Optimizing the use of garlic oil as antimicrobial agent on fresh-cut tomato through a controlled release system

Encapsulation of garlic oil (GO) in β-cyclodextrin (β-CD) was undertaken to generate a release system of antimicrobial volatiles and tested on microbial growth and sensory quality of fresh-cut tomato. GO volatile profile was characterized by gas chromatography mass spectrometry and to demonstrate the disadvantages of applying free GO to fresh-cut tomato, the effect of different free oil treatments (0, 50, 100, and 200 μg/100 g) on microbial growth and sensorial quality was tested. The effect of GO capsules (0, 0.25, 0.5, and 1 g/100 g) on microbial growth and sensory quality of tomato was also investigated. Allyl disulfide was the most abundant GO compound identified. The release of volatiles from GO: β-CD capsules (12: 88 [w/w] ratio) was evaluated at 100% relative humidity (RH). Close to 70% of GO volatiles were released from capsules when exposed to 100% RH during 5 wk. The most effective antimicrobial concentrations of free oil (100 and 200 μg/100 g) applied to tomatoes did not present acceptable sensory quality for panelists. Tomato was affected by the highest concentration of GO capsules applied, showing the lowest microbial growth and the highest sensory quality. In this context, successful encapsulation in β-CD could stimulate further interest in the use of GO for the control of microbial growth in fresh-cut tomato. PRACTICAL APPLICATION: The present study demonstrated that relative humidity in-package of fresh-cut tomatoes can be used as a trigger to release antimicrobial garlic oil volatiles from β-cyclodextrin capsules, reducing microbial growth and the sensory effect of the treatment caused by the free garlic oil. In this context, successful encapsulation in β-cyclodextrin could stimulate further interest in the use of garlic oil for the control of microbial growth in fresh-cut tomatoes.     

Edible alginate-based coating as carrier of antimicrobials to improve shelf-life and safety of fresh-cut melon

The effect of malic acid and essential oils (EOs) of cinnamon, palmarosa and lemongrass and their main active compounds as natural antimicrobial substances incorporated into an alginate-based edible coating on the shelf-life and safety of fresh-cut "Piel de Sapo" melon (Cucumis melo L.) was investigated. Melon pieces (50 g) were coated with alginate-based edible coating containing malic acid (EC) and EOs or their active compounds before to be packed in air filled polypropylene trays and stored at 5 degrees C for shelf-life and sensory studies. On the other hand, melon pieces were inoculated with a Salmonella Enteritidis (10(8) CFU/ml) culture before applying the coatings containing malic acid and EOs or their active compounds to safety study. Controls of fresh-cut melon non-coated or coated with EC without EOs were also prepared. EC was effective to improve shelf-life of fresh-cut melon from microbiological (up to 9.6 days) and physicochemical (>14 days) points of view in comparison with non-coated fresh-cut melon, where microbiological and physicochemical shelf-life was up to 3.6 days and lower than 14 days, respectively. In addition, the incorporation of EOs or their active compounds into the edible coating prolonged the microbiological shelf-life by more than 21 days in some cases due probably to an enhanced antimicrobial effect of malic acid+EOs; however, some fresh-cut melon characteristics were affected such as firmness and color causing a reduction of physicochemical shelf-life. Significant reductions (p<0.05) of S. Enteritidis population in inoculated coated fresh-cut melon were achieved, varying the effectiveness of the coatings depending on the EOs or the active compound and their concentrations. According to the results, palmarosa oil incorporated at 0.3% into the coating appear to be a promising preservation alternative for fresh-cut melon, since it had a good acceptation by panellists, maintained the fruit quality parameters, inhibited the native flora growth and reduced S. Enteritidis population.     

Bio-preservation of fresh-cut tomatoes using natural antimicrobials

Effects of several natural volatile compounds such as methyl jasmonate (MJ), ethanol (ETOH), their combination (MJ–ETOH), tea tree oil (TTO) and garlic oil (GO) were evaluated on fresh-cut tomato storage at 5 °C for 15 days. Microbial growth, in-packaged atmosphere, quality attributes (firmness and color) and bioactive compounds (lycopene content, ascorbic acid and phenolic compounds) of fresh-cut tomatoes were determined. The shelf-life based on microbial growth was longer on fresh-cut tomatoes treated with natural volatile compounds than in control fresh-cut tomatoes. Treatment with ETOH combined with MJ was more effective in suppressing microbial proliferation than the individual treatments with each natural volatile compound. The lowest in-packaged atmosphere modification was detected in fresh-cut tomatoes treated by ETOH. In addition, this treatment better maintained firmness and color attributes than those treated with the other antimicrobial compounds. Related to the bioactive compounds, the use of MJ let keep higher content of lycopene, ascorbic acid and phenolic compounds than the other treatments. Thus, the shelf-life of fresh-cut tomatoes could be prolonged by the use of natural antimicrobials, which do not have significant negative effects on health-related compounds.     

Investigation of the volatile aroma components of garlic leaves essential oil. Possibility of utilization to enrich garlic bulb oil

The volatile aroma components of Egyptian green garlic leaves essential oil was investigated for the first time. After the utilization of garlic bulbs to prepare garlic oil or after drying the bulbs to produce garlic powder, garlic leaves are considered to be waste material, which is disposed of without any benefit. In this investigation, green garlic leaves were distilled and the essential oil was subjected to GC and GC-MS identification. The yield of the oil was 0.06% (based on wet weight of the leaves). The most prominent compounds of the essential oil were diallyl trisulfide (32.32%), followed by diallyl disulfide (31.35%) and methyl allyl trisulfide (11.40%); these compounds are the same as those found in garlic bulb oil. This means that garlic leaf oil is a rich, renewable and priceless source of garlic aroma compounds which could be utilized in fortification and enriching of garlic bulb essential oil to increase its quantity without changing the quality. Utilization of green garlic leaves for production of essential oil will also save, to some extent, the costs of disposing of large amounts of leaves in garlic possessing factories, transforming them into profits.     

Aroma profile and volatiles odor activity along gold cultivar pineapple flesh

Physicochemical attributes, aroma profile, and odor contribution of pineapple flesh were studied for the top, middle, and bottom cross-sections cut along the central axis of Gold cultivar pineapple. Relationships between volatile and nonvolatile compounds were also studied. Aroma profile constituents were determined by headspace solid-phase microextraction at 30 °C, followed by gas chromatography/mass spectrometry analysis. A total of 20 volatile compounds were identified and quantified. Among them, esters were the major components which accounted for 90% of total extracted aroma. Methyl butanoate, methyl 2-methyl butanoate, and methyl hexanoate were the 3 most abundant components representing 74% of total volatiles in pineapple samples. Most odor active contributors were methyl and ethyl 2-methyl butanoate and 2,5-dimethyl 4-methoxy 3(2H)-furanone (mesifuran). Aroma profile components did not vary along the fruit, but volatile compounds content significantly varied (P < 0.05) along the fruit, from 7560 to 10910 μg/kg, from the top to the bottom cross-sections of the fruit, respectively. In addition, most odor-active volatiles concentration increased from the top to the bottom 3rd of the fruit, concurrently with soluble solids content (SSC) and titratable acidity (TA) differences attributed to fruitlets distinct degree of ripening. Large changes in SSC/TA ratio and volatiles content throughout the fruit found through this study are likely to provoke important differences among individual fresh-cut pineapple trays, compromising consumer perception and acceptance of the product. Such finding highlighted the need to include volatiles content and SSC/TA ratio and their variability along the fruit as selection criteria for pineapples to be processed and quality assessment of the fresh-cut fruit.     

天然防腐剂在鲜切水果和果汁保鲜中的研究进展

随着国民生活水平的提高,人们对低热量食品的需求不断增大,即食鲜切水果和果汁的消费也逐渐增加,它们的安全性越来越受到人们的重视。鲜切水果和果汁由于组织和形态被破坏极易受到病原微生物和腐败微生物的污染,如果加工或储存条件不当,极易造成微生物致病和腐败。微生物学、酶学、化学或物理学变化均能引起鲜切水果与未高温消毒果汁的质量损失。其中,微生物造成的损失非常重要,有两方面原因:一是微生物毒素或病原微生物对消费者的健康构成威胁,二是微生物腐败给消费者造成经济损失。使用防腐剂可以有效减少微生物污染增强安全性。天然防腐剂既能保证食品安全又能保持品质特征,近年来,将其用于鲜切水果与未高温消毒果汁以防止微生物腐败方面的研究备受关注。本文综述了来自动物、植物和微生物的天然防腐剂对鲜切水果和果汁中病原微生物及腐败微生物的抑菌作用。     

Antibacterial Effects of Allspice, Garlic, and Oregano Essential Oils in Tomato Films Determined by Overlay and Vapor-Phase Methods

ABSTRACT:  Physical properties as well as antimicrobial activities against  Escherichia coli  O157:H7,  Salmonella enterica , and  Listeria monocytogenes  of allspice, garlic, and oregano essential oils (EOs) in tomato puree film-forming solutions (TPFFS) formulated into edible films at 0.5% to 3% (w/w) concentrations were investigated in this study. Antimicrobial activities were determined by 2 independent methods: overlay of the film on top of the bacteria and vapor-phase diffusion of the antimicrobial from the film to the bacteria. The results indicate that the antimicrobial activities against the 3 pathogens were in the following order: oregano oil > allspice oil > garlic oil.  Listeria monocytogenes  was less resistant to EO vapors, while  E. coli  O157:H7 was more resistant to EOs as determined by both overlay and vapor-phase diffusion tests. The presence of plant EO antimicrobials reduced the viscosity of TPFFS at the higher shear rates, but did not affect water vapor permeability of films. EOs increased elongation and darkened the color of films. The results of the present study show that the 3 plant-derived EOs can be used to prepare tomato-based antimicrobial edible films with good physical properties for food applications by both direct contact and indirectly by vapors emanating from the films.     

蒸制刀鲚肉挥发性成分的鉴定与分析

采用新型材料MonoTrap作为顶空固相萃取的吸附剂,提取不同水域刀鲚蒸制肉中的挥发性成分。利用气相色谱质谱联用仪（GC-MS）对长江刀鲚、东海刀鲚和黄河刀鲚蒸制鱼肉的挥发性成分进行分离鉴定。结合感觉阈值,利用相对气味活性值（ROAV）确定了蒸制刀鲚肉的主体呈香化合物,分析了其气味特征及生成途径。结果表明,长江刀鲚的主体呈香化合物由三甲胺（鱼腥味）、己醛（青草香）、1-辛烯-3-醇（蘑菇香）、壬醛（青草香,脂肪香）、二甲基三硫化物（蒜香,硫化物香）、癸醛（青草香,蜡香）组成;东海刀鲚的主体呈香化合物由1-辛烯-3-醇、三甲胺、己醛、壬醛、癸醛构成;黄河刀鲚的主体呈香化合物包括三甲胺、壬醛、2-壬烯醛（青草香,油脂香）、癸醛、2,4-癸二烯醛（脂肪香,油脂香）。      

Analysis of flavor volatile compounds by dynamic headspace in traditional and hybrid cultivars of Spanish tomatoes

A system specifically designed for the non-destructive analysis of volatile organic compounds in fresh tomatoes, based on a dynamic headspace technique, has been set up to quantify the volatile aroma constituents of tomato fruits. This system will reduce the high variability associated to sample selection in post-harvest studies. Volatile compounds with a major contribution to aroma have been quantitatively determined in two traditional tomato cultivars and one commercial F1 hybrid. One of the traditional cultivars, “De la Pera,” got the highest values of odor and aroma in sensory tests performed using a trained panel of 10 assessors. The same cultivar showed significantly higher contents of all eight volatile compounds studied (hexanal, trans-2-hexenal, cis-3-hexenol, 1-hexanol, 1-nitro-3-methylbutane, 6-methyl-5-hepten-2-one, 2-isobutylthiazole, and β-ionone). Significant differences among traditional and hybrid tomato cultivars can be detected for volatile compounds, thus allowing the use of volatile determination as a possible tool in tomato breeding programs.     

Antioxidant enrichment and antimicrobial protection of fresh-cut fruits using their own byproducts: looking for integral exploitation

Fresh-cut fruit consumption is increasing due to the rising public demand for convenience and awareness of fresh-cut fruit's health benefits. The entire tissue of fruits and vegetables is rich in bioactive compounds, such as phenolic compounds, carotenoids, and vitamins. The fresh-cut fruit industry deals with the perishable character of its products and the large percentage of byproducts, such as peels, seeds, and unused flesh that are generated by different steps of the industrial process. In most cases, the wasted byproducts can present similar or even higher contents of antioxidant and antimicrobial compounds than the final produce can. In this context, this hypothesis article finds that the antioxidant enrichment and antimicrobial protection of fresh-cut fruits, provided by the fruit's own byproducts, could be possible.     

Difference in volatile composition between the pericarp tissue and inner tissue of tomato (Solanum lycopersicum) fruit

Numerous studies have reported the volatile profiles in the whole fruit or pericarp tissue of tomato (Solanum lycopersicum) fruit; however, information is limited on the volatile composition in the inner tissue and its contribution to tomato aroma. For this, the pericarps and inner tissues of “Moneymaker,” “UglyRipe,” and “FL 47” fruits were separated before volatile analysis. Result showed that the volatile profiles were quite similar between the pericarp and inner tissue, suggesting the inner tissues also have a contribution to overall aroma quality. Besides the difference in volatile profile among cultivars, a higher concentration of alcohols was observed in the inner tissues of tomato fruit in comparison with that in the pericarp, which was associated with higher levels of 3‐methylbutanal, 2‐methylbutanal, 3‐methylbutanol, and 2‐methylbutanol in the inner tissue. These results also imply that different sampling methods might impact tomato aroma quality, which needs further verification via sensory penal.

Practical applications

The information on the volatile profile in the inner tissue and its contribution to tomato aroma is still rudimentary. In this study, the pericarp and inner tissue were separated from three tomato cultivars of different genetic background, and the volatile compositions were analyzed with HS‐SPME‐GC‐MS. Result showed that the volatile compositions were quite similar between the pericarp and inner tissue, suggesting that the inner tissues also have a contribution to overall aroma quality. Besides, a higher concentration of alcohols was observed in the inner tissues of tomato fruit in comparison with that in the pericarp, which was associated with higher levels of 3‐methylbutanal, 2‐methylbutanal, 3‐methylbutanol, and 2‐methylbutanol in the inner tissue. This study will provide the researchers and consumers some useful information on volatile composition in the inner tissue, its contribution to tomato aroma, and the impact of different sampling methods on the volatile profile.     

番茄果实的芳香物质组成及其影响因素研究进展

香气是番茄果实重要的感官品质之一,由果实中400多种具有挥发性的芳香物质协同产生,在很大程度上决定了商品等级和消费者的接受度。本文简述了番茄果实中的芳香物质及其在成熟过程中的变化趋势,总结了其合成途径,并重点介绍了影响番茄果实中芳香物质形成的因素,以期为研究者、生产者、销售者和消费者提供理论和生产实践方面的指导。     

冷破、热破番茄酱的香气特征及其与非挥发性组分之间的关系

番茄酱是一种重要的调味品,因其独特的口感和风味而广受消费者喜爱。本文以通过冷破（cold break,CB）、热破（hot break,HB）生产的8种番茄酱作为研究对象,采用顶空固相微萃取-气相色谱-质谱联用（headspace solid-phase microextraction-gas chromatography-mass spectrometry,HS-SPME-GC-MS）技术对其挥发性风味化合物的组成及相对含量进行分析,计算香气活度值（odor activity value,OAV）确定特征风味化合物,结合主成分分析（principal component analysis,PCA）以及相关性分析确定番茄酱中的香气成分与还原糖、有机酸、抗坏血酸以及果胶含量之间的关系。结果表明：不同破碎方法的番茄酱中挥发性风味化合物的组成及相对含量存在明显差别,8个样品中共鉴定出61种挥发性风味化合物,以醛类、醇类和酮类为主,其中22种为OAV≥1的香气活性化合物;CB番茄酱中的挥发性风味化合物组成及相对含量要显著（P<0.05）高于HB番茄酱,并且CB处理有利于保持番茄酱中较高的...     

Comparative study on essential oils incorporated into an alginate-based edible coating to assure the safety and quality of fresh-cut Fuji apples

Cinnamon, clove, and lemongrass essential oils (EOs) and their active compounds cinnamaldehyde, eugenol, and citral, respectively, were investigated for their effectiveness as antimicrobial agents in an alginate-based edible coating (EC) on fresh-cut Fuji apples. This EC also contained malic acid, N-acetyl-L-cysteine, glutathione, and calcium lactate as quality stabilizing compounds. The EC applied on apple pieces effectively maintained the physicochemical characteristics of the apple pieces for more than 30 days, decreased the respiration rate, reduced the Escherichia coli O157:H7 population by about 1.23 log CFU/g at day 0, and extended the microbiological shelf life by at least 19 days. The addition of EOs at 0.7% (vol/vol) or their active compounds at 0.5% (vol/vol) into the EC increased its antimicrobial effect, reduced the E. coli O157:H7 population by more than 4 log CFU/g, and extended the microbiological shelf life by more than 30 days. However, those concentrations of EOs affected the physicochemical characteristics of fresh-cut apples and thus limited their shelf life from 7 to 21 days. Lemongrass and cinnamon EOs (0.7%), citral (0.5%), and cinnamaldehyde (0.5%) were the most effective compounds for extending microbiological shelf life, whereas lemongrass, cinnamon, and clove EOs at 0.3% (vol/vol) best maintained the physicochemical characteristics of the product. Apple pieces with EC at day 0 and with EC with or without lemongrass EO at 0.7% at day 15 were preferred by the panelists. ECs containing natural antimicrobials and quality stabilizing compounds may be useful for extending the shelf life of fresh-cut fruits.     

SPME-GC-MS技术结合rOAV分析不同加工工艺紫娟白茶的关键香气物质

为研究不同加工工艺紫娟白茶的关键香气化合物,采用顶空固相微萃取-气相色谱-质谱联用技术(Headspace solid-phase micro extraction and gas chromatography mass spectrometry,HS-SPME-GC-MS),结合感官审评、PCA验证、OPLS-DA分析以及相对香气活度值(Relative odor activity value,rOAV),分析筛选紫娟白茶的关键香气化合物。结果表明:共检测出82种主要香气组分,以醇类、酯类、杂环及芳香族化合物为主,芳樟醇、水杨酸甲酯、苯甲醇、β-紫罗兰酮等相对含量较高,rOAV法分析结果显示:1-辛烯-3-醇、α-紫罗兰酮、苯乙醛、水杨酸甲酯等9种挥发性有机化合物对自然萎凋的紫娟白茶(TZW)花果香馥郁且带毫香、辛香、药香的香气形成具有较大贡献,1-辛烯-3-醇、α-紫罗兰酮、β-紫罗兰酮、苯甲醛等9种挥发性有机化合物对复式萎凋紫娟白茶(CZW)果香浓郁且带花香、辛香的香气形成具有较大贡献。OPLS-DA分析结合rOAV发现1-辛烯-3-醇和水杨酸甲酯是TZW与CZW香气差异的关键化...     

Antimicrobial silver-montmorillonite nanoparticles to prolong the shelf life of fresh fruit salad

In this work, silver-montmorillonite (Ag-MMT) antimicrobial nanoparticles have been obtained by allowing silver ions from nitrate solutions to replace the Na⁺ of natural montmorillonite and then to be reduced by a thermal treatment. Ag-MMT were used as active antimicrobial compounds to improve the shelf life of fresh fruit salad. In order to assess their influence on product shelf life, sensorial and microbiological quality has been monitored during the storage. The microbiological quality was determined by monitoring the principal spoilage microorganisms (mesophilic and psychrotrophic bacteria, coliforms, lactic acid bacteria, yeasts and molds). Additionally, the evolution of sensorial quality was assessed by monitoring color, odor, firmness and product overall quality. The Ag-MMT nanoparticles seemed to be effective in inhibiting microbial growth, above all at the highest tested concentration. Consequently, the sensorial quality of samples stored in the active packaging appeared to be better preserved. Thus, experimental results showed that a significant shelf life prolongation of fresh fruit salad can be obtained by a straightforward new packaging system.     

番茄（Solanum lycopersicum）果皮和果肉挥发物及香气比较

为探究番茄果皮和果肉挥发物以及香气的差异，以挥发物浓度高的自交系CI1005（红色樱桃番茄）和浓度低的自交系TI4001（绿色普通大果番茄）为材料，采用顶空固相微萃取-气相色谱-质谱-嗅闻法分析番茄绿熟期、转色期、橙熟期和红熟期果皮和果肉挥发物组分及其浓度，描述气味特征及其强度。结果表明，果实成熟过程中，同一自交系果皮和果肉挥发物组分差异较小。每个成熟阶段，CI1005果皮挥发物浓度均显著高于果肉，尤其是醛类、醇类、酮类、酯类和酸类挥发物；TI4001果肉挥发物浓度均显著高于果皮，特别是醛类、酯类和酸类挥发物。CI1005果皮香气强度显著高于果肉，尤其是清香、脂香和麦芽香；果肉仅甜感强于果皮。果皮清香最浓，果肉果香最浓。果实成熟过程中，果皮香气比果肉增加得多，红熟期差异最大。TI4001果肉香气强度显著高于果皮，特别是脂香、蘑菇香和清香。果肉脂香最浓，果皮花香最浓。转色期果皮和果肉香气均最浓，二者香气差异最大。CI1005挥发物组分和浓度及其香气强度均显著高于TI4001。总之，果皮和果肉中挥发物和香气差异显著。     

Impact of plant essential oils on microbiological,organoleptic and quality markers of minimally processed vegetables

The objectives of this study were to evaluate the efficacy of plant essential oils (EOs) for control of the natural spoilage microflora on ready-to-eat (RTE) lettuce and carrots whilst also considering their impact on organoleptic properties. Initial decontamination effects achieved using EOs were comparable to that observed with chlorine and solution containing oregano recorded a significantly lower initial TVC level than the water treatment on carrots (p < 0.05). No significant differences were found between the EO treatments and chlorine considering gas composition, color, texture and water activity of samples. The sensory panel found EO treatments acceptable for carrots throughout storage, while lettuce washed with the EO solutions were rejected for overall appreciation by Day 7. Correlating microbial and sensory changes with volatile emissions identified 12 volatile quality markers. Oregano might be a suitable decontamination alternative to chlorine for RTE carrots, while the identification of volatile quality markers is a useful complement to sensory and microbiological assessments in the monitoring of organoleptic property changes and shelf-life of fresh vegetables.Industrial relevanceThere is industrial demand for natural alternatives to chlorine, which is commonly used for decontamination of fresh produce but which has limitations with respect to antimicrobial efficacy and possible formation of carcinogenic compounds in water. Plant essential oils have proven antimicrobial and other bioactive properties, however their usefulness in foods can be mitigated by their high sensory impact. This study examined the application of EOs for fresh produce decontamination addressing control of spoilage microflora and improving shelf-life characteristics whilst also considering the impact on organoleptic properties. The effectiveness of oregano as a decontamination treatment was comparable with that of chlorine. Carrot discs treated with the EO regimes were acceptable in terms of sensory quality and appreciation, therefore oregano could offer a natural alternative for the washing and preservation of fresh produce. Combining EOs with other natural preservatives might minimize doses and reduce the impact on organoleptic properties of fresh vegetables.     

Changes of the sensorial attributes of white wines with the application of new anti-mildew fungicides under critical agricultural practices

Although the winemaking process could allow the dissipation of residues of fungicides applied under critical agricultural practices (CAP), their residual levels could alter the biosynthesis of volatile compounds. The purpose of this work is to look for changes in the aroma profile of those wines in comparison with wines treated under good agricultural practices (GAP). Four new fungicides (mandipropamid, valifenalate, cyazofamid and famoxadone), used to control downy mildew (Plasmoparaviticola), were applied under CAP in an experimental vineyard producing white grapes (Vitisvinifera) of Godello var. Once grapes were harvested, single vinifications were performed. Possible modifications of sensorial properties of wines were evaluated by a trained sensorial testing panel constituted of 7 experts. The fungicide residues induced an increment of typical fermentative odours associated with esters in treated wines. The critically treated wine was moved to a sweeter balance with a ripe fruit taste, associated with higher viscosity and greater cloudiness.