Shelf Life of Leafy Vegetables Treated with Natural Essential Oils

ABSTRACT: Essential oils as natural sanitizing agents were sprayed on Swiss chard leaves produced by organic methods. Samples were stored at 0 and 5°C and 97% to 98% relative humidity. Microbial populations, peroxidase activity, and sensory attributes were monitored during storage. No significant differences were observed between treated and control samples stored at 0°C. However, samples treated with the essential oils of eucalyptus, tea tree, and clove and stored at 5°C presented microbial counts significantly lower than those of control samples. The essential oils of eucalyptus, tea tree, lemon, rosemary, and clove presented peroxidase activity inhibition that, in the case of eucalyptus, increased to 65% during storage. Although some of the essential oils did appear to reduce microbial counts and peroxidase activity compared with controls, they were not effective in extending the shelflife of the Swiss chard leaves from a sensory point of view.     

抗菌材料在食品包装中的研究进展

食品抗菌包装可以有效抑制被包装食品所处环境中微生物的生长,延长食品的货架期,保证食品品质,在食品领域的地位越发重要。本文阐述了抗菌材料作用机理,介绍了常用的有机抗菌剂、无机抗菌剂和天然抗菌剂,并对食品抗菌包装的5 种实现方式进行了比较。对国内外近年来抗菌材料的研究进展,特别是对天然抗菌剂的应用做了详细说明。最后,结合目前抗菌包装膜和抗菌纸的生产现状,对食品抗菌包装的未来发展趋势和研究重点进行展望。     

Antimicrobial nanoparticles and biodegradable polymer composites for active food packaging applications

The food industry faces numerous challenges to assure provision of tasty and convenient food that possesses extended shelf life and shows long-term high-quality preservation. Research and development of antimicrobial materials for food applications have provided active antibacterial packaging technologies that are able to meet these challenges. Furthermore, consumers expect and demand sustainable packaging materials that would reduce environmental problems associated with plastic waste. In this review, we discuss antimicrobial composite materials for active food packaging applications that combine highly efficient antibacterial nanoparticles (i.e., metal, metal oxide, mesoporous silica and graphene-based nanomaterials) with biodegradable and environmentally friendly green polymers (i.e., gelatin, alginate, cellulose, and chitosan) obtained from plants, bacteria, and animals. In addition, innovative syntheses and processing techniques used to obtain active and safe packaging are showcased. Implementation of such green active packaging can significantly reduce the risk of foodborne pathogen outbreaks, improve food safety and quality, and minimize product losses, while reducing waste and maintaining sustainability.     

芳香植物精油对食品常见腐败微生物抗菌活性的研究

通过测定抑菌圈直径大小了解食品常见腐败微生物对12种芳香植物精油的抗菌敏感性,进一步测定最低抑菌浓度、最小杀菌浓度分析食用芳香植物精油抗菌活性。试验表明:食品常见腐败微生物对植物精油表现出不同的敏感性,特别是枯草芽孢杆菌对植物精油抗菌敏感性最强;综合抗菌活性最好的是牛至和百里香精油,浓度达到250μL/L时表现出广谱抗菌性,但肉桂精油对真菌有更好的抗菌活性;采用棋盘稀释法进一步研究植物精油间协同增效效果,发现牛至-百里香复配表现出显著的相加效果;气-质联用仪分析了牛至、百里香和肉桂精油的主要抗菌成分香芹酚、百里香酚和反式肉桂醛等的含量。研究可为食用植物精油作为"高效、安全"的防腐保鲜剂应用于食品领域提供了理论依据。     

Antimicrobial Wine Formulations Active Against the Foodborne Pathogens Escherichia coli O157: H7 and Salmonella enterica

ABSTRACT:  We developed wine formulations containing plant essential oils and oil compounds effective against foodborne pathogenic bacteria Escherichia coli O157:H7 and Salmonella enterica. HPLC was used to determine maximum solubility of antimicrobials in wines as well as amounts of antimicrobials extracted by wines from commercial oregano and thyme leaves. Activity of essential oils (cinnamon, lemongrass, oregano, and thyme) and oil compounds (carvacrol, cinnamaldehyde, citral, and thymol) in wines were evaluated in terms of the percentage of the sample that resulted in a 50% decrease in the number of bacteria (BA₅₀). The ranges of activities in wines (30 min BA₅₀ values) against S. enterica/E. coli were carvacrol, 0.0059 to 0.010/0.011 to 0.021; oregano oils, 0.0079 to 0.014/0.022 to 0.031; cinnamaldehyde, 0.030 to 0.051/0.098 to 0.13; citral, 0.033 to 0.038/0.060 to 0.070; lemongrass oil, 0.053 to 0.066/0.059 to 0.071; cinnamon oil 0.038 to 0.057/0.066 to 0.098; thymol, 0.0086 to 0.010/0.016 to 0.022; and thyme oil, 0.0097 to 0.011/0.033 to 0.039. Detailed studies with carvacrol, the main component of oregano oil, showed that antibacterial activity was greater against S. enterica than against E. coli and that wine formulations exhibited high activities at low concentrations of added antimicrobials. The results suggest that wines containing essential oils/oil compounds, added or extracted from oregano or thyme leaves, could be used to reduce pathogens in food and other environments.     

噬菌体在控制肉源致病菌中的应用研究进展

近年来,随着肉制品种类的不断增加和肉制品加工工艺的更新优化,食源性致病菌在肉类加工各个环节中存在的污染风险也在不断增加.如何采取有效的食源性致病菌防控措施是肉类研究领域和肉类工业关注的焦点.噬菌体作为一种可替代传统抑菌剂的生物抑菌物质,受到学者们的广泛关注,但是其在肉类工业中的应用未得到较全面地总结和评估.因此,本文概...     

Enhancing Safety and Aroma Appealing of Fresh-Cut Fruits and Vegetables Using the Antimicrobial and Aromatic Power of Essential Oils

ABSTRACT:  Microbial and aroma attributes are within the most decisive factors limiting safety and sensory appealing of fresh-cut fruits and vegetables. Alternatively, several plant essential oils (EOs) are constituted of several volatile active compounds and most of them present antimicrobial potential and had different aroma profile. Considering these premises, this hypothesis article states that safety and aroma appealing of fresh-cut produce could be improved with EO treatment. EOs could prevent fresh-cut fruit decay; however, their volatile constituents could be sorbed by the produce, and according to the aroma notes of the antimicrobial oil, sensorial appealing of odor, and flavor of the treated produce might be affected positively or negatively. Specifically, garlic oil is a natural antimicrobial constituted by sulfur compounds, which are responsible for its odor and antimicrobial properties. Besides, fresh-cut tomato is a highly perishable product that needs antimicrobial agents to preserve its quality and safety for a longer period of time. From the sensorial point of view, aroma combination of garlic and tomato is a common seasoning practice in Europe and America and well accepted by consumers. Once the right combination of flavors between the EOs and the fresh-cut produce has been selected, safety and quality of the treated fruit could be improved by adding antimicrobial protection and extra aroma. Therefore, other combinations between EOs and fresh-cut produce are discussed. This approximation could reinforce the trends of natural food preservation, accomplishing the demands of the increasing sector of consumers demanding tasty and convenient fresh-cut produce, containing only natural ingredients.     

Controlling Listeria monocytogenes and Leuconostoc mesenteroides in Uncured Deli‐style Turkey Breast Using a Clean Label Antimicrobial

Interest in natural/organic meat products has resulted in the need to validate the effectiveness of clean label antimicrobials to increase safety and shelf life of these products. A Response Surface Methodology (RSM) was used to investigate the effects of varying levels of moisture, pH, and a commercial “clean‐label” antimicrobial (cultured sugar‐vinegar blend; CSVB) on the growth rate of Listeria monocytogenes and Leuconostoc mesenteroides in uncured turkey stored at 4 °C for 16 wk. Twenty treatment combinations of moisture (60% to 80%), pH (5.8 to 6.4), and CSVB (2.5% to 5.0%) were evaluated during phase I to develop growth curves for both microbe types, whereas the interactive effects of pH (5.8 to 6.4) and CSVB (0.0 to 4.75) were tested in 16 treatment combinations during Phase II at a single moisture level using L. monocytogenes only. CSVB inhibited L. monocytogenes growth in 14 of the 20 treatments tested in Phase I and in 12 of the 16 treatments in Phase II through 16 and 8 wk, respectively. In contrast, CSVB had little effect on L. mesenteroides, with growth inhibited in only 4 of 20 treatments in Phase I and was therefore not tested further in Phase II. Significant interactions of the RSM design coefficients yielded a predictive model for L. mesenteroides growth rate, but due to lack of growth, no growth rate model was developed for L. monocytogenes. CSVB was found to be an effective antilisteral antimicrobial, while having little effect on a spoilage microorganism.     

植物精油微胶囊的制备及在食品保鲜中的应用

将植物精油制备为植物精油微胶囊,可以有效克服植物精油气味强烈、容易挥发和氧化的缺点,提高植物精油的稳定性,并且通过控制植物精油的释放速度,能使其更好发挥抑菌和抗氧化的生物活性,有利于植物精油在食品保鲜中的应用.该文介绍离子凝胶法、凝聚法、喷雾干燥法及Pickering乳液模板法这4种制备植物精油微胶囊的方法,并综述植物...     

Culture‐Independent Rapid Detection Methods for Bacterial Pathogens and Toxins in Food Matrices

Rapid detection of bacterial pathogens and toxins in foods is necessary to provide real‐time results to mitigate foodborne illness outbreaks. Cultural enrichment methods, although the most widely used, are time‐consuming and therefore inadequate for rapid pathogen detection from food samples. The development of novel “rapid” detection methods has decreased detection time dramatically. This review presents an overview of detection methods for various foodborne pathogens, including Listeria monocytogenes, Salmonella enterica, and shiga toxin‐producing Escherichia coli, and bacterial toxins in food matrices, with emphasis on those methods which do not require cultural enrichment. Discussed methods include nucleic acid‐, immunological‐, and biosensor‐based techniques. A summary of each type of detection method is given, including referenced methods from the literature. Since these discussed methods do not require cultural enrichment, there is a higher probability of interference from the food matrices. Therefore, the review also discusses the potential interference of food components on detection methods and addresses preprocessing strategies to overcome matrix associated inhibition and to concentrate low quantities of pathogens and toxins in food. Development of rapid and sensitive detection technologies advances and ensures public health safety and security.     

天然抗菌物质在食品包装中的应用研究进展

天然抗菌物质具有无毒性的特点,有良好的抗菌性,且具有广泛的来源:动物、植物和微生物等。将其应用在食品包装材料中,可延长食品货架期,同时减少防腐剂的使用,因而天然抗菌物质在食品包装行业得到广泛应用,尤其在涂料、复合膜和水凝胶方面。本文简要介绍了天然抗菌物质的种类及其性质,重点阐述了多种天然抗菌物质在食品包装行业近期的应用研究进展,为今后天然抗菌物质在食品包装中的应用提供一定参考。     

天然抗菌物在食品防腐中的应用

介绍了天然抗菌物的各种来源及其在食品防腐中的应用现状与应用潜力。     

冷冻食品货架期研究现状及发展趋势

食品货架期作为反应食品品质及安全性的标识,对它进行研究具有现实意义。文章对冷冻食品货架期进行了全面介绍,并说明了温度对冷冻食品货架期及品质的重要影响。由于冷冻食品的特殊性及冷链物流中存在的问题,在波动温度下对冻品货架期做出预测已成为研究的焦点。本文通过对冷冻食品货架期研究中的3 个重要阶段及目前研究重点的阐述,指出了未来冷冻食品货架期研究的创新点与发展方向。     

Effect of thyme oil on the preservation of vacuum-packaged chicken liver

Abstract: In this study fresh chicken liver meat was stored under vacuum packaging (VP) and under refrigeration (4 °C). The following treatments were used: V (control samples, stored under VP), VT1 (thyme oil; 0.1% v/w, stored under VP) and VT2 (thyme oil; 0.3% v/w, stored under VP). Lipid oxidation was low, as judged by determination of malondialdehyde (MDA) values, in vacuum‐packaged chicken liver meat, both in the absence or presence of thyme essential oil (EO) during the entire storage period. Of the color parameters (L*, a*, b*) monitored during storage time, L* (lightness) values for vacuum‐packaged chicken liver, irrespective of treatment, showed a varying trend, whereas a* (redness) values for V, VT1, and VT2 liver samples decreased, showing no significant differences. As determined by sensory analysis the observed shelf life of chicken liver samples was longest for VT2 (>12 d) followed by VT1 (12 d) and control (V) samples (7 d). Our results suggest that a Brochothrix thermosphact count (7 log CFU/g) and appearance of visible colonies can be used as indicators of chicken liver spoilage.     

A Comparative Study of Natural Antimicrobial Delivery Systems for Microbial Safety and Quality of Fresh‐Cut Lettuce

Nanoencapsulation can provide a means to effectively deliver antimicrobial compounds and enhance the safety of fresh produce. However, to date there are no studies which directly compares how different nanoencapsulation systems affect fresh produce safety and quality. This study compared the effects on quality and safety of fresh‐cut lettuce treated with free and nanoencapsulated natural antimicrobial, cinnamon bark extract (CBE). A challenge study compared antimicrobial efficacy of 3 different nanoencapsulated CBE systems. The most effective antimicrobial treatment against Listeria monocytogenes was chitosan‐co‐poly‐N‐isopropylacrylamide (chitosan‐PNIPAAM) encapsulated CBE, with a reduction on bacterial load up to 2 log₁₀ CFU/g (P < 0.05) compared to the other encapsulation systems when fresh‐cut lettuce was stored at 5 °C and 10 °C for 15 d. Subsequently, chitosan‐PNIPAAM‐CBE nanoparticles (20, 40, and 80 mg/mL) were compared to a control and free CBE (400, 800, and 1600 μg/mL) for its effects on fresh‐cut lettuce quality over 15 d at 5 °C. By the 10th day, the most effective antimicrobial concentration was 80 mg/mL for chitosan‐PNIPAAM‐CBE, up to 2 log₁₀ CFU/g reduction (P < 0.05), compared with the other treatments. There was no significant difference between control and treated samples up to day 10 for the quality attributes evaluated. Chitosan‐PNIPAAM‐CBE nanoparticles effectively inhibited spoilage microorganisms’ growth and extended fresh‐cut lettuce shelf‐life. Overall, nanoencapsulation provided a method to effectively deliver essential oil and enhanced produce safety, while creating little to no detrimental quality changes on the fresh‐cut lettuce.     

天然香辛料对叫化鸡中腐败细菌的抑制作用研究

研究肉类加工常用香辛料对叫化鸡产品中典型腐败菌的生长抑制效果。选择13种香辛料,通过平板孔阱法研究香辛料提取物对变质叫化鸡中分离所得的腐败菌的抑制作用,并考察加热处理对抑菌作用稳定性的影响,结果显示香辛料提取物具有广谱且稳定的抑菌作用,原料鸡经香辛料腌制处理后加工的叫化鸡产品在储藏期间菌落总数显著低于未经香辛料腌制的对照组。     

食品加工过程中致病菌控制的关键科学问题

致病性细菌是导致食源性疾病暴发的罪魁祸首,也是我国建立食品质量安全控制体系必须面对的重要危害.在食品加工过程中,食源性致病菌由于能够形成菌膜,进行亚致死损伤修复,调节抗性基因的表达等,从而对加工过程中的高温、高压、冷冻、脱水、光照、真空以及氧化等环境胁迫产生耐受性.此外,致病菌也能够分泌各种胞外毒力因子等,给食品安全带来极大的威胁.本文针对近年来食品加工过程中致病菌安全控制关键科学问题的研究进展进行阐述,并对未来的发展方向作展望.     

食品加工业中极具应用潜力的真空冷却技术

真空冷却是在真空下水分快速蒸发的预冷技术 ,可用于食品尤其适于叶类蔬菜的冷却。本文介绍了真空冷却技术的原理、在食品加工中的优缺点及其在水果、蔬菜、肉制品、鱼制品、调味品和焙烤食品中的应用     

Natural essential oils as reducing agents of peroxidase activity in leafy vegetables

The effectiveness of natural essential oils eucalyptus (Eucalyptus globulus), tea tree (Melaleuca alternifolia), melisa (Melissa officinalis), roomer (Rosmarinus officinalis), clove (Syzygium aromaticum) and lemon (Citrus limonum) to reduce peroxidase activity of organic leafy vegetables extracts was evaluated. Three oil concentrations at the minimum inhibitory concentration (MIC, 2×MIC and 4×MIC) of each natural essential oils were used. Crude vegetable extracts of Swiss chard, spinach, lettuce, butter lettuce and cabbage were the source of peroxidase activity. The effectiveness of the essential oils as natural antioxidants varied with the enzyme sources. At the MIC, clove, rosemary, lemon, melisa and tea tree had the high antioxidant properties being clove more effective than the other oils.     

乳酸链球菌素用于虾肉糜保鲜的研究

乳酸链球菌素是某些乳链球菌产生的一种多肽,对引起食品腐败的大多数革兰氏阳性菌有很好的抑制作用,是一种高效、无毒副作用的天然食品防腐剂.本文研究了乳酸链球菌素对虾肉糜保鲜的作用效果.结果显示,乳酸链球菌素能够有效地抑制虾肉糜中TVC、PC以及TVB-N值的上升;将乳酸链球菌素与山梨酸钾联合使用,保鲜效果更明显;试验结果还表明,保鲜剂的添加对虾肉糜的感官几乎没有影响.