辐照技术在我国烟草中的应用研究进展

辐照技术是一项绿色高新技术,已经广泛应用于食品加工、化工材料等领域,并产生了巨大的经济与社会效益。辐照技术应用于烟草可以达到杀虫、防霉、加速醇化、改善吸食品质、降解有害成分等多重作用。综述了辐照技术在烟草中的应用研究现状及辐照对烟草成分的影响,介绍了烟草辐照的安全性,指出了辐照技术在烟草中应用存在的问题,对其应用前景进行了展望,提出了今后烟草辐照研究工作的重点。     

肉类保藏技术(六) 辐照技术及其在肉类食品保藏中的应用

辐照技术是一种新型的冷杀菌技术,具有无残留、无污染、高效、节能等优点,因此在食品保藏中广泛应用。辐照处理不仅能有效提高肉品的卫生安全性、延长其保质期,并可最大程度地保持肉品的原有营养价值和感官特征,因此备受人们关注。本文主要介绍了食品辐照技术的原理、优点及辐照对肉品营养成分的影响、辐照肉品的安全性、辐照技术的在肉品保藏中的应用,并对辐照技术在肉品保藏中应用的前景进行了展望。     

食品辐照技术及其在食品中的应用

食品辐照技术是一项新型的食品保藏技术,具有安全、无污染等优点。综述食品辐照技术的原理和特点,讨论辐照技术在食品的杀菌杀虫、抑制发芽、降解有毒有害物质等方面的应用,指出其在研究和应用中存在的问题,并展望其应用前景。     

辐照技术对食品安全性的影响

辐照技术在食品工业已经应用多年,但发展速度比较缓慢,其主要原因是公众缺乏对辐照食品安全性的全面了解。本文就辐照技术对食品安全性可能带来的影响加以分析,以便客观评价辐照食品的安全性,推进辐照技术在食品工业中的应用。     

辐照杀菌技术在调味香辛料中的应用进展

辐照技术是一项安全、卫生、方便、经济、有效的食品加工新技术。本文主要从食品辐照加工概述、调味香辛料微生物污染状况、辐照灭菌在调味香辛料灭菌处理中的应用及其优势等方面,介绍了辐照杀菌技术在调味品中的应用进展,并展望了辐照调味香辛料商业化前景及其发展方向。     

食品辐照技术及其食品中的应用

食品辐照技术是一项新型的食品保藏技术,具有安全性、无污染等优点,综述辐照技术的原理和特点,讨论辐照技术在食品的杀菌杀虫、抑制发芽、降解有毒有害物质等方面的应用,并指出其在研究和应用中存在的问题,并对其应用前景进行了分析。     

辐照保藏技术在肉制品中的应用

对辐照保藏技术及其在肉品中的应用、使用安全性以及辐照、保藏技术存在的问题等方面进行综述，对今后辐照技术应重点研究开发的方向进行了展望。     

辐照食品的卫生安全性研究和管理现状

为促进食品辐照技术的商业化应用，给我国食品辐照管理部门提供借鉴，综述了食品辐照的目的、经电离辐照加工后食品的变化、食品辐照加工的优势、食品辐照技术的历史回顾。介绍了美国、加拿大、欧盟等世界主要贸易国对辐照食品的管理和应用及其辐照方法的发展前景。辐照方法加工食品是一种安全、卫生、经济的新型技术。食品辐照技术既保护环境，又以很少的能量防止了粮食等食物的损失，还可保证食品的安全卫生。     

辐照在肉类制品贮藏中的应用

介绍辐照技术在肉食品贮藏中的应用，肯定了辐照肉品的卫生安全性。并就目前肉类产品辐照过程中存在的问题，结合国内外研究辐照肉品的情况，提出辐照技术对肉品微生物、肉品品质进行控制的措施。     

辐照技术在食品工业中的应用及其发展

阐述了食品辐照技术的原理、优点及其在商业化上的应用;同时对辐照技术的发展作了展望。     

Microbial Decontamination of Tea (Camellia sinensis) by Gamma Radiation

ABSTRACT:  Processed dry tea leaves are prone to microbial contamination during post-processing handling and storage. The dry tea leaves may thus carry bacteria and fungi of potential health risk to consumers. Also, during storage under high humidity, absorption of moisture may encourage fungal growth and result in caking of the product. Gamma radiation processing was tried as a method for microbial decontamination. A radiation dose of 5 kGy was found to be effective for this purpose. No significant effect was observed on total phenolics in radiation-processed tea leaves. The antioxidant and biological properties of tea such as free radical scavenging activity, inhibition of xanthine oxidase and lipid peroxidation, and superoxide and nitrite scavenging activities were not affected due to radiation treatment within a dose of 10 kGy. The antimicrobial and sensory properties were also unaffected by the radiation treatment.     

Recovery of Salmonella enterica serovars Typhimurium and Tennessee in peanut butter after electron beam exposure

The effect of electron beam (e-beam) radiation on the recovery of Salmonella serotypes Tennessee (ATCC 10722) and Typhimurium (ATCC 14028) in creamy peanut butter over a 14-d storage period at 22 °C was studied. Each Salmonella type was independently inoculated into peanut butter and subjected to e-beam doses that ranged from 0 to 3.1 kGy, confirmed by film dosimetry. After 2-, 4-, 6-, 8-, and 14-d of storage, microbial analyses were conducted. Survivors were recovered on growth and selective media using standard spread-plating methods. Microbial counts (CFU/g) were log-converted and differences were determined by ANOVA and Tukey's Honestly Significant Differences test. When samples were not e-beam-treated, there were no significant changes (P > 0.05) in microbial numbers over time. In e-beamed samples, microbial numbers decreased over time; however, reductions were not always significant. Initial recovery rates (R-rates) 2 d after e-beam treatment were significantly different for the 2 strains of Salmonella and between recovery media (P < 0.05); however, these differences did not persist for the remainder of the storage period (P > 0.05) indicating that injured cells were not able to survive in the high-fat, low-water activity peanut butter environment. R-rates for both strains of Salmonella were maintained until day 14 when there were significant reductions in Salmonella Typhimurium (P < 0.05). These results indicate that Salmonella Tennessee and Salmonella Typhimurium will survive in peanut butter when exposed to nonlethal doses of e-beam irradiation. PRACTICAL APPLICATION: Electron beam (e-beam) irradiation is an alternative to thermal processing; this technique inactivates microorganisms and insects that might be present in a food by generating radiation by accelerated electrons that inactivate organisms directly because of interaction with cell components and indirectly by producing free radicals that disrupt integrity of the cell membrane. E-beam radiation will reduce the number of probable microbiological hazards that could be present while the food remains generally unaffected in texture, taste, and nutritional value. A recent study showed e-beam irradiation to be effective at reducing both Salmonella Tennessee and Typhimurium in peanut butter by one log after exposure to less than 1 kGy, highlighting the need to explore this process further.     

Changes in quality, liking, and purchase intent of irradiated fresh-cut spinach during storage

The use of ionizing radiation to enhance microbial safety of fresh spinach at a maximum dose of 4 kGy has been approved by the U.S. Food and Drug Administration (FDA). However, whether spinach can tolerate those high doses of radiation is unclear. Therefore, this study was conducted to investigate the effects of irradiation and storage on quality, liking, and purchase intent of fresh-cut spinach. The oxygen radical absorbance capacity values and total phenolic content were not consistently affected by irradiation. However, the ascorbic acid content of irradiated sample decreased rapidly during storage, resulting in these samples being lower in ascorbic acid content than controls after 7 and 14 d of storage at 4 °C. Sensory evaluation by a 50-member panel revealed that purchase intent and ratings for liking of appearance, aroma, texture, flavor, and overall were not affected by irradiation at doses up to 2 kGy. Therefore, irradiation at doses up to 2 kGy may be used to enhance microbial safety without affecting consumer acceptance or overall antioxidant values of irradiated spinach.     

Effect of γ-irradiation on rice seed vigor assessed by near-infrared spectroscopy

High-energy radiation such as γ-ray can kill pests, insects and bacteria with high efficiency and low-cost, and so it has been utilized as one of the most promising tools for food storage. On the other hand, high-energy radiation may also induce physiological, biochemical and genetic changes of crops. In this study, near-infrared (NIR) spectroscopy as a non-destructive, fast, low-cost analytical tool was employed to investigate the effect of γ-ray irradiation on the irradiated rice seeds. The alteration of seed vigor was assessed after the rice seeds were irradiated with different irradiation doses and at different storage ages. The relationship between seedling height, seed vigor and irradiation dosage was established based on the analysis of the NIR spectral data. The accuracy of the PLS (partial least squares) prediction model was checked by parameters such as the root mean square error of prediction (RESEP) and the residual prediction deviation (RPD). Our results showed that with increase of irradiation dosage and storage age, seed injury increased resulting in reduced seed vigor and seedling height. This work thus demonstrates the successful application of NIR for the rapid and non-invasive evaluation of rice seeds after irradiation and storage.     

Electrophoretic patterns of microwaved and γ‐irradiated beef liver proteins

The effects of γ‐irradiation treatments (2.5, 5 and 10 kGy) and microwaves generated from an oven at low and defrost power settings for 0.5, 1 and 2 min on the total proteins and protein patterns of beef liver immediately after treatment and during frozen storage (?18 °C) for different periods were studied. Chemical analyses indicated that the protein content of beef liver was reduced after exposure to γ‐radiation or microwaves and also during frozen storage. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS‐PAGE) was used to illustrate the changes in protein bands of different molecular weights and their percentages before and after exposure to gamma and microwave radiation. The main effect of γ‐radiation on the protein patterns of beef liver was the disappearance of some high‐molecular‐weight protein bands and the development of other bands characterised by moderate and low molecular weights. This finding indicates the degradation of beef liver proteins by γ‐irradiation. In contrast, microwave treatment caused an increase in the levels of high‐molecular‐weight protein bands with a concomitant decrease in low‐molecular‐weight protein bands. This phenomenon demonstrates the polymerisation of low‐molecular‐weight proteins under the influence of microwaves. © 2001 Society of Chemical Industry     

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.     

Effect of Antioxidant and Conditions on Solubility of Irradiated Food Proteins in Aqueous Solutions

Food proteins were examined after irradiation. Effects of exposure, headspace gas, buffer, pH, antioxidant, total protein and type, and storage were tested. Decreases in solubility of native protein and formation of high MW polymers were observed. Destruction was greatest at low protein concentrations, high radiation dose (10 kGy) and pH 7. High protein concentration (5-10%), glucose, pH 5–6 and propyl gallate were protective. Ascorbic acid effects were concentration dependent. Nitrogen headspace effect was influenced by antioxidant and was smaller than expected. Propyl gallate plus glucose or SDS helped maintain protein solubility and size at high radiation rates. Marked declines in isoelectric pH consistent with lysine destruction were revealed.     

Effects of Electron Beam Irradiation on Physical, Textural, and Microstructural Properties of "Tommy Atkins" Mangoes (Mangifera indica L.)

This research focused on determining the dose levels suitable for electron beam irradiation of mangoes without detriment to the fruit's quality characteristics. Physicochemical, textural, respiration rates, microstructural, and sensory characteristics of “Tommy Atkins” mangoes irradiated at 1.0, 1.5, and 3.1 kGy using a 10 MeV (10 kW) linear accelerator with double‐beam fixture were determined. Fruits were stored at 12 °C and 62.7% RH for 21 d and evaluated at days 0, 5, 10, and 21. Nonirradiated mangoes served as controls. Irradiation did affect the textural characteristics of mangoes at doses higher than 1.0 kGy. Mangoes exposed to 1.5 and 3.1 kGy were softer and less stiff throughout storage. The radiation‐induced softening of the fruits may be associated with changes in the structural cell such as cracks and depressions on the surface and the breakdown of the cells and its components. Irradiation at 3.1 kGy affected the color of mangoes by the end of storage. Doses up to 1.5 kGy kept respiration rates at a normal level. Irradiation did not affect the specific gravity of mangoes, a parameter associated with fruit maturity levels. No effect of irradiation on pH, water activity, moisture content, acidity, and juiciness of mangoes was detected at the dose levels used in this study. Only fruits irradiated at 3.1 kGy were unacceptable to the sensory panelists in terms of overall quality, texture, and aroma. Electron beam irradiation of “Tommy Atkins” mangoes at 1.0 kGy is the recommended treatment to maintain the overall fruit quality attributes.     

Radiation sensitivity and postirradiation growth of foodborne pathogens on a ready-to-eat frankfurter on a roll product in the presence of modified atmosphere and antimicrobials

Intervention technologies including ionizing radiation, antimicrobials, and modified atmospheres (MA) can be used to inhibit the growth of or inactivate foodborne pathogens on complex ready-to-eat foods such as sandwiches. However, the effect of these technologies when used in combination (the hurdle concept) on the survival of foodborne pathogens is unknown. The ability of ionizing radiation to inactivate Escherichia coli O157:H7, Salmonella, Listeria monocytogenes, and Staphylococcus aureus inoculated onto a frankfurter on a roll product containing the antimicrobials sodium diacetate and potassium lactate in the presence of an MA (100% N2, 50% N2 plus 50% CO2, or 100% CO2) was investigated. The radiation resistances (D10-values) of the foodborne pathogens were 0.43 to 0.47 kGy for E. coli O157:H7, 0.61 to 0.71 kGy for Salmonella, 0.53 to 0.57 for L. monocytogenes, and 0.56 to 0.60 for S. aureus. The MA had no effect on the radiation resistance of the pathogens. During a 2-week storage period under mild temperature abuse (10 degrees C), none of the pathogens were able to proliferate on the frankfurter on a roll product, regardless of the MA used. However, application of sublethal doses of ionizing radiation resulted in increased mortality of the gram-positive pathogens L. monocytogenes and S. aureus during the storage period regardless of the MA. Although the pathogens were unable to proliferate on the frankfurter on a roll product during the storage period, application of a postpackaging intervention step was needed to actually inactivate the foodborne pathogens. Ionizing radiation used in combination with sodium diacetate and potassium lactate resulted in additional mortality of L. monocytogenes and S. aureus, independent of the MA, during the 2-week storage period.     

芦笋嫩茎采后生理和品质变化及保鲜技术

介绍了芦笋嫩茎采后的生理和品质变化以及嫩茎预冷、冷藏、人工调节气体 (CA)贮藏、自发气调 (MA)贮藏、γ 辐照处理和其他贮藏保鲜技术研究进展。