Zinc Fertilization Increases Ascorbic Acid and Mineral Contents of Potatoes

The effects of zinc fertilization on ascorbic acid and mineral concentration of Katahdin potatoes were investigated over 2 yr. During the first year zinc sulfate (ZnSO₄) was banded during planting at rates from 11.2 to 224 kg/ha in two locations in New York. During the second year ZnSO₄ was banded during planting at rates of 0, 22.4, 44.8 and 112 hg/ha at one of the locations. Ascorbic acid content of tubers was higher only with the 112 kg/ha ZnSO₄ treatment. Zinc fertilization resulted in higher Zn concentration in tubers during both years and at both locations. Zinc fertilization increased amounts of Ca, Mn, Cu, Al and Co but did not affect Cd content in potato tubers.     

Surface pasteurization of fresh pomelo juice vesicles by gaseous chlorine dioxide

This study developed an in-package pasteurization method that released gaseous chlorine dioxide (ClO₂) triggered when moisture vapor from the fresh produce interacted with a ClO₂ precursor. The samples were placed in sealed containers (750 ml) containing mixtures (0.1–1.0 g) of sodium chlorite and citric acid powders (1:1) and treated for up to 15 min at 25°C. Our results showed that, production of gaseous ClO₂ was linearly correlated with the reaction time (R²>0.95) with mean concentrations in the range of 1.70 – 8.66 mg/L. The gaseous ClO₂ treatments for 15 min significantly reduced Escherichia coli and fungi populations on pomelo juice vesicles with reductions of 6 and 2 log CFU/g, respectively. Perchlorate and chlorite in samples were not detected, and chlorate was only detected when the mean ClO₂ concentration was over 4.09 mg/L. The treatments did not significantly affect total soluble solids, total acids, pectin and malondialdehyde contents, and color of pomelo juice vesicles. The contents of ascorbic acid, naringin, and limonin, and bitterness score decreased with the increase of mean ClO₂ concentrations. Overall, our results demonstrate an effective nonthermal approach for microbial inactivation while maintaining the quality of fresh pomelo juice vesicles.     

Effects of iron and zinc foliar applications on rice plants and their grain accumulation and grain nutritional quality

BACKGROUND: Foliar sprays of iron (Fe) and zinc (Zn) fertilisers are known to be an effective way to improve Fe and Zn concentrations in rice grain. However, results can differ significantly among different rice cultivars and/or types of foliar fertiliser. In this study, several Fe‐rich rice cultivars were used to identify an effective foliar fertiliser for optimal Fe and Zn enrichment of rice grain. RESULTS: Foliar Fe amino acid (Fe‐AA) fertiliser significantly improved the Fe concentration in brown rice of most cultivars. Compared with the control, the average Fe concentration in all tested cultivars was increased by 14.5%. The average Fe concentration was increased by 32.5% when 1% (w/v) nicotianamine (NA) was added to Fe‐AA, while the average Zn concentration was increased by 42.4% when 0.5% (w/v) ZnSO₄ · 7H₂O was added to Fe‐AA. CONCLUSION: The results suggested that NA at a suitable concentration added to Fe‐AA fertiliser could accelerate Fe accumulation in rice grain. A relatively low concentration of ZnSO₄ · 7H₂O added to Fe‐AA significantly increased Fe and Zn accumulation in rice grain. The study identified some useful foliar fertilisers for enhancing the levels of Fe and Zn in selected Fe‐rich rice cultivars. Copyright © 2012 Society of Chemical Industry     

Metal binding novel flaxseed peptides (linusorbs)

Linusorbs (LOs; a.k.a. cyclolinopeptides) are naturally occurring orbitides derived from flaxseed. These compounds consist of 8–10 amino acid residues, which are linked via an N ‐ to C‐terminal peptide bond with molecular masses of approximately 1 kDa. The LO circular structure makes them candidates for metal binding studies. Flaxseed extracts are known to suppress Pb and Cd toxicity. Hence, four metal salts surveyed include Zn(CH₃COO)₂, ZnSO₄, Pb(CH₃COO)₂ and Cd(NO₃)₂ with pure LOs 1–5 . Proton NMR spectra indicated interaction of LOs with metal salts in solution and were used to determine impacts of methionine oxidation on interactions with metal ions. The methyl group of methionine S,S ‐ dioxide of related LOs did not show the same shift in the presence of Zn(CH₃COO)₂ and Pb(CH₃COO)₂ observed in their methionine S ‐ oxide analogues. Metal complexes were observed forming at 10^?2 m to 10^?4 m but not at lower concentrations (10^?5 m to 10^?8 m ). Mass spectrometry data confirmed that metal binding strength varied by metal in the order Zn(CH₃COO)₂<Pb(CH₃COO)₂<ZnSO₄<Cd(NO₃)₂.     

Efficacy of Pork Loin as a Source of Zinc and Effect of Added Cysteine on Zinc Bioavailability

Based upon Zn uptake in chick tibia, Zn in raw and cooked pork loin was about 40% more bioavailable than that in ZnSO₄-H₂O. Neither roasting nor braising affected Zn bioavailability in the loin preparations. Adding 0.40% cysteine to diets containing ZnSO₄ improved Zn bioavailability by 73%. Pork loin is an excellent source of bioavailable Zn, and SH-containing compounds such as cysteine and glutathione that are present in meat may contribute to enhanced gut absorption of meat-source Zn.     

Antimicrobial efficacy of gaseous chlorine dioxide against Salmonella enterica Typhimurium on grape tomato (Lycopersicon esculentum)

The aim of this study was to investigate the effects of gas level and treatment condition on antimicrobial efficacy of ClO₂ gas against Salmonella enterica Typhimurium on grape tomato (Lycopersicon esculentum). Grape tomatoes were dip‐inoculated with inoculum of S. enterica Typhimurium TISTR 292 (ATCC 13311) (9.79 ± 0.39 log CFU mL^?1) and allowed to dry before treatments. The pre‐inoculated samples were exposed to 0.15–0.85 mg of ClO₂ gas, for up to 58 min. The treatments at 4 and 25 °C resulted in population reductions of S. enterica Typhimurium of up to 3.95 ± 0.22 and 7.37 ± 0.39 log CFU per fruit, respectively. The population reduction results were used to construct statistical models to predict efficacy of ClO₂ gas. The second‐order equations for treatments at 4 and 25 °C had R² of 0.87 and 0.95, respectively, and indicated that efficacy of ClO₂ gas was significantly influenced by ClO₂ gas level, exposure time and treatment temperature.     

Chlorine dioxide treatment decreases respiration and ethylene synthesis in fresh‐cut ‘Hami’ melon fruit

The effects of chlorine dioxide (ClO₂) on respiration and ethylene synthesis of fresh‐cut melon fruit and the possible mechanisms involved were investigated. Fresh‐cut ‘Hami’ melon fruit fumigated with gas ClO₂ in sealed container for 12 h and then stored at 5 °C with 95% relative humidity (RH) for 19 days. Results showed that fruit treated with ClO₂ resulted in lower rates of the total respiration, alternative pathway respiration, cytochrome pathway respiration and ethylene production. Furthermore, the expressions of ethylene biosynthesis‐related genes, including CmACS2, CmACO1 and CmACO3 were reduced by ClO₂ treatment. Taken together, it is suggested that ClO₂ treatment might be an effective way to delay ripening of fresh‐cut ‘Hami’ melon, partially due to the reduced respiration and ethylene biosynthesis.     

Impact of zinc salts on heat-induced aggregation of natural actomyosin from yellow stripe trevally

Impact of zinc sulphate (ZnSO₄) and zinc chloride (ZnCl₂) on heat-induced aggregation of natural actomyosin (NAM) extracted from yellow stripe trevally (Selaroides leptolepis) was investigated. In the presence of ZnSO₄ or ZnCl₂, the transition temperature (T_max) of myosin shifted from 47.83 ± 0.30 °C to 46.05 ± 0.36 and 46.49 ± 0.49 °C, with the coincidental decreases in ΔH from 1.07 ± 0.03 J/g to 0.63 ± 0.02 and 0.67 ± 0.04 J/g, respectively (P < 0.05). Additionally, Ca²⁺–ATPase activity of NAM decreased with increasing the concentrations of ZnSO₄ or ZnCl₂ during heating up to 40 °C. During heating from 20 to 75 °C, higher turbidity, surface hydrophobicity and disulphide bond formation were obtained in NAM added with ZnSO₄ or ZnCl₂ at temperatures ranging from 40 to 75 °C, compared with the control. Nevertheless, a higher aggregation was found in NAM added with ZnSO_4, compared with ZnCl_2. Zeta potential (ζ) analysis suggested that the surface of NAM added with ZnSO₄ became less negatively charged, compared with that of ZnCl₂ counterpart. Transmission electron microscopy showed that the structure of NAM was highly interconnected, finer and denser when zinc salts, especially ZnSO₄ were incorporated. Therefore, ZnSO₄ could be used to induce aggregation of fish muscle proteins, thereby improving gelling property of fish mince or surimi.     

Production of fungal biomass from cormel process waste‐water of cocoyam (Xanthosoma sagittifolium (L) Schott) using Aspergillus oryzae obtained from cormel flour

Aspergillus oryzae obtained from spoilt cormel flour was subjected to mutation treatments using X‐rays, solar radiation and bleach. Exposure of A oryzae spores to X‐radiation of 50 kV at 20 mA s and other treatments induced both mutation and lethality in the organism. Following selection and screening of viable colonies on a medium containing cormel process waste‐water as the only carbon source, two strains, A oryzae No 15 and A oryzae No 8, which significantly (P ≤ 0.05) produced more biomass at a higher growth rate than the wild parent, were chosen for single‐cell protein production. Nutrient content of the single‐cell protein produced by the mutants was comparable to that of the wild type. Addition of 3.0 g each of (NH₄)₂SO₄, NH₄NO₃, NH₄Cl, and urea in 1 l of Xanthosoma process waste‐water increased the growth rate of mutants, with the highest increase observed with urea. Medium amended with urea also produced fungal biomass with the highest protein level of 7.97 g l^?1 for A oryzae No 8 strain compared with a protein yield of 3.97 g l^?1 obtained in the control. Total biomass produced after 54 h was 22.47 g l^?1 for A oryzae No 15 strain when urea was added, whereas only 15.20 g l^?1 was produced when no nitrogen source was added. The optimal temperature for single‐cell protein production was found to be 35 °C and the optimal pH was 3.50. A speed of 100 rpm gave the largest quantity of fungal biomass for the mutants tested. Copyright © 2003 Society of Chemical Industry     

Baroprotective effect of increased solute concentrations on yeast and moulds during high pressure processing

The baroprotective effect of increasing solute concentrations on yeast cells and fungal conidia subjected to high pressure processing (HPP) was studied. Suspensions of yeast cells (Saccharomyces cerevisiae, Pichia anomala and Hanseniaspora uvarum) or fungal spores (Penicillium expansum, Fusarium oxysporum and Rhizopus stolonifer) in citrate phosphate buffer formulated with sucrose at 40, 50 and 60 °Brix, or with glycerol and NaCl at equivalent water activity (a_w) values (0.925, 0.903 and 0.866 a_w) were subjected to 600 MPa pressure for varying times, and then were enumerated by spread plate technique to assess survival. There was an increasing resistance to inactivation by high pressure with an increase in solute concentration. The two moulds with easily wetted spores, R. stolonifer and F. oxysporum, showed strongest resistance to HPP at 0.866 a_w. Differing responses to the three solutes were observed among the fungal species tested, indicating that the chemical nature of the solute may also be important in protecting yeasts and moulds during and after pressure treatment. Sucrose had a stronger baroprotective effect for S. cerevisiae than the other solutes, at two of the three investigated a_ws. For P. expansum at 0.903 a_w, NaCl gave the best protective effect. Scanning electron microscopy of HPP treated cells showed the protective effects of increased sucrose concentration. The results reported here have practical implications for the food industry in the application of HPP for production of fruit preparations or syrups, and should be taken in account in establishing efficient process design.

Industrial relevance

As high concentrations of sugar, salt and glycerol provide protection for yeasts and moulds during high pressure processing, foods containing high levels of solutes may need longer processing times or higher pressures to achieve inactivation of these fungi.     

Combined use of UV‐C irradiation and heat treatment to improve postharvest life of strawberry fruit

The effects of UV‐C (4.1 kJ m^?2) and heat treatment (45 °C, 3 h in air) either separately or combined on the quality of strawberries (Fragaria × ananassa cv Seascape) at the 75 or 50% surface red ripening stage were assessed, the latter stage being used only in the firmness test. In addition, the development of surface fungal infections was followed and in vitro germination assays on conidia of Botrytis cinerea and Rhizopus stolonifer performed. Both heat and combined treatments, decreased hue and delayed changes of the L* parameter. All treatments reduced the accumulation of anthocyanins. Control fruit softened most while fruit treated by the combined method were the firmest. The combined treatment reduced fungal infections and delayed in vitro germination of Botrytis cinerea conidia. After 2 days at 20 °C, treated fruit had lower amount of phenolics than the control. Neither the heat nor UV‐C irradiation modified the total sugar content, although the combined treatment decreased it slightly relative to the control. Titratable acidity increased through storage at 20 °C in all fruit, but no differences between control and treated fruit were detected. The combination of UV‐C and heat treatments enhanced the benefits of applying each treatment separately, and could be useful to improve and extend strawberry fruit postharvest life. Copyright © 2004 Society of Chemical Industry     

Antagonism of Trichoderma or Gliocladium Species on Two Phytopathogenic Species of Fusarium

SUMMARY

The antagonistic actions of Trichoderma and Gliocladium species against two phytopathogenic species of Fusarium (a serious disease in cotton production) were studied in vitro. The antagonist induced a substantial lysis of mycelium of the target fungi which became malformed and thickened. Bulging or swollen hyphal strands occurred and sometimes with clamydospores production. Antagonists produced chitinase and β-1,3-glucanase in liquid culture contained cell wall of Fusarium spp. as a sole carbon source. Crude enzyme preparations of the antagonists with lytic enzyme activities greatly reduced the germinated conidia of Fusarium spp. Moreover, aberrant morphology of conidia was observed with germ tube lysis. On the other hand, the resulted mycelia showed wilt mycelium, coagulated protoplasm, heavy vacuolization and swelling followed by the complete destruction of the hyphae.     

Key properties of iodine‐, iron‐ and zinc‐ fortified fish cracker: effects of ambient shelf storage on iodine retention and quality indicators

Multi‐micronutrient (MN)‐fortified fish cracker could be used as a means to improve iodine, iron (Fe) and zinc (Zn) status. We evaluated iodine stability as well as the quality and sensory properties of MN‐fortified fish cracker, at the fortification levels of 5.3 mg per 100 g for Fe and Zn and 260 μg per 100 g for iodine in the dough. On average, the overall retention of iodine after processing and storage for 4 months was ~65%. Fortification with KIO₃ + ZnO, or KIO₃ + ZnO + ferrous fumarate, significantly increased the loss of iodine during processing. The Fe compounds tended to promote iodine instability during storage and contributed to thiobarbituric reactive substances. Fortification did not affect linear expansion of the cracker. Triple‐fortified fish cracker with KIO₃, ferric pyrophosphate and ZnO exhibited both high iodine retention (92.7% for steaming + drying and 72.7% for storage) in the tropical conditions (30 ± 1 °C, 80 ± 5% R.H.) and achieved overall desirable sensory scores. Thus, such fortification of fish cracker might successfully supplement iodine, zinc and iron, while at the same time contributing to the palatability of cracker.     

Chitosan nanoencapsulation of Pogostemon cablin (Blanco) Benth. essential oil and its novel preservative effect for enhanced shelf life of stored Maize kernels during storage: Evaluation of its enhanced antifungal,antimycotoxin, antioxidant activities and possible mode of action

The present evaluation aimed to synthesis and characterise the Pogostemon cablin essential oil encapsulated chitosan nanoemulsion (PCEO-CN) and evaluated its antifungal antimycotoxin and antioxidant activities. A total of twenty-six different chemical compounds were identified from P. cablin essential oil (PCEO), among which patchoulol (34.93%), α-bulnesene (17.76%) and α-guaiene (15.44%) were recorded as major components. The average size of PCEO-CN was 18.20 nm. The PCEO-CN showed concentration-dependent broad-spectrum antifungal and antimycotoxin activities. The in vivo evaluation showed that PCEO-CN significantly protected maize seeds from mould-induced biodeterioration and aflatoxin B₁ biosynthesis for up to 30 days. The PCEO-CN significantly inhibits ergosterol biosynthesis and cellular integrities of A. flavus. Based on the present study, PCEO-CN could be used as a food preservative to control mould and mycotoxin contamination in stored maize.     

Removal of zinc residues from apple leaves by hydrochloric acid and leaching of other nutrients in the process

Leaves sampled from “Lord Lambourne”, “Starking Delicious” and “Golden Delicious” apple trees sprayed with zinc sulphate were treated in various ways (a detergent wash, an acid wash, a 10 min, or a 20 min soak in N-HCl). Leaves which were soaked had the lowest zinc content, and this was attributed to “internal” zinc; the other treatments left behind more zinc, and the increase was attributed to “external” and/or easily leachable zinc. A single spray (0.3% ZnSO₄. H₂O) increased “internal” zinc contents to ～50 parts/10⁶, and three sprays to ～150 Parts/10⁶. Soaking the leaves in N-HCl for 10 min leached out K, Mg and Mn but not N, P or Fe. As with zinc, soaking for 20 min did not, except in one case, leach out any additional amounts of nutrients. It is suggested that there may be an “easily leachable” fraction of K, Mg, Mn, and possibly Zn, which is removed from the leaves by the 10 min soak in N-HCl.     

Inactivation of Bacillus cereus Spores on Red Chili Peppers Using a Combined Treatment of Aqueous Chlorine Dioxide and Hot‐Air Drying

The effect of a combined treatment using aqueous chlorine dioxide (ClO₂) and hot‐air drying to inactivate Bacillus cereus spores on red chili peppers was evaluated. Ten washed and dried pepper samples, each comprising half of a single pepper (Capsicum annuum L.), were inoculated with B. cereus spore suspension. The inoculated samples were washed with sodium hypochlorite (NaOCl; 50, 100, or 200 μg/mL) or ClO₂ (50, 100, or 200 μg/mL) solution for 1 min and then air‐dried (25 ± 1 °C, 47 ± 1% relative humidity), which was followed by drying with hot air at 55 °C for up to 48 h. The spore populations on the samples were enumerated and their a_w and chromaticity values were measured. The spore numbers immediately after treatment with NaOCl and ClO₂ were not significantly different. A more rapid reduction in spore numbers was observed in the samples treated with ClO₂ than those treated with NaOCl during drying. A combined treatment of ClO₂ and hot‐air drying significantly reduced the spore populations to below the detection limit (1.7 log CFU/sample). B. cereus spores on chili peppers were successfully inactivated by washing with ClO₂ solution followed by hot‐air drying whereas the pepper color was maintained.     

Zinc‐loaded whey protein nanoparticles prepared by enzymatic cross‐linking and desolvation

Zinc‐loaded whey protein nanoparticles were prepared by enzymatic cross‐linking whey protein followed by ethanol desolvation. Whey protein isolate (WPI) was denatured by heating (80 °C for 15 min) at pH 7.0 and then cross‐linked by transglutaminase at 50 °C for 4 h while stirring. Transglutaminase was inactivated by heating at 90 °C for 10 min, and then, ZnSO₄·7H₂O (1–10 mm ) was added. Zinc‐loaded whey protein nanoparticles were formed by adding ethanol at one to five times the volume of the protein solution at pH 9.0. The desolvated solutions were diluted by adding distilled water at ratio of 1:100 (w/v) immediately after desolvation. Dynamic light scattering (DLS) data showed that the particle size of zinc‐loaded whey protein nanoparticles increased with the amount of zinc and the volume of ethanol. Scanning electron microscopy micrographs revealed an almost spherical morphology for zinc‐loaded whey protein nanoparticles. The zinc loading efficiency was determined ranging from 76.7% to 99.2%. In vitro test data showed that the zinc release rate was low in simulated gastric fluid but high in simulated intestinal fluid. The results indicated that enzymatic cross‐linked whey protein nanoparticles may be used as a good vehicle to deliver zinc as a supplement.     

Effects of combined nonthermal treatment on microbial growth and the quality of minimally processed yam (Dioscorea japonica Thunb) during storage

The effects of combination treatment with aqueous chlorine dioxide (ClO₂) and ultraviolet‐C (UV‐C) on the quality of yams were examined. Yam samples were treated with distilled water, 50 ppm aqueous ClO₂, 5 kJ m^?2 UV‐C or a combination of 50 ppm aqueous ClO₂ and 5 kJ m^?2 UV‐C. The microbiological analysis of the yams after aqueous ClO₂ treatment, UV‐C irradiation or combination treatment indicated significant reductions in the populations of pre‐existing microorganisms. In particular, the combination treatment reduced the populations of total aerobic bacteria, yeast and mould, and coliform bacteria in the yams by 3.2, 3.4 and 3.8 log CFU g^?1, respectively. The combination treatment also maintained the colour of the yams during storage. Sensory evaluation results indicated that the qualities of the yams treated with the combination of aqueous ClO₂ and UV‐C were better than those of the other treatments. These results clearly indicate that combination treatment with aqueous ClO₂ and UV‐C could be useful in improving the microbial safety and extending the shelf life of the yams.     

Alternative Sanitizers to Chlorine for Use on Fresh‐Cut “Galia” (Cucumis melo var. catalupensis) Melon

ABSTRACT: Chlorine is commonly used to reduce microbial load in fresh‐cut vegetables. However, the production of chlorinated organic compounds, such as trihalomethanes, which are potential carcinogens, has created the need to investigate the efficiency of nontraditional sanitizers and alternative techniques. The effects of 4 novel sanitizers were tested in fresh‐cut “Galia” melon: chlorine dioxide (ClO₂) at 3 mg/L, peracetic acid (PAA) at 80 mg/L, hydrogen peroxide (H₂O₂) at 50 mg/L, and nisin at 250 mg/L plus EDTA 100 mg/L (nisin + EDTA). A chlorine treatment (NaOCl at 150 mg/L) was used as a control. Pieces of melon were packed in polypropylene trays under passive modified atmosphere (3 to 4 kPa of O₂ and 10 to 11 kPa of CO₂) and stored up to 10 d at 5 °C. Microbial growth, firmness, respiration rate, gas composition, sensory evaluation, color, total soluble solids (TSS), and tritable acidity (TA) were evaluated at days 0, 7, and 10. The novel sanitizers PAA, H₂O₂, and nisin + EDTA, in the studied concentrations, reduced the microbial growth to a more efficient range than chlorine and ClO₂. In addition, those sanitizers delayed softness, did not affect the respiration rate, SST, or AT. The sensorial parameters were kept above the upper limit of marketability and they did not impart an “off flavor.” These sanitizers maintained quality and shelf life of fresh‐cut Galia melon for 10 d of storage at 5 °C. Nevertheless, other concentrations, in particular for ClO_2, could be tested to study an extended shelf life in melon pieces.     

Bioactive xanthones from the roots of Hypericum perforatum (common St John's wort)

BACKGROUND: Extracts of Hypericum perforatum L. (common St John's wort; Hypericaceae) are sold as phytopharmaceuticals and herbal supplements to treat mild to moderate depression and as food additives. Extensively cultivated in Europe, plants can be infected by anthracnose (Colletotrichum gloeosporioides), a virulent fungal pathogen that causes tissue necrosis and dramatically decreases crop value. Such infections triggered the production of new secondary metabolites, specifically xanthones, in cell culture experiments. RESULTS: Bioassay‐guided fractionation of H. perforatum root extracts, testing for growth inhibition of plant pathogenic fungi from the genera Colletotrichum, Botrytis, Fusarium and Phomopsis, was performed. In vitro anti‐inflammatory activity through inhibition of COX‐1, COX‐2 and 5‐LOX‐catalyzed LTB₄ formation was also evaluated. Extracts were analyzed by various chromatographic means and structure elucidation was performed using data from nuclear magnetic resonance and mass spectrometry. CONCLUSION: Researchers have previously described constituents from the aerial parts of this species, but few reports describe secondary metabolites found in underground parts, of particular interest because the lower stem and upper root are often sites of fungal infection. This work resulted in the isolation of three xanthones: 1,6‐dihydroxy‐5‐methoxy‐4′,5′‐dihydro‐4′,4′,5′‐trimethylfurano‐(2′,3′:3,4)‐xanthone; 4,6‐dihydroxy‐2,3‐dimethoxyxanthone; and cis‐kielcorin, one of which possessed novel bioactivity against species of Phomopsis and inhibited 5‐LOX‐mediated LTB₄ formation. Copyright © 2010 Society of Chemical Industry