Effect of nitric oxide on reactive oxygen species and antioxidant enzymes in kiwifruit during storage

BACKGROUND: The accumulation of reactive oxygen species (ROS) in kiwifruit can cause oxidative damage during storage. Little research has been carried out on the effects of nitric oxide (NO) on oxidative damage to kiwifruit. Therefore the aim of the present study was to evaluate the ability of 0.5, 1 and 2 µmol L^?1 NO aqueous solutions to alleviate oxidative damage to kiwifruit during storage. RESULTS: The most marked effect was obtained with 1 µmol L^?1 NO solution, which significantly reduced the accumulation of malondialdehyde, superoxide and hydrogen peroxide, delayed the decrease in vitamins C and E, maintained the content of soluble solids, inhibited the activity of lipoxygenase and peroxidase and increased the activity of superoxide dismutase and catalase in kiwifruit during storage. The 0.5 µmol L^?1 NO solution was too weak to significantly affect the content of ROS and the activity of enzymes. However, treatment with 2 µmol L^?1 NO solution promoted the accumulation of ROS, decreased the activity of antioxidant enzymes and accelerated peroxidation in kiwifruit during storage. CONCLUSION By increasing the activity of antioxidant enzymes and maintaining the content of vitamins C and E, treatment with 1 µmol L^?1 NO aqueous solution could protect kiwifruit against oxidative damage caused by ROS during storage. Copyright © 2008 Society of Chemical Industry     

Effects of exogenous nitric oxide on contents of soluble sugars and related enzyme activities in 'Feicheng' peach fruit

BACKGROUND: Sugar content is one of the main characteristics related to the quality of fruit. Research confirms that nitric oxide (NO) involves a physiological process and prolongs the storage life of fruit. However, little attention has been paid to the effects of NO on sugar metabolism in fruit during storage. In this study, the effect of different concentrations (0, 10, 30 µmol L^?1) of exogenous NO treatment on sugar content and related enzyme activities in ‘Feicheng’ peach fruit was investigated during storage (0–12 days after harvest) at room temperature (25 °C). RESULTS: Results showed that the decrease of firmness and accumulation of sugar and acid:sugar ratio in peach fruit during storage were significantly inhibited by treatment with 10 µmol L^?1 NO. Treatment with 10 µmol L^?1 NO could promote fructose and glucose metabolism during the first 4 days of storage, and increase the content of sucrose and the activities of sorbitol dehydrogenase, sorbitol oxidase and sucrose phosphate synthase in peach fruit during storage. However, acid invertase activity from 8 to 12 days of storage and neutral invertase activity during the first 4 days of storage were inhibited by treatment with 10 µmol L^?1 NO. At the same time, treatment with 10 µmol L^?1 NO inhibited sucrose synthase (SS) activity in decomposition during storage and SS activity in synthesis from 8 to 12 days of storage. CONCLUSION: Treatment with 10 µmol L^?1 NO had a significant impact on content of soluble sugars and related enzyme activities in ‘Feicheng’ peach fruit during storage (0–12 days) at room temperature (25 °C). Copyright © 2011 Society of Chemical Industry     

The effects of fruit maturation,delayed storage and ethylene treatment on the incidence of low‐temperature breakdown of ‘Hayward’ kiwifruit

BACKGROUND: Low‐temperature breakdown (LTB), a disorder inducing quality loss, during and after cold storage of ‘Hayward’ kiwifruit was investigated. Harvested kiwifruits during fruit maturation or after delayed storage (DS) at 20 °C for 0, 1, 2, 3 and 4 weeks and 1 µL L^?1 ethylene treatment for 24 h were stored at ? 0.5 °C for 24 weeks and additional ripening at 20 °C for 5 days. Fruit quality indices and LTB incidence and severity were determined before and after treatments. RESULTS: Harvested fruits ripened during maturation, DS and after ethylene treatment. After storage and shelf life, fruits of all treatments were at complete ripening stage. LTB incidence of early harvested fruits was high, while that of fruits of the mid (third) and late harvests was low. Fruits of the third harvest date showed progressively increased LTB incidence with increasing duration of DS to as high as 95–100% after 4 weeks. Ethylene‐treated fruits showed a comparable increase in LTB to that corresponding to 2–3 weeks of DS. CONCLUSION: In contrast to fruit maturation, postharvest (after harvest and before storage) DS at non‐chilling temperature and ethylene treatment advanced the ripening of ‘Hayward’ kiwifruit and resulted in increased LTB incidence. Copyright © 2012 Society of Chemical Industry     

Effects of ozone and chlorine postharvest treatments on quality of fresh‐cut red bell peppers

The effects of chlorine (200 μL L^?1), ozonated water (1 μL L^?1) and gaseous ozone (0.7 μL L^?1) on physicochemical attributes and microbial quality of minimally processed red bell peppers were studied. In all the experiments, O₂ continuously decreased and CO₂ concentration increased, the pH augmented and a significant softening was observed in all the fruits. By day 14, L* values decreased in all the fruits, with the greatest changes found in the chlorinated samples (approximately 12 units). Peppers treated with the aqueous solutions showed greater changes in the quality attributes with increasing washing times and especially when chlorine was used. The exposure for three min to gaseous O₃ reduced the mesophiles, psychrotrophes and fungal populations of the fresh‐cut peppers in 2.5, 3.3 and 1.8 log units, respectively. Combined with modified atmosphere, this could be an appropriate method to maintain the quality and extend the storage period of minimally processed red bell peppers.     

Effect of Hops Beta Acids on the Survival of Unstressed‐ or Acid‐Stress‐Adapted‐Listeria Monocytogenes and on the Quality and Sensory Attributes of Commercially Cured Ham Slices

This study evaluated the antilisterial activity of hops beta acids (HBA) and their impact on the quality and sensory attributes of ham. Commercially cured ham slices were inoculated with unstressed‐ and acid‐stress‐adapted (ASA)‐L. monocytogenes (2.2 to 2.5 log CFU/cm²), followed by no dipping (control), dipping in deionized (DI) water, or dipping in a 0.11% HBA solution. This was followed by vacuum or aerobic packaging and storage (7.2 °C, 35 or 20 d). Samples were taken periodically during storage to check for pH changes and analyze the microbial populations. Color measurements were obtained by dipping noninoculated ham slices in a 0.11% HBA solution, followed by vacuum packaging and storage (4.0 °C, 42 d). Sensory evaluations were performed on ham slices treated with 0.05% to 0.23% HBA solutions, followed by vacuum packaging and storage (4.0 °C, 30 d). HBA caused immediate reductions of 1.2 to 1.5 log CFU/cm² (P < 0.05) in unstressed‐ and ASA‐L. monocytogenes populations on ham slices. During storage, the unstressed‐L. monocytogenes populations on HBA‐treated samples were 0.5 to 2.0 log CFU/cm² lower (P < 0.05) than control samples and those dipped in DI water. The lag‐phase of the unstressed‐L. monocytogenes population was extended from 3.396 to 7.125 d (control) to 7.194 to 10.920 d in the HBA‐treated samples. However, the ASA‐L. monocytogenes population showed resistance to HBA because they had a higher growth rate than control samples and had similar growth variables to DI water‐treated samples during storage. Dipping in HBA solution did not adversely affect the color or sensory attributes of the ham slices stored in vacuum packages. These results are useful for helping ready‐to‐eat meat processors develop operational procedures for applying HBA on ham slices.     

1‐MCP does not improve the shelf‐life of Chinese cabbage

Chinese cabbages cv ‘Yuki’ (Brassica campestris L ssp pekinensis (Lour) Olsson) were treated with air containing 1‐methylcyclopropene (1‐MCP) at concentrations ranging from 0 to 1 µl l^?1 for 12 h at 22°C before storage for 9 weeks at 3°C. Quality, weight loss and trimming loss were measured before treatment, and before and after storage, but were not influenced by 1‐MCP. 1‐MCP at 0.1 and 1.0 µl l^?1 elicited increased levels of respiration and ethylene production which subsided when the cabbages were placed in cold storage. Copyright © 2004 Society of Chemical Industry     

Pre‐ or post‐harvest applications of putrescine and low temperature storage affect fruit ripening and quality of ‘Angelino’ plum

BACKGROUND: Plum has a very short storage life. The role of pre‐ or post‐harvest applications of putrescine (PUT) and low temperature storage on fruit ripening and quality was investigated in plum fruit (Prunus salicina Lindl. cv. Angelino). RESULTS: Pre‐ or post‐harvest PUT treatments [(0.1, 1.0 or 2.0 mmol L^?1) + 0.01% Tween‐20 as a surfactant] delayed and suppressed the climacteric ethylene production and respiration rate irrespective of the method used to apply PUT. PUT‐treated fruit following low temperature storage (0 ± 1 °C; 90 ± 5% RH), at the ripe stage exhibited higher fruit firmness and titratable acidity (TA), while soluble solids content (SSC), levels of ascorbic acid, total carotenoids and total antioxidants were lower than in untreated fruit. Fruit both sprayed with PUT and stored in low temperature for 6 weeks, at the ripe stage showed reduced respiration rate, delayed changes in the SSC:TA ratio and levels of total carotenoids compared to post‐harvest PUT application. CONCLUSION: Pre‐harvest application of 2.0 mmol L^?1 PUT 1 week before the anticipated commercial harvest was more effective in delaying plum fruit ripening and can be used to extend the storage (0 ± 1 °C) life of plums for up to 6 weeks with minimum losses in fruit quality. Copyright © 2008 Society of Chemical Industry     

Determination of luteolin and apigenin in celery using ultrasonic-assisted extraction based on aqueous solution of ionic liquid coupled with HPLC quantification

BACKGROUND: Ionic liquids are a class of organic salts with melting points equal to or below 100 °C, and their use in sample preparation has shown its promise, for example, in alleviation of environmental pollution and improvement of selectivity and extraction of certain interesting compounds. RESULTS: Optimal conditions were obtained by using 1.0 mol L^?1 1‐butyl‐3‐methylimidazolium methylsulfate ([Bmim][MS]) aqueous solution at pH 1.0 as the extraction solvent. An ultrasonic power of 200 W was chosen to ensure complete dispersion of [Bmim][MS] into celery in 90 min and the solid:liquid ratio was 1:10. CONCLUSION: The proposed ultrasonic assistant extraction approach, based on ionic liquid aqueous solution, exhibited satisfactory results, with recovery values ranging from 72.7% to 89.5%. Under optimal conditions, compared with conventional solvent extraction amounts of luteolin and apigenin were more than doubled. Copyright © 2011 Society of Chemical Industry     

Changes in cuticle compositions and crystal structure of ‘Bingtang’ sweet orange fruits (Citrus sinensis) during storage

Changes in composition and structure of orange cuticle during storage at 4°C or 25°C for 40 days were investigated. The total epicuticular wax content of fruits increased during storage at 4°C for 30 days and then decreased as storage time prolonged to 40 days, while it increased continuously at 25°C for 40 days. The total intracuticular wax content of fruits increased to 9.70 μg cm^?2 stored at 4°C for 10 days and then decreased to 6.74 μg cm^?2 for 40 days. The total intracuticular wax content of fruits was decreased to 5.17 μg cm^?2 stored at 25°C for 10 days and then increased to 10.06 μg cm^?2 for 30 days. Fatty acids were the most abundant component of the epicuticular wax and terpenoids were restricted to the intracuticular wax. Terpenoids were restricted to the intracuticular wax, and their amounts in the fruit stored at 4°C increased continuously during the first 20 days of storage at 4°C and then decreased as storage time increased up to 40 days. Although significant changes were found in the contents of the cutin monomer, their proportions did not change significantly during storage at 4°C or 25°C. Size of wax platelets crystals wax increased during storage of fruits at 4°C up to 30 days; however, the crystals were degraded and decreased as storage prolonged to 40 days. Furthermore, the shape of the fruit cuticle surface wax crystals changed from flattened platelets to small granulelike after storage at 25°C for 20–40 days. The obtained results provide detailed information about the changes in orange cuticle occur during storage at varying temperatures, which may help in preserving the quality of citrus fruits during storage.     

Effect of storage on the bioactive compounds and antioxidant activity of quince nectar

The changes of bioactive components and antioxidant activity of quince nectar were determined during 9 months of storage at 5, 20, 30 and 40 °C. The amount of total phenolics, flavonoids and antioxidant activity was significantly declined during storage at all temperatures. Loss of L‐ascorbic acid at 5, 20, 30 and 40 °C was 32.08%, 43.69%, 65.21% and 88.82%, respectively. L‐ascorbic acid degradation was in accordance with the first‐order reaction kinetics, and activation energy was found as 43.65 kJ mol^?1. After 9 months of storage, Hydroxymethylfurfural (HMF) contents of quince nectars were 15.01, 16.64, 21.69 and 57.89 mg kg^?1 at 5, 20, 30 and 40 °C, respectively. HMF accumulation fitted a zero‐order kinetic model, and activation energy was found as 88.30 kJ mol^?1. A significant correlation was found among L‐ascorbic acid, total phenolics, flavonoids and antioxidant activity.     

Methyl jasmonate reduces chilling injury symptoms and enhances colour development of ‘Kent’ mangoes

Treatment of mango (Mangifera indica cv ‘Kent’) fruits with methyl jasmonate (MJ) vapour for 20 h at 20 °C reduced chilling injury (CI) symptoms and enhanced skin colour development. MJ at 10^?4 M was the most effective concentration for reducing CI and decay in fruits stored at 5 °C followed by 7 days at 20 °C (shelf‐life period). The use of 10^?5 M MJ enhanced yellow and red colour development of mangoes stored at 20 °C. These fruits possessed higher L*, a* and b* values than untreated fruits and those treated with 10^?4 M MJ. Ripening processes were inhibited by cold storage (5 °C) in control fruits. After cold storage and shelf‐life period, fruits treated with 10^?5 M MJ ripened normally and contained the highest total soluble solids (TSS). These fruits also maintained higher sugar and organic acid levels than fruits subjected to other treatments. We concluded that MJ treatment could be used to reduce decay and CI symptoms and also to improve colour development of mango fruits without adversely affecting quality. © 2001 Society of Chemical Industry     

Overall Quality Properties of Kiwifruit Treated by Cinnamaldehyde and Citral: Microbial,Antioxidant Capacity during Cold Storage

This work was undertaken to evaluate the microbiological characteristics and antioxidant and physiological activities in kiwifruits (Actinida deliciosa var. Qinmei) with/without cinnamaldehyde (C1) and citral (C2) fumigation treatments (5 μL/L) during 0, 3, 6, 9, and 12 d of storage at 4 °C. Essential oils (EOs) treatment lowered the total viable counts, yeast, and mold to 1.54, 2.36, and 2.05 log CFU/g, respectively. Moreover, EOs improved the antioxidant activities of kiwifruit. They enhanced phenolics and flavonoids content in fruit tissue by 49.48% at day 3 and 56.93% at day 6, respectively. In addition, ascorbic acid in treated groups had the lower losing rate. Similarly, MDA (malondialdehyde), H₂O₂ (hydrogen peroxide), and ^?O₂^– (superoxide anion) production were effectively decreased in the range of 27.27% to 54.38%. Physicochemical characteristics showed that kiwifruits from treated group maintained higher levels of flesh luminosity and firmness. EOs also decreased the levels of reducing sugar by 45.97% at day 3, and increased the content of soluble protein and hydrolyzed amino acid. Therefore, postharvest EOs treatment has positive effects on delaying senescence and enhancing antioxidant capacities in kiwifruit.     

Effect of ozone and calcium lactate treatments on browning and texture properties of fresh‐cut lettuce

The effects of three treatments, 1 mg L^?1 ozone at 18–20 °C, 15 g L^?1 calcium lactate (CLac) at 50 °C and a combination thereof, were compared on fresh‐cut lettuce over 10 days of refrigerated storage. Respiration rate, browning and texture were examined as main quality indicators. The use of ozone produced a significantly (P < 0.05) higher oxygen decline than the use of CLac (from day 3 to day 10). At the end of storage, CLac (alone or combined with ozone) samples had higher oxygen content (～9%) than ozone samples (～6%). Enzymatic activity decreased significantly (P < 0.05) in ozone samples. Polyphenol oxidase activity in fresh‐cut lettuce treated with ozone (alone or combined with CLac) showed lower values on day 1 (<2500 units g^?1) and at the end of storage (<3000 units g^?1) than CLac samples (4000–4800 units g^?1). Ozone also reduced peroxidase activity to ～300 units g^?1 after treatment. Finally, pectin methylesterase activity was also reduced with ozone, showing a negative effect on textural properties. Data suggested that CLac maintained quality markers better than treatments with ozone and ozone/CLac combination over 10 days of storage. Copyright © 2006 Society of Chemical Industry     

A comparative study of composition and postharvest performance of organically and conventionally grown kiwifruits

Postharvest performance of organic and conventional ‘Hayward’ kiwifruits grown on the same farm in Marysville, California, and harvested at the same maturity stage were compared in this study. Quality parameters monitored included morphological (shape index) and physical (peel characteristics) attributes of the initial samples. Maturity indices (CO₂ and C₂H₄ production, firmness, color, soluble solids content and acidity) and content of compounds associated with flavor and nutritional quality (minerals, sugars and organic acids, ascorbic acid, total phenolics, and antioxidant activity) were determined at 0, 35, 72, 90 and 120 days of storage at 0°C, and after 1 week of shelf‐life simulation at 20°C, after each storage duration. Organically and conventionally grown kiwifruits had similar soluble solids content at harvest, but conventional kiwifruits had a higher firmness and L* value, and a lower hue angle and chromaticity, resulting in a lighter green color when compared with the organic kiwifruits. These differences were maintained for all the storage durations, with the soluble solids content increasing more in conventionally grown kiwifruits. The two production systems resulted in different morphological attributes since organic kiwifruits exhibited a larger total and columella area, smaller flesh area, more spherical shape, and thicker skin compared to conventional kiwifruits. All the main mineral constituents were more concentrated in organic kiwifruits, which also had higher levels of ascorbic acid and total phenol content, resulting in a higher antioxidant activity. Sugars and organic acids composition was not affected by the production system. Copyright © 2007 Society of Chemical Industry     

Postmortem Changes of Cultivated Atlantic Salmon and Their Effects on Salt Uptake

Rigor mortis of cultivated Atlantic salmon (Salmo salar) began to set in 8h after death and was fully resolved 60–70h after death during storage at 0°C. Maximum muscle contraction was observed 24–30h after death. ATP content decreased from 7.25 to 0.14 to 0.09 μmol/g fish from pre-rigor mortis to in-rigor mortis to post-rigor mortis state. The inosine and hypoxanthine contents increased from 0 to 1.20 to 4.06 μmol/ g fish and from 0.08 to 0.33 to 0.84 μmol/g fish during 60h storage, respectively, during 60h of storage at 0°C. Postmortem changes affected salt uptake. The equilibrium salt concentrations of pre-rigor, in-rigor and post-rigor mortis salmon were 0.53, 0.66 and 0.75 g/g salt-free solids, respectively, in a 20% (w/v) sodium chloride solution at 10°C.     

The Effects of Ultrasound Treatment and Nano-zinc Oxide Coating on the Physiological Activities of Fresh-Cut Kiwifruit

This study evaluated the efficacy of ultrasound treatment and nano-zinc oxide (ZnO) coating individually and in combination in preserving the quality of fresh-cut kiwifruit. The nano-ZnO coating solution was prepared by mixing the ZnO nanoparticles in premixed chitosan–acetic acid solution. The fresh-cut kiwifruit were dipped in NaClO solution (50 μL?L^?1 sodium, control), subjected to ultrasound treatment (40 KHz, 350 W, 10 min), or coated with nano-ZnO solution. The fresh-cut kiwifruit samples were also subjected to combined ultrasound treatment and nano-ZnO coating. All of these test samples were stored at 4 °C for 10 days. The effects of these treatments on the quality parameters such as the production of carbon dioxide and ethylene, mass loss, and flesh firmness were investigated. At the end of storage, the combination treatments with ultrasound treatment at 40 KHz with 1.2 g?L^?1 nano-ZnO coating showed lower production of ethylene (1.86 μL?kg^?1?h^?1) and carbon dioxide (10.01 mg?kg^?1?h^?1), water loss (0.46 %), and texture (7.87 N). Hence, it was concluded that the combination of ultrasound treatment with nano-ZnO coating is a promising approach to extend the shelf-life of fresh-cut kiwifruit.     

A simple pretreatment with low O2 to alleviate superficial scald in Granny Smith apples

Sealing Granny Smith apples in a low‐O₂ atmosphere for 7 days at 20 °C (LO₂‐20C) prior to cold storage reduced superficial scald development after 6 and 8 months at 0 °C plus 10 days at 20 °C. This LO₂‐20C treatment reduced the O₂ levels that induce endogenous production of significant amounts of CO₂, acetaldehyde and ethanol, and thereby reduced ethylene production in cold storage, which in turn reduced scald development. Treatment with ethanol vapour (20 mL L^?1) for 1 day at 20 °C plus 6 days at 1 °C or with low O₂ for 1 day at 20 °C plus 6 days at 1 °C (LO₂‐1C) did not reduce scald effectively. 1‐Methylcyclopropene (1‐MCP) treatment at 0.5 µL L^?1 was the most efficient at reducing scald development. In all treatments, superficial scald development proceeded from the distal blossom end towards the proximal stem end of fruits. After 6 months of cold storage at 0 °C, peel browning and membrane leakage, measured as electrical conductivity in situ, were greater at the blossom end than at the stem end of control, ethanol‐ and LO₂‐1C‐pretreated fruits. In LO₂‐20C‐ and 1‐MCP‐pretreated fruits, colour indices (hue angle, lightness and chroma) and electrolyte leakage were similar at both the stem and blossom ends and were associated with less scald development after 6 months at 0 °C. The reduction in scald development was also associated with lower peroxidase and polyphenol oxidase activities in the peel of LO₂‐20C‐ and 1‐MCP‐pretreated fruits. A simple treatment at 20 °C (LO₂‐20C) prior to regular cold storage could also be suitable for organically grown apples that cannot be treated with diphenylamine or 1‐MCP. Copyright © 2007 Society of Chemical Industry     

A Cassava Starch–Chitosan Edible Coating Enriched with <Emphasis Type="Italic">Lippia sidoides</Emphasis> Cham. Essential Oil and Pomegranate Peel Extract for Preservation of Italian Tomatoes (<Emphasis Type="Italic">Lycopersicon esculentum</Emphasis> Mill.) Stored at Room Temperature

The effect of edible cassava starch–chitosan coatings incorporated with rosemary pepper (Lippia sidoides Cham.) essential oil and pomegranate peel extract on the shelf-life of tomatoes during storage at 25 °C for 12 days was investigated. Sixteen formulations, containing 10 g L^?1 cassava starch and various concentrations of chitosan (5, 10, 20, 30 g L^?1), essential oil (0, 2.5, 5, 10 mL L^?1) and pomegranate peel extract (0, 5, 10, 20 mL L^?1) were prepared and applied to tomatoes. Physical–chemical and microbiological analyses were performed on days 1, 4, 8 and 12. Most of the coatings delayed the ripening of tomatoes, lowering the total soluble solids (38?44 g sucrose kg^?1) and weight loss (93?128 g kg^?1) and maintaining constant firmness compared to the uncoated tomatoes (45 g sucrose kg^?1, 175 g kg^?1) at 12 days of storage. Conversely, except red intensity (a*), which was higher for the uncoated samples, the colour parameters (L*, b*) of the coated and control tomatoes were similar at the end of storage. Uncoated and coated tomatoes showed no contamination during storage. The coatings showed potential to maintain the quality of tomatoes during storage at 25 °C for 12 days. In this context, tomatoes coated with the formulation comprising 10 g L^?1 cassava starch, 10 g L^?1 chitosan, 10 mL L^?1 essential oil and 20 mL L^?1 pomegranate peel extract showed the lowest weight loss and reduced total soluble solids content compared with uncoated ones.     

Ultrasound‐assisted extraction of ginsenosides in supercritical CO2 reverse microemulsions

Ultrasound‐assisted extraction of ginsenosides from ginseng in supercritical CO₂ reverse microemulsions formed by bis(2‐ethylhexyl) sodium sulfosuccinate (AOT) was studied. Prior to extraction the ginseng was soaked in water for 12 h. It was found that ultrasound significantly enhanced supercritical CO₂ reverse microemulsion extraction. The ginsenoside extraction yield from supercritical CO₂ reverse microemulsion with ultrasound of 20 kHz, 15.2 W cm^?2 and 3/6 s was 2.63 times that without ultrasound at 24 MPa extraction pressure, 45 °C extraction temperature, 4 h extraction time, 5 MPa separation pressure, 55 °C separation temperature and 2 L h^?1 CO₂ flow rate with 140 mL of 0.07 mol L^?1 AOT/ethanol. The maximum extraction yields of ginsenosides from different concentrations of reverse microemulsions were obtained at different ultrasonic intensities. The extraction yield with 20 kHz ultrasound was higher than that with 38 kHz ultrasound at suitably low intensity; however, it was lower at high intensity. The yield improvement may be basically attributed to the mechanical and thermal effects of ultrasound. Copyright © 2006 Society of Chemical Industry     

Fate of aflatoxin B(1) in contaminated corn gluten during acid hydrolysis

BACKGROUND: Aflatoxins are a group of mycotoxins that cause serious chronic disease outbreaks and contaminate several food products such as corn and its by‐product, corn gluten. The aim of the current study was to evaluate the effect of hydrochloric acid (HCl) on aflatoxin B₁ (AFB₁) degradation in contaminated corn gluten under different HCl concentrations, hydrolysis temperatures and hydrolysis times. RESULTS: During the wet milling process the highest AFB₁ level (45.68 µg kg^?1) (37.86%) was found in corn gluten fraction. Treatment with 1 mol L^?1 HCL at 110 °C resulted in degradation of AFB₁ by 27.6% (33.07 µg kg^?1) after 4 h and reached 42.5% (26.26 µg kg^?1) after 8 h. Increasing HCl concentration from 1 to 3 mol L^?1 HCl resulted in increased degradation of AFB₁, while complete degradation occurred in the presence of 5 mol L^?1 HCl after 4 h at 110 °C. Meanwhile, half‐life time of AFB₁ was recorded after 2 h at 100 °C and was < 2 h at 110 °C in the presence of 3 mol L^?1 HCl. CONCLUSION: It could be demonstrated that the manufacture of hydrolyzed vegetable protein is a suitable method for decontamination of aflatoxin in highly contaminated grains, especially gluten fractions. The hydrolysis reaction could be considered in terms of first‐order reaction kinetics of AFB₁ degradation. Copyright © 2010 Society of Chemical Industry