperatures (53–74 °C) for holding times (10–30 min). The brown pigment formation in high‐pressure‐treated sample showed a significant increase (0.16–0.17, P < 0.05), whereas maximum percentage inhibition of Staphylococcus epidermidis (84.34 ± 7.62%) was achieved when honey was subjected to 600 MPa as compared to the control (64.15 ± 5.86%). The percentage inhibition in high‐pressure‐treated samples correlated linearly (r = 0.941) with brown pigment. No significant increase in HMF as affected by high pressure was found (P > 0.05). Thus, high‐pressure processing has no adverse effect on the honey quality because it can control HMF concentration during process. Increasing brown pigment formation is associated with the enhancement of antibacterial activity.     

Influence of nitrogen form on yield and nitrate content of subirrigated early potato

Potato is classified among the vegetables with low nitrate content but, in diet, it contributes most to the daily intake of nitrate, because of its high per capita consumption. Two trials were carried out in winter–spring and autumn–winter cycles using a trough bench subirrigation system. Potato seedlings were transplanted into pots containing peat, pumice and vermiculite in a 3:1:1 volume ratio. Both trials were carried out to compare three nutrient solutions having the same nitrogen concentration (6.4 mM ), but different ammonium:nitrate (NH₄‐N:NO₃‐N) percentage ratios (100:0, 50:50 and 0:100). In the winter–spring cycle, tubers were lower in weight and were more numerous than in the autumn–winter cycle. The tuber yield of ammonium‐fed plants was lower than with the mixed form and 100% NO₃‐N, but only in the trial carried out in the winter–spring period. Nitrate‐fed plants yielded a number of tubers almost 3‐fold higher than ammonium‐fed plants. The NO₃ content of tubers harvested in spring in the presence of 100% NH₄‐N in the nutrient solution was a 25% of that in nitrate‐fed plants (44 vs 169 mg kg^?1 of fresh mass); in tubers harvested in winter, with worse light conditions, nitrate content increased with increasing NO₃‐N in the nutrient solution (26, 109, and 225 mg kg^?1 of fresh mass with NH₄‐N:NO₃‐N 100:0, 50:50 and 0:100, respectively). The substrate electrical conductivity increased with increasing ammonium concentration in the nutrient solution, and was higher in the upper layer of the substrate. Copyright © 2004 Society of Chemical Industry     

Protein and mineral content of a novel collection of wild and weedy common bean (Phaseolus vulgaris L)

Protein and total calcium, iron, and zinc were determined in 70 accessions of wild and weedy common bean (Phaseolus vulgaris L) from different sites in two Mexican states (Jalisco and Durango). Protein digestibility, essential amino acid profiles, tannins, phytic acid and extractable iron were determined in selected accessions. The phytate/zinc and the phytate × (calcium/zinc) molar ratios were also determined as predictors of zinc bioavailability. For comparative purposes, two cultivated common beans were included. The wild and weedy beans contained more protein and similar protein digestibility compared with cultivated samples. The contents of sulfur amino acids were low in all samples; additionally, beans from Jalisco had higher contents of sulfur amino acids than cultivated ones. Beans from Durango showed higher leucine, valine and aromatic amino acids contents than cultivated beans. Some wild and weedy beans from Jalisco and Durango showed high contents of calcium (7470 mg kg⁻¹), iron (280 mg kg⁻¹), and zinc (33.1 mg kg⁻¹). The phytic acid × (calcium/zinc) molar ratios of some wild and weedy beans were similar to those of cultivated beans. Amounts of extractable iron were in the order of 26–74%. © 2000 Society of Chemical Industry     

Proximate,mineral, amino acid,fatty acid,vitamin E,phytate phosphate and fibre composition of Mimusops zeyheri (Red Milkwood) seed

Mimusops zeyheri, an indigenous tree widely distributed in sub‐Saharan Africa, provides edible fruit. Research on the tree has focused on fruit pulp composition and uses. This study evaluated the nutritional potential of M. zeyheri seed by determining the proximate, fibre and phytate‐phosphate content, the amino acid and fatty acid profiles and vitamin E content of the seed. Dry matter, organic matter, crude protein, ether extract and ash constituted 91.1%, 88.3%, 9.3%, 25.6% and 2.8% of the seed mass respectively. Glutamic acid (1.29 g per 100 g) was the most abundant amino acid. Lysine and phenylalanine were low. Calcium (587.4 mg per 100 g) was the most concentrated macro‐mineral assayed. Gross energy value was 24.34 MJ kg^?1. Lipid yield was 21.3%. Oleic acid was the most abundant fatty acid. Vitamin E concentration was about 2 μg g^?1. Phytate‐phosphate content was 0.03%. Neutral detergent fibre and acid detergent fibre constituted 33.2% and 15.3% respectively. M. zeyheri seed could be exploited as a dietary energy supplement and an oil source rich in oleic acid.     

Quantitative and qualitative analysis of lipids in genetically modified potato tubers with varying rates of 14–3–3 protein synthesis

In six transgenic lines of potatoes with the varying rates of 14–3–3 protein synthesis as well as in control cultivar Desiree the content and composition of the lipids extracted from the mature tubers from three years field trials (1998–2000) were analyzed. The transgenic lines J2 and J1 are both overexpressing gene encoding 14–3–3 protein. The J2 exhibited an overexpression of the protein 14–3–3 derived from pumpkin (Cucurbita pepo) cDNA and in J1 the 14–3–3 overexpression resulted from modifying of ADP‐ribosylation factor synthesis. In the remaining lines, synthesis of the protein 14–3–3 was modified by the antisense technology. In tubers from 1998, the content of total lipids was within the range of 0.45–0.88% of tuber dry matter. The highest amount of fat was in tubers of line J2 (69% more than in the control). The content of lipids in tubers from subsequent years ranged from 0.36 to 0.63% of dry matter. Consistently the highest amount of fat was in tubers of line J2, however, the increase was very slight (8.6% more than in the control). The fractionation of lipids into polar and nonpolar fractions showed that all transgenic lines from field trials 1998 and 2000 contained more nonpolar lipids than the control (up to 270% in line J2). The percentage of nonpolar fractions in fats of tubers from all transgenes harvested in 1999 were similar, but they were higher than in tubers from the previous years, and they amounted to 44.4–49.1%. Chromatographic separation of methyl esters of fatty acids demonstrated that cis‐α‐linoleic acid was the main fatty acid present in potato tubers. This acid composed the biggest part of all lipids in G2 line. In the nonpolar fraction of lipids, palmitic acid followed by cis‐α‐linoleic acid showed the highest amounts.     

Nutritive value of a mixture of tigernut tubers (Cyperus esculentus L.) and baobab seeds (Adansonia digitata L.)

The seeds of baobab (Adansonia digitata L.) and the tubers of tigernut (Cyperus esculentus L.) were analysed chemically for their proximate composition and amino acids. The tubers contained 47.9% digestible carbohydrates, 32.8% oil and 3.8% crude protein. The baobab seeds contained 24.1% digestible carbohydrate, 29.7% oil and 28.4% crude protein. A mixture of the vegetables was prepared from three parts of the tigernuts and one part of baobab seeds, by weight, such that a 10% crude protein meal was obtained. The chemical score of the mixed vegetable was 51%, based on limiting amino acids, i.e. those which contain sulphur. The level of antinutritive substances, such as tannin and tryptic inhibitors, in the raw vegetables were reduced by soaking or boiling.     

Multiplex PCR for the simultaneous detection of Salmonella spp. and Salmonella Enteritidis in food

Multiplex PCR assay (mPCR) for the detection of Salmonella spp. and S. Enteritidis was developed in this study using artificially contaminated chicken carcasses. The assay showed 100% specificity to detect approximately 1 CFU of Salmonella in 10 g of chicken skin after non‐selective enrichment. The mPCR was evaluated in Minas cheese, fresh pork sausage and chicken carcasses commercially available. Salmonella spp. was detected in nine of sixty‐six chicken carcasses, five of fifty‐two cheese samples, and five of fifty‐two sausage samples. The serovar Enteritidis was detected in two samples of contaminated sausage. The mPCR results were confirmed by conventional culture and biochemical identification of the isolates. Serotyping confirmed the presence of S. Enteritidis in sausage samples and showed contamination by serovars Schwarzengrund and Montevideo in chicken carcasses.     

Bile salt deconjugation activity of Propionibacterium strains and their cholesterol co‐precipitation abilities

The present study investigated the deconjugation of bile salts and co‐precipitation of cholesterol with deconjugated bile salts by seven Propionibacterium spp. strains in vitro. Propionibacterium spp. could deconjugate sodium glycocholate (1.53–5.31 mM) and sodium taurocholate (0.08–0.25 mM) bile salts. The highest cholesterol precipitation (47.8 µg/mL) was determined with Propionibacterium freudenreichii subsp. freudenreichii SP3 strain in a 0.15% oxgall‐containing medium. Significant (P < 0.05) correlations were observed between cholesterol co‐precipitation and deconjugation of sodium glycocholate among the strains. In vitro bile salt deconjugation activity studies of P. freudenreichii subsp. freudenreichii SP3 strain revealed that this strain may have potential as a probiotic strain for deconjugation of bile salts in vivo studies.     

Optimising clarification of carrot juice by bacterial crude pectinase

This study was undertaken to search for potential use of crude bacterial pectinase enzyme produced from Bacillus subtilis grown on hazelnut shell hydrolysate in clarification of carrot juice and to optimize the enzyme load, pH and time using the Box–Behnken response surface methodology (RSM). The carrot juice was treated with the crude pectinase enzyme (5.60 U mL^?1) at different concentrations (0.1–0.5%), pH (4–7), and time (2–6 h). The obtained enzyme was also compared with commercial fungal pectinase at identical conditions. RSM provided optimal clarification conditions of 0.5% (w/v) enzyme load, 7.0 pH, and 6 h of time estimating 100% clarity, whose experimental counterpart was 94.47 ± 0.01%. High values of coefficient of determination (R² = 0.9631), predicted R² (0.8989) and insignificant lack‐of‐fit (0.12) also showed that the model was successful in predicting % clarity for various combinations. This study also indicated that crude bacterial pectinase providing about 95% clarity is superior to commercial fungal pectinase, which gave 78% clarity under tested conditions, in terms of clarification ability for carrot juice.     

Rheological and physico‐chemical properties of gelatin extracted from the skin of a few species of freshwater carp

The physico‐chemical and rheological properties of gelatin from the skins of three different freshwater carp species, namely Catla catla, (catla) Cirrhinus mrigala (mrigal) and Labeo rohita (rohu), have been assessed and compared with that of gelatin from porcine skin. The average solids yield from the three species of carp varied in the range of 11.8–14.1%. The amino acid profile showed that the porcine gelatin had a higher proportion of imino acids and glycine than carp skins gelatin. The average molecular weight of carp skins gelatin as determined using a gel filtration technique was 233 kDa, while that of porcine skin gelatin was 282 kDa. The gelling temperature of carp skins gelatin was in the range of 6–15.7 °C, and the melting temperature was 17.9–23.7 °C as determined using a controlled stress rheometer. A higher gelling and melting temperature was observed for porcine skin gelatin.     

Quantitative analysis of allantoin and allantoic acid in yam tuber,mucilage, skin and bulbil of the Dioscorea species

Allantoin and allantoic acid in yam tubers of the D. batatas (Hualien no. 3) and D. pseudojaponica Yamamoto (Keelung) were quantitatively analyzed because the compounds were thought to prevent inflammation and ulcers in humans as well as playing an important role in the storage and translocation of nitrogen in higher plants. To expand yam tuber use, yam tuber mucilage can be used as an ingredient in functional foods and as a skin protectant. The objectives of this research are to analyze the contents of allantoin and allantoic acid in D. batatas and D. pseudojaponica Yamamoto and to compare bubble separation and centrifugation for recovering allantoin and allantoic acid from the mucilage. The total amount of allantoin and allantoic acid of the following Dioscorea (yam) in both the pulp and skin, respectively, were (mean ± RSD, mmoles/g solid): tuber of Keelung yam (D. pseudojaponica Y.) 0.370 ± 6.8%, 1.130 ± 3.4%; tuber of Hualien no. 3 yam (D. batata) 0.278 ± 7.8%, 0.714 ± 9.1%; bulbil of Hualien no. 3 yam (D. batata) 0.179 ± 7.9%, 0.297 ± 3.4%. The Keelung yam was much higher in allantoin and allantoic acid content than the Hualien no. 3. The skin of yam tuber is rich in allantoin and allantoic acid. The allantoin and allantoic acid content is 305% (in Keelung yam) and 257% (in Hualien no. 3) higher than that of the pulp. Bubble separation is an appropriate procedure in the practice for maximum recovery of allantoin and allantoic acid in yams. It was found that 80% of allantoin and allantoic acid yield can be recovered from the low starch contents of mucilage of the Keelung yam using bubble separation.     

Anti-Fenton reaction activity of three taxa of water yam (Dioscorea alata L.)

In the present study, we compared the anti‐Fenton reaction activity of three taxa of water yam (Dioscorea alata L.): DS2, TN2 and PSY [D. alata L. var. purpurea (Roxb.) M. Pouch]. Anti‐Fenton reaction activity was evaluated by measuring the damage inflicted on calf thymus DNA by copper ions combined with hydrogen peroxide with the use of an ethidium bromide binding assay and agarose gel electrophoresis. We found that extracts of tuber pulp from all three taxa of yam had significant anti‐Fenton reaction activity. The protection pattern of the three tuber pulp extracts was similar to that of EDTA, a typical divalent metal ion chelator, which displayed a significant protection lag‐phase. With the use of thin‐layer chromatography, we found that a common, major ansialdehyde‐sulphuric acid stained spot (possibly a polysaccharide mucilage) with an R_f of 0.09 may be the most likely contributor to the anti‐Fenton reaction activities of the yam tuber extracts investigated. The present study identifies the mechanism of the health benefit of the Dioscorea family. The copper‐chelating and absorbing capability of yam tuber pulp extracts may be useful in functional screening.     

Anti-inflammatory activity of American yam Dioscorea trifida L.f. in food allergy induced by ovalbumin in mice

Tropical ecosystems are particularly rich in edible plant species with different bioactive substances. Among the plants with promising benefits for health are species from the genus Dioscorea (Dioscoreaceae), especially those named yam. Recent studies have shown the beneficial effects of different species of Dioscorea, and its main constituent, diosgenine, in the treatment of food allergy. In this study we evaluated the potential of D. trifida, the only yam native from South America, in the treatment of ovalbumin (OVA) induced food allergy in Balb/c mice. HPLC/DAD analysis showed the presence of three very distinctive groups of natural products in extracts and fractions: (I) very polar substances, including allantoin, (II) phenolic substances as flavonoids and phenolic acids and (III) diosgenin and derivatives. Sensitive mice received casein feed with supplementation of crude extract (CE) and fractions. The supplementation with all products from D. trifida reduced IGE, intestinal oedema and mucus production, parameters observed in OVA allergic mice. The results showed the potential of this food to prevent or treat this disease and the necessity to be better explored.     

Chemometrics coupled with ultraviolet spectroscopy: a tool for the analysis of variety,adulteration, quality and ageing of apple juices

This study demonstrates the use of UV spectroscopy (UV) in combination with chemometrics as a simple and feasible approach for analysis of variety, adulteration, quality and ageing of apple juice. The results show that PCA‐UV is adequate to differentiate apple juice varieties and adulteration. The percentage of the adulterant can be detected by PLSR‐UV with RMSE < 0.7783% and R² > 0.9980. For the evaluation of juice quality, PLSR‐UV (RMSE = 0.2555–2.3448; R² = 0.7276–0.9816) is recommended for the prediction of soluble solids, ascorbic acid, total flavonoids, total sugar and reducing sugar, whilst PCR‐UV (RMSE = 0.0000–2.7426; R² = 0.7073–1.0000) is adequate for the prediction of pH and antioxidant activity. In addition, PLSR‐UV may be used to predict the storage time with RMSE = 0.4681 day and R² = 0.9832. Therefore, UV coupled with chemometrics has potential to be developed as a portable tool for the detection of variety, adulteration, quality and ageing of not only apple juices, but also other fruit and vegetable juices.     

Effect of ripening on some physicochemical properties of cooking banana (Musa ABB Cardaba) pulp and flour

Cardaba banana (Musa ABB) pulp and flours were evaluated for changes in some physicochemical properties during ripening. Compositional changes in the pulp showed that ripening significantly (P < 0.05) increased the crude protein (2.48–9.88%), fat (1.33–4.67%), crude fibre (0.80–0.93%), ash (1.66–2.32%) and Vitamin C (12.60–24.28%), while carbohydrate and tannin reduced. Mineral composition varied, following this trend: K > Mg > P > Na > Zn. pH and ‘whiteness’ reduced, while yield, softness index and pulp/peel ratio increased significantly (P < 0.05). Pasting and functional properties of the flours were lowered, however, ripening enhanced better pasting properties. Flours from stages 1–7 could be used as binders, emulsifiers and thickeners, while flours from stages 5–7 may be useful as aerating agents and in preparation of baby formulas and flours from stages 1–2 may be used in bakery products. This investigation proposes the utilisation of the Cardaba banana flour as an industrial raw material and a good substitute to potato, corn or tapioca starches.     

Purification and characterisation of an acid protease from the Aspergillus hennebergii HX08 and its potential in traditional fermentation

A protease AP3 from Aspergillus hennebergii HX08 was purified by ammonium‐sulphate precipitation, followed by anion‐exchange chromatography and gel filtration. The molecular weight of acid protease AP3 was 33 kDa (SDS‐PAGE and MALDI‐TOF‐MS). The protease AP3 was identified as an acid protease with MALDI‐TOF/TOF tandem MS. Its optimal temperature and pH were 60°C and 4.0, respectively. Its K _max and V _max were 57.92 mg/mL and 32.57 U/mL, respectively. The enzyme was active over a broad pH and temperature range (pH 3.0–5.0 and 30–60°C), and exhibited high activity and stability in 2–12% (v /v) ethanol solvent. Subsequent studies suggest that the enzyme presents a relatively high substrate affinity to wheat protein (98% of total activity). Its application to solid‐state fermentation of wheat flour with Saccharomyces cerevisiae could increase the hydrolysis degree of wheat protein (28.26%) and amino acid nitrogen concentration of fermented grains (34.21%). Additionally, enhanced S. cerevisiae biomass (37.09%) and alcohol concentration (38.29%) were also observed during the process. Volatile compounds analysis of fermented grains by headspace solid‐phase micro‐extraction and GC‐MS revealed more flavour compounds. These results suggest its potential in food and alcohol industries. Copyright © 2017 The Institute of Brewing & Distilling