二氧化氯气体处理对果蔬采后生理代谢及质量安全的影响

二氧化氯（ClO₂）气体是国际上公认的安全、无毒绿色消毒剂,其具有杀菌性强、扩散性和穿透性好、不发生氯的替代反应、无毒副作用等优点,已在农业、食品、医药等领域应用广泛。近年来,ClO₂在果蔬保鲜领域得到很好的应用,成为研究热点。本文论述了ClO₂气体对采后果蔬中乙烯和呼吸、膜脂、苯丙烷类、能量等生理代谢及果蔬失水软化、外观和营养等贮藏品质方面的影响,并讨论了ClO₂气体对果蔬致病、致腐微生物的杀菌机理及其杀菌效果,同时分析了ClO₂气体在果蔬保鲜中的应用限制,最后,根据目前的应用研究现状对存在的问题进行总结,并对其未来的应用前景进行了展望,旨在为拓宽ClO₂气体在果蔬保鲜领域的广泛应用提供参考。     

气调包装技术在鲜切肉苁蓉保鲜中的应用

针对鲜切肉苁蓉易出现褐变和品质劣变的问题,该研究以新疆荒漠肉苁蓉为研究试材,在(4±0.5)℃条件下,采用气调包装(4%O₂+2%CO₂+94%N₂、4%O₂+4%CO₂+92%N₂、4%O₂+6%CO₂+90%N₂)进行处理,采用L^*值、ΔE、褐变度、硬度、水分含量、呼吸强度、维生素C含量、总酚含量和菌落总数等指标评价气调包装对鲜切肉苁蓉褐变及品质的影响。结果表明,气调包装处理能有效抑制鲜切肉苁蓉在贮藏过程中褐变和品质劣变,且以4%O₂+6%CO₂+90%N₂气调包装保鲜效果最佳。该处理能有效抑制贮藏期间鲜切肉苁蓉多酚氧化酶(polyphenol oxidase, PPO)、过氧化物酶(peroxidase, POD)活性(P<0.05)、延缓其褐变过程。此外,该条件可显著抑制鲜切肉苁蓉呼吸强度,...     

褪黑素在果蔬采后品质劣变中的调控作用

褪黑素是广泛存在于生物体内的一种吲哚类色胺,具有调控果蔬衰老、清除活性氧自由基、防止抗氧化酶钝化等作用。最新研究发现褪黑素可以显著延缓果蔬采后由呼吸作用、乙烯释放、蒸腾作用、自由基代谢等代谢活动导致的品质劣变。本文从果蔬采后品质劣变角度综述了褪黑素对果蔬采后生理的调节作用,从导致品质劣变的关键生理活动包括呼吸作用、乙烯合成、蒸腾作用、酶促褐变、膜脂氧化、抗性激活等方面阐述了外源褪黑素的调控机制,系统阐述了外源褪黑素对果蔬品质的影响,包括感官品质、糖酸代谢、风味变化等,以期为褪黑素在保持果蔬采后品质及相关贮藏保鲜新技术的应用奠定一定的理论基础和技术支持。     

不同包装方式对香酥虾球品质的影响

为研究不同包装方式对香酥虾球（crispy shrimp balls）贮藏过程中品质的影响,以聚乙烯尼龙（PE/PA）作为包装材料,采用普通热封包装、气调包装（100% N₂、70% N₂+30% CO₂、50% N₂+50% CO₂、30% N₂+70% CO₂、100% CO₂）和真空包装7种包装方式,测定不同贮藏时间下香酥虾球的感官评分、脂质、蛋白质和微生物指标的变化,确定香酥虾球的最佳包装方式,同时,采用电子鼻/舌和气相色谱-质谱联用技术（GC-MS）对最佳包装方式下香酥虾球贮藏过程中的风味品质变化进行研究。结果表明,在贮藏过程中,30% N₂+70% CO₂气调包装组和100% CO₂气调包装组的过氧化值、羰基价、丙二醛含量、蛋白质羰基含量和菌落总数均低于其他组,感官评分和蛋白质巯基含量则均高于其他组（P<0.05）。随着CO₂浓度增加,香酥虾球的品质劣变速率降低,但100% CO₂气调包装组在贮藏30 d后存在塌瘪现象。因此,最佳包装方式为30% N₂+70% CO₂的气调包装。在最佳包装方式下（30% N₂+70% CO₂气调包装）,香酥虾球贮藏过程中的风味成分变化明显,贮藏30 d后香酥虾球中的醇类、醛类、含氮硫类及含氧类的挥发性种类及含量总量显著（P<0.05）增加。新鲜和贮藏30 d香酥虾球的挥发性风味物质分别有39种和57种,新鲜香酥虾球中甲酸乙烯酯、环丁醇、3,4-癸二烯和3,3-二苯基-5-甲基吡唑含量较高,贮藏30 d后香酥虾球中甲酸乙烯酯、2-异氰基-环己醇（反式）、3-环己基丙醇、（E,E）-2,4-十二烷醛、柠檬醛、2-异氰基-2,4,4-三甲基戊烷和2,3-环氧丁烷含量较高。本研究表明30% N₂+70% CO₂的气调包装可以有效减缓香酥虾球的品质劣变。     

LEDs技术在果蔬杀菌保鲜领域应用研究进展

水果和蔬菜是人类饮食的重要组成部分,可为人体提供多种营养物质。然而,果蔬在采收、加工、贮藏等环节极易污染微生物,造成品质劣变,甚至引发食源性疾病。作为一种非热加工技术,发光二极管(LEDs)技术具有绿色环保、节能、寿命长等优点,在农业和食品领域具有广阔应用前景。综述LEDs技术在果蔬杀菌中应用,探讨LEDs技术的杀菌机理及影响因素,概括LEDs技术对果蔬主要品质的影响,并对该技术的发展趋势进行讨论分析。     

不同二氧化碳浓度气调包装对生鲜鸡翅贮藏过程中挥发性有机物的影响

为探究不同二氧化碳和氮气比例对生鲜鸡翅贮藏过程挥发性有机物的影响,本研究设置对照组和气调包装组（20%CO₂+80%N₂、30%CO₂+70%N₂、40%CO₂+60%N₂、100%N₂）,运用GC-IMS研究其在低温贮藏过程中挥发性有机物的变化,同时监测其感官品质、菌落总数、pH及色泽的变化规律。结果表明:对照组的菌落总数在第6 d超出国家限量标准,同时出现明显的不良气味,而20%～40%CO₂气调包装组中尚未产生腐败气味。随着包装内二氧化碳浓度的增加,气调包装对微生物的抑制作用增强。GC-IMS分析发现,对照组腐败样品中己醛、吲哚含量高于未腐败样品。贮藏6 d,对照组中己醛、2-甲基丙酸、吲哚、2-癸酮、丁酸等挥发性有机物的相对含量显著高于其他处理组（P<0.05）,且这些物质的相对浓度随着包装内二氧化碳浓度的增加而减少,因此,较高浓度的CO₂可有效抑制鸡翅腐败气味的产生,己醛、2-甲基丙酸、吲哚等有机物可能是生鲜鸡翅中腐败气味形成的主要原因。本研究可为生鲜鸡翅的保鲜技术发展和应用提供理论参考。     

响应面法优化铁皮石斛多糖纯化工艺

目的:用响应面法优化铁皮石斛粗多糖的双水相萃取纯化工艺。方法:通过单因素实验考察了(NH₄)₂SO₄质量分数、C₂H₅OH质量分数和萃取温度对多糖萃取率和除蛋白率的影响,进而进行响应面试验,以多糖萃取率和除蛋白率为响应值进行统计分析。结果:各因素对多糖萃取率和除蛋白率的影响程度由大到小依次为萃取温度 > (NH₄)₂SO₄质量分数 > C₂H₅OH质量分数。以双水相体系的总质量为基准,实验最佳萃取条件为: (NH₄)₂SO₄质量分数为18.80%、C₂H₅OH质量分数为25.00%、萃取温度为25.00 ℃,铁皮石斛多糖萃取率和除蛋白率分别为94.39%和91.36%。结论:此方法能够有效对铁皮石斛粗多糖进行纯化,为铁皮石斛多糖的开发利用提供理论依据。     

鲜切果蔬品质劣变影响因素及其可能机理

鲜切果蔬是指新鲜果蔬原料经预处理、清洗、切分、保鲜、包装和贮藏等多道工序制成的不影响其鲜活状态的一种制品。品质快速劣变是影响其货架寿命的主要原因。本文综述鲜切果蔬品质快速劣变的影响因素及其可能机理,旨在为鲜切果蔬贮藏保鲜新技术的建立和应用提供理论依据。     

正交实验优化柚皮中柚皮苷的超声辅助双水相提取工艺

采用超声辅助正丙醇/(NH₄)₂SO₄双水相萃取技术对菊花芯柚果皮中柚皮苷的提取分离工艺进行系统研究。采用单因素均分法系统考察了(NH₄)₂SO₄质量分数、正丙醇质量分数、柚皮干粉加入量、pH、温度和时间6种关键因素对柚皮苷得率的影响,通过正交实验设计确定了双水相萃取技术最优工艺条件,并进行了放大实验研究和对比实验。结果表明,柚皮苷主要富集于上相,在优水平下,构建10.0 g双水相体系,正丙醇质量分数为21%(w/w),(NH₄)₂SO₄质量分数为18%(w/w),柚皮干粉加入量为0.15 g,调节pH至4.5,40℃条件下,超声提取30 min,柚皮苷得率为4.27%,RSD为1.23%,100倍放大后柚皮苷得率达到4.25%。对比热回流提取,正丙醇/(NH₄)₂SO₄双水相提取具有提取时间短、温度低、能耗小、效果好等优点,优势明显,可以实现柚皮中柚皮苷的有效分离,为工业制备柚皮苷提供了一种新途径。     

乙烯利处理对去皮莲藕酚类和活性氧代谢的影响

目的 探究乙烯利(Ethephon,ET)处理对去皮莲藕(Nelumbo nucifera Gaertn)贮藏品质的影响及潜在机制。方法 以鄂莲5号莲藕为试验材料,每12 h测定其在20 ℃贮藏期间的色泽、酚类物质含量及其相关酶活性、活性氧(ROS)及抗氧化酶活性变化。结果 表明4.0 g/L乙烯利溶液浸泡去皮莲藕5 min有效抑制了去皮莲藕的褐变,显著延缓了L*值的下降。在整个贮藏期间,与对照相比,乙烯利处理提高了苯丙氨酸解氨酶(PAL)和多酚氧化酶(PPO)的活性,诱导总酚物质含量的增加。乙烯利处理提高了过氧化物酶(POD)、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)的活性,同时增强了1,1-二苯基-2-三硝基苯肼自由基清除率(DPPH)。乙烯利抑制超氧阴离子的产生速率(O2.-⁾,降低羟基自由基生成速率(.OH)、丙二醛(MDA)和过氧化氢(H2O2)含量。结论 综上表明,4.0 g/L乙烯利处理可以通过诱导酚类物质的生成和提高自身的抗氧化能力来延缓去皮莲藕的品质劣变,可为维持果蔬品质方面的应用提供理论参考。     

Recent advances in modified atmosphere packaging and edible coatings to maintain quality of fresh-cut fruits and vegetables

Processing of fruits and vegetables generates physiological stresses in the still living cut tissue, leading to quality deterioration and shorter shelf life as compared with fresh intact produces. Several strategies can be implemented with the aim to reduce the rate of deterioration of fresh-cut commodities. Such strategies include low temperature maintenance from harvest to retail and the application of physical and chemical treatments such as modified atmosphere packaging (MAP) with low O₂ and high CO₂ levels and antioxidant dips. Other technologies such as edible coatings with natural additives, new generation of coatings using nanotechnological solutions such as nanoparticles, nanoencapsulation, and multilayered systems, and nonconventional atmospheres such as the use of pressurized inert/noble gases and high levels of O₂ have gained a lot of interest as a possibility to extend the shelf life of minimally processed fruits and vegetables. However, the high perishability of these products challenges in many cases their marketability by not achieving sufficient shelf life to survive the distribution system, requiring the combination of treatments to assure safety and quality. This review reports the recent advances in the use of MAP, edible coatings, and the combined effect of both technologies to extend the shelf life of fresh-cut fruits and vegetables.     

Modified atmosphere packaging of fresh produce: Current status and future needs

Fresh produce is more susceptible to disease organisms because of increase in the respiration rate after harvesting. The respiration of fresh fruits and vegetables can be reduced by many preservation techniques. Modified atmosphere packaging (MAP) technology is largely used for minimally processed fruits and vegetables including fresh, “ready-to-use” vegetables. Extensive research has been done in this research area for many decades. Oxygen, CO₂, and N₂, are most often used in MAP. The recommended percentage of O₂ in a modified atmosphere for fruits and vegetables for both safety and quality falls between 1 and 5%. Although other gases such as nitrous and nitric oxides, sulphur dioxide, ethylene, chlorine, as well as ozone and propylene oxide have also been investigated, they have not been applied commercially due to safety, regulatory, and cost considerations. Successful control of both product respiration and ethylene production and perception by MAP can result in a fruit or vegetable product of high organoleptic quality; however, control of these processes is dependent on temperature control.     

Impact of Mixtures of Different Fresh‐Cut Fruits on Respiration and Ethylene Production Rates

Packaging and storage of fresh‐cut fruits and vegetables are a challenging task, since fresh produce continue to respire and senesce after harvest and processing accelerates the physiological processes. The response on respiration and ethylene production rates of fresh produce to changes in O₂ and CO₂ concentrations and temperature has been extensively studied for whole fruits but literature is limited on processed and mixed fresh‐cut fruits. This study aimed to investigate the effects of mixing various proportions of fresh‐cut fruits (melon chunks, apple slices, and pineapples cubes) on respiration and ethylene production rates and to develop predictive models for modified atmosphere packaging. The experiment was designed according to a simplex lattice method and respiration and ethylene production rates were measured at 10 °C. Results showed that single component pineapple cubes, apple slices, and melon chunks, in this order, had significant constant coefficients (P = 0.05) and the greatest impact on respiration rate while the interactive binary and tertiary coefficients were insignificant. For ethylene production rates, single component apple slices, melon chunks, and pineapple cubes, and their 3‐component mixtures, in this order, had significant constant coefficients (P = 0.05) while binary coefficients were insignificant. Mathematical models were developed and validated; the cubical model was the best to describe the influence of proportion of fruit on respiration and ethylene production rates, however, considering simplicity the linear part of the model is recommended to quantify respiration and ethylene production rates of mixed fresh‐cut fruits.     

Modified atmosphere packaging of fruits and vegetables

Modified atmospheres (MA), i.e., elevated concentrations of carbon dioxide and reduced levels of oxygen and ethylene, can be useful supplements to provide optimum temperature and relative humidity in maintaining the quality of fresh fruits and vegetables after harvest. MA benefits include reduced respiration, ethylene production, and sensitivity to ethylene; retarded softening and compositional changes; alleviation of certain physiological disorders; and reduced decay. Subjecting fresh produce to too low an oxygen concentration and/or to too high a carbon dioxide level can result in MA stress, which is manifested by accelerated deterioration. Packaging fresh produce in polymeric films can result in a commodity-generated MA. Atmosphere modification within such packages depends on film permeability, commodity respiration rate and gas diffusion characteristics, and initial free volume and atmospheric composition within the package. Temperature, relative humidity, and air movement around the package can influence the permeability of the film. Temperature also affects the metabolic activity of the commodity and consequently the rate of attaining the desired MA. All these factors must be considered in developing a mathematical model for selecting the most suitable film for each commodity.     

Recent advances in pressure modification-based preservation technologies applied to fresh fruits and vegetables

Fresh fruits and vegetables are important parts of the human diet. The consumer demand for fruits and vegetables is increasing due to their rich nutritional value, appealing taste, and healthy perception. However, due to their highly perishable nature, appropriate preservation technologies must be developed to meet the consumer’s demand for healthy, additive-free, microbiologically safe, and high quality fresh fruits and vegetables. The preservation technologies based on modification or control of pressure alters the normal atmospheric pressure of the preservation environment. The materials to be preserved are subjected to either very high or low pressure to extend their shelf life. The mechanism, advantages, and limitations of pressure modification-based preservation methods such as high hydrostatic pressure, hyperbaric treatment, vacuum cooling, hypobaric storage, and vacuum packaging focusing on their applicability to fresh fruits and vegetables have been reviewed. This review suggests that these technologies have potential to extend the shelf life and achieve a better preservation of the quality of fresh fruits and vegetables.     

An Overview on Litchi Fruit Quality and Alternative Postharvest Treatments to Replace Sulfur Dioxide Fumigation

Litchi fruit quality is determined by chemical parameters, color, fruit composition (vitamins and minerals) and aroma volatiles. Globally there are growing concerns regarding the use of “sulfiting” agents in fresh fruits and vegetables. Consequently, new restrictive U.S. Food and Drug Administration regulations require its declaration. Sulfur dioxide (SO₂), used as a fumigant for litchi, has been officially defined as a pesticide. Detectable levels must be ≤ 10 ppm as specified by the EU. Although an alternative sulfiting agent, Na₂S₂O₅ impregnated pads, showed promising control of decay and color retention, its usage is sometimes limited since the active concentration depends on the type of cultivar. This review summarises the developments in finding appropriate alternative technologies to replace SO₂ fumigation.     

The microbiology of minimally processed fresh fruits and vegetables

Minimally processed fresh (MPF) fruits and vegetables are good media for growth of microorganisms. They have been involved in outbreaks because of the consumption of products contaminated by pathogens. They are also sensitive to various spoilage microorganisms such as pectinolytic bacteria, saprophytic Gram‐negative bacteria, lactic acid bacteria, and yeasts. Contamination of MPF fruits and vegetables occurs at every stage of the food chain, from cultivation to processing. Polluted environments during cultivation or poor hygienic conditions in processing increase the risk of contamination with foodborne pathogens. Although MPF fruits and vegetables may harbor psychrotrophic microorganisms such as fluorescent pseudomonads or Listeria monocytogenes, good control of refrigeration temperature limits growth of spoilage and pathogenic microorganisms. Modified atmospheres are often efficient to maintain or improve visual and organoleptic quality of MPF fruits and vegetables, but their effects on microorganisms are inconsistent. Chemical disinfection can partially reduce the initial bacterial contamination; irradiation seems to be more efficient. The applications of legislations and quality assurance systems to control contamination, survival, and growth of foodborne pathogens in MPF fruits and vegetables are discussed.     

Role of biological control agents and physical treatments in maintaining the quality of fresh and minimally-processed fruit and vegetables

Abstract

Fruit and vegetables are an important part of human diets and provide multiple health benefits. However, due to the short shelf-life of fresh and minimally-processed fruit and vegetables, significant losses occur throughout the food distribution chain. Shelf-life extension requires preserving both the quality and safety of food products. The quality of fruit and vegetables, either fresh or fresh-cut, depends on many factors and can be determined by analytical or sensory evaluation methods. Among the various technologies used to maintain the quality and increase shelf-life of fresh and minimally-processed fruit and vegetables, biological control is a promising approach. Biological control refers to postharvest control of pathogens using microbial cultures. With respect to application of biological control for increasing the shelf-life of food, the term biopreservation is favored, although the approach is identical. The methods for screening and development of biocontrol agents differ greatly according to their intended application, but the efficacy of all current approaches following scale-up to commercial conditions is recognized as insufficient. The combination of biological and physical methods to maintain quality has the potential to overcome the limitations of current approaches. This review compares biocontrol and biopreservation approaches, alone and in combination with physical methods. The recent increase in the use of meta-omics approaches and other innovative technologies, has led to the emergence of new strategies to increase the shelf-life of fruit and vegetables, which are also discussed herein.