Recent advances in extending the shelf life of fresh Agaricus mushrooms: a review

Postharvest browning of Agaricus mushrooms is a severe problem that reduces the shelf life of harvested mushrooms because of their continued respiration and biochemical activity. There are no simple answers and no single treatment is known to limit overall quality deterioration. However, there are several strategies that are being implemented in order to reduce the rate of respiration for mushrooms. Packaging technology is the common denominator that allows us to implement these strategies and thus is key to quality preservation. In this review, first, the major factors involved in postharvest quality deterioration are discussed and then technological advances/methods used to counteract these hurdles are presented. Copyright © 2010 Society of Chemical Industry     

护色处理对冻藏香蕉片多酚氧化酶活性的影响

通过设计单一护色剂、不同浓度L-半胱氨酸、不同热处理时间及多因子护色处理四个实验研究其对冻藏香蕉片多酚氧化酶(PPO)活性的影响,结果表明,5种护色剂均能有效地抑制冻藏香蕉片PPO活性,但L-半胱氨酸对其抑制效果更佳;随着护色液中Cys浓度的增加,残余PPO活力呈下降趋势,表现为CK>0.05%Cys>0.1%Cys>0.2%Cys;热处理能有效地抑制冻藏香蕉片PPO活性,PPO活性随着热处理时间的增加而降低,但热处理却大大降低了冻藏香蕉片的品质;0.1%L-半胱氨酸、0.05%异抗坏血酸、0.1%蔗糖和0.1%氯化钙构成的护色剂组合能有效地抑制PPO活性,并起到良好的保质增脆效果。     

Biochemical changes of fresh-cut pineapple slices treated with antibrowning agents

The effectiveness of ascorbic acid (AA), isoascorbic acid (IAA) and N‐acetyl‐cysteine (AC) in inhibiting browning of fresh‐cut pineapple slices that were stored for up to 14 days at 10 °C, were studied. Slices treated with IAA and AA maintained higher levels of sugars and vitamin C than AC and controls. A low reduction of total phenolic content in treated slices was correlated with a lower polyphenol oxidase activity. IAA and AA slowed the degradation rates of sugars, vitamin C, and phenolic content, whereas AC was less effective in affecting these processes. A higher content of AA and IAA was associated with better compositional quality parameters and appearance of the pineapple slices during the storage period.     

Use of UV-C treatments to maintain quality and extend the shelf life of green fresh-cut bell pepper (Capsicum annuum L.)

Abstract: The objective of this work was to select a Ultraviolet‐C (UV‐C) treatment for fresh‐cut mature green bell pepper, and to evaluate the effect of its combination with refrigeration on quality maintenance. Bell pepper sticks were treated with 0, 3, 10, or 20 kJ/m² UV‐C in the outer (O), inner (I), or both sides of the pericarp (I/O) and stored for 8 d at 10 °C. During the first 5 d of storage, all UV‐C treatments reduced deterioration as compared to the control. The treatment with 20 kJ/m² I/O was the most effective to reduce deterioration, and was used for further evaluations. In a second group of experiments, mature green bell pepper sticks were treated with 20 kJ/m² I/O, stored at 5 °C for 7 or 12 d and assessed for physical and chemical analysis, and microbiological quality. UV‐C‐treated fruit showed lower exudates and shriveling than the control. UV exposure also reduced decay, tissue damage, and electrolyte leakage. After 12 d at 5 °C, UV‐C irradiated peppers remained firmer and had higher resistance to deformation than the control. The UV‐C treatments also reduced weight loss and pectin solubilization. UV‐C exposure decreased the counts of mesophile bacteria and molds, and did not affect acidity or sugars. UV‐C‐treated fruit stored for 0 or 7 d at 5 °C did not show major differences in antioxidants from the control as measured against DPPH^? or ABTS^?+ radicals. Results suggest that UV‐C exposure is useful to maintain quality of refrigerated fresh‐cut green pepper. Practical Application: Exposure to UV‐C radiation before packing and refrigeration could be a useful nonchemical alternative to maintain quality and reduce postharvest losses in the fresh‐cut industry.     

Untargeted metabolomics to explore the oxidation processes during shelf life of pork patties treated with guarana seed extracts

The changes of metabolites in pork patties with different antioxidants added (control without antioxidants, 200 mg kg⁻¹ butylated hydroxytoluene (BHT) and 250 mg kg⁻¹ guarana seed extracts (GSEs)) under modified atmosphere (80% O₂ and 20% CO₂) for 18 days of refrigerated storage were evaluated. Untargeted metabolomic approach based on UHPLC-ESI-QTOF-MS analysis was applied. GSE phytochemical profile revealed a wide variety of compounds (caffeine, glycerol 1-propanoate, amino acids, alkaloids and glycerophospholipids), together with antioxidants (tyrosols, procyanidins and flavonoids). Important differences in BHT and GSE patties metabolomic profiles were found during storage. Most of the differences could be attributed to glycerophospholipids and fatty acyls, along with specific compounds derived from lipid oxidation (i.e. 2-hexenal, 4-hydroxy-2-hexenal and 2,4-heptadienal) and protein degradation (spermine). Therefore, the approach used highlighted a modulation of lipid oxidative processes, together with strict correlation between metabolic profiles and factors associated with meat quality, highlighting GSE effect on active compounds delaying oxidative phenomena.     

The use of pullulan coatings with propolis extract to extend the shelf life of blueberry (Vaccinium corymbosum) fruit

Consuming fresh blueberries has many health benefits due to the extremely high level of phytonutrients. During storage, the berries spoil due to microbial contamination. The aim of the work was to investigate the effect of pullulan coating containing 5% and 10% propolis extract on reducing the number of bacteria and mould and on the physicochemical properties of coated blueberries during storage. The results showed that the count of microorganisms was reduced by 3–4.5 logarithmic cycle after 21 days (16°C, RH of 58–63%). It was also found that coatings delayed blueberry ripening as well as decreased weight loss. During storage, minor increase were found in titratable acidity values and no change the total soluble solid values in blueberries covered with pullulan coating containing propolis extract in comparison with the uncoated ones. Thus, the pullulan coating with propolis extract has the potential as microbiological protection for blueberry fruit.     

Effect of Natural Antibrowning Agents on Color and Related Enzymes in Fresh-Cut Fuji Apples as an Alternative to the Use of Ascorbic Acid

ABSTRACT:  Polyphenoloxidase (PPO) and peroxidase (POD) were evaluated in fresh-cut Fuji apple slices and the effect of the individual or combined use of ascorbic acid, 4-hexylresorcinol, N-acetylcysteine, and glutathione on their respective activities was determined. Additionally, color changes during storage at 4 °C were measured throughout 14 d of storage. PPO activity increased with storage time and was inhibited by the individual use of N-acetylcysteine and glutathione. POD activity in the apple slices was effectively inhibited by the combined use of ascorbic acid with any of the other antibrowning agents. On the other hand, an individual treatment with 1% N-acetylcysteine helped in maintaining the color of fresh-cut apples during 14 d of storage, whereas the use of ascorbic acid was not enough to prevent color deterioration of the apple slices from the 1st day of storage. The results obtained corroborated the effectiveness of other natural antibrowning agents over the traditional use of ascorbic acid in the control of the enzymatic browning in the fresh-cut fruit industry.     

Fatty acids,volatile compounds and microbial quality preservation with an oregano nanoemulsion to extend the shelf life of hake (Merluccius hubbsi) burgers

Hake (Merluccius hubbsi) is the most important fish of Argentinean industry. The preservative effects of an oregano essential oil (EO) nanoemulsion (NE) on hake burgers (FB) during 15 days at 4 °C were studied. Fatty acids determined by gas chromatography coupled with mass spectrometry (CG-MS), volatile compounds determined by solid phase microextraction (SPME) coupled with CG-MS, total volatile basic nitrogen (TVBN), and microbial count was measured. ANOVA and DCG tests were performed. After 14 days, significant differences were detected among samples (P ≤ 0.05). FB with EO (EO-FB) and FB with NE containing EO (NEEO-FB) had the highest content of EPA (eicosapentaenoic acid) (191.82 and 198.42 g kg⁻¹) and DHA (docosahexaenoic acid) (107.97 and 110.87 g kg⁻¹, respectively). Also, NEEO-FB had the lowest microbial count (7 log CFU g⁻¹). The incorporation of the oregano essential oil into a nanoemulsion improves the preserving activity in hake fish burgers.     

Methyl jasmonate coupled with modified atmosphere packaging to extend shelf life of tomato (Lycopersicon esculentum Mill.) during cold storage

The effects of methyl jasmonate coupled with modified atmosphere packaging (MJ+MAP) on the quality and shelf life of mature green tomato ( Lycopersicon esculentum Mill.) were investigated during cold storage at 5 °C. Tomatoes were treated with 10⁻⁴  m MJ and packaged under 5%O₂/5%CO₂/90%N₂ in a plastic bag. The effects of MJ+MAP were compared with control as well as heat treated (HT) samples. Control samples were tomatoes packaged under atmospheric air. HT samples were prepared by dipping tomatoes in hot water at 50 °C for 3 min and packaged under atmospheric air. The results showed that MJ+MAP and HT could delay ethylene production during tomato ripening and consequently slowed down the softening rate. MJ+MAP tomatoes showed better quality and less chilling injury (CI) symptoms than HT and control samples. Based on a nine-point score, shelf life criteria assumed that rejection would occur when the sensory attributes declined below 5. Control and HT overall acceptance scores were shown to fall below 5 scores after 3 and 6 weeks storage, while MJ+MAP had overall acceptance scores above 5 for up to 9 weeks. Control and HT samples could be stored for about 4 and 6 weeks, respectively, while MJ+MAP tomatoes could be stored for up to 9 weeks.     

Potential of oregano essential oil and MAP to extend the shelf life of fresh swordfish: a comparative study with ice storage

ABSTRACT:  The present study evaluated the effect of modified atmosphere packaging (MAP, 5% O₂/50% CO₂/45% N₂; treatment M), the addition of oregano oil (0.1%, v/w; treatment AO) as a natural preservative, as well as their combination (treatment MO) on the quality and shelf life extension of fresh Mediterranean swordfish fillets during a refrigerated storage (4 °C) period of 18 d. Simultaneously, swordfish fillets were stored under aerobic conditions (control treatment A, 4 °C) and on ice (usual commercial method of preservation, treatment I, 0 °C). Among the 5 treatments examined in the present study, the most effective one to inhibit the microbial and sensory spoilage proved to be the MO treatment, achieving a shelf life extension of 8 to 9 d. The dominant bacteria in the microflora of swordfish, irrespective of treatment, were the Pseudomonads and the H₂S-producing bacteria, while both lactic acid bacteria (LAB) and the Enterobacteriaceae produced the lowest populations in swordfish samples kept on ice. Among the chemical indices examined, thiobarbituric acid (TBA) values showed no specific trend of lipid oxidation for swordfish, irrespective of treatment. Final trimethylamine nitrogen (TMA-N) and total volatile basic nitrogen (TVB-N) values for treatments, A, AO, M, and MO ranged between 1.33 and 14.29 mg N/100 g and 14.11 to 55.52 mg N/100 g, respectively, whereas for I samples they remained almost unchanged during storage. Sensory analysis (taste attribute) correlated well with microbiological analysis, indicating a shelf life of approximately 5 to 6 d for control, 10 to 11 d for AO, 12 d for I, 13 d for M, and 14 d for MO samples.     

Display life of beef packaged with an antioxidant active film as a function of the concentration of oregano extract

Fresh beef steaks were packaged with a new antioxidant active system containing increasing concentrations (0.5, 1, 2 and 4%) of an oregano extract. Control samples were packaged without the active film. Additional samples were sprayed with the extract and packaged as the control samples. Packages were filled with a 80%O(2)/20%CO(2) atmosphere and displayed under illumination (14 h) at 1 ± 1 °C for 28 days. Metmyoglobin formation, lipid oxidation (TBARS), instrumental colour (CIE a*) and sensory colour, discoloration, off-odour and oregano smell were determined. Active packaging significantly (P < 0.05) enhanced oxidative stability of beef steaks, depending on the oregano concentration of the active film. The display life of beef samples demonstrated that at least 1% oregano was needed for obtaining a significant increase of display life from 14 to 23 days. A concentration of 4% gave rise to unacceptable oregano smell. As a consequence, most suitable oregano extract concentrations for optimum active packaging in this system should be within the range 1-2%.     

Functional and organic eggs as an alternative to conventional production: a conjoint analysis of consumers' preferences

BACKGROUND: In the current context of growing consumer demand for foodstuffs that are healthy and safe and that are obtained in a manner respectful to the welfare of animals, the analysis of consumer preferences towards attributes of this type takes on particular importance. These trends are especially clear in the case of the consumption of eggs because of their strong negative association with cholesterol levels and their extremely intensive systems of production. The introduction of variants that are more in harmony with current consumer demands represents an interesting market alternative. RESULTS: The present study was aimed at investigating the preferences of Spanish consumers for these alternative types of egg that are entering the market. The survey was conducted with 361 consumers from October 2007 to March 2008. The conjoint analysis allowed us to estimate the relative importance of the main attributes that affect consumer preferences for eggs and to distinguish segments of consumers with similar preference profiles. CONCLUSION: It was found that price is the most important attribute determining consumer preferences, followed by the hens' feed and their rearing conditions. It was also found that only some groups of consumers are willing to pay the premium necessary for alternative methods of production. Copyright © 2010 Society of Chemical Industry     

南美白对虾产业发展报告

为研究乳酸链球菌素（Nisin）对高水分烤虾常温下贮藏性的影响,在烤虾样品中分别添加20、60和100 mg/kg的Nisin,以感官结合菌落总数、蜡样芽孢杆菌数、挥发性盐基氮、pH等指标对样品品质进行评价。结果表明,烤虾的感官评分在常温贮藏过程中逐渐下降,菌落总数、蜡样芽孢杆菌数、挥发性盐基氮与pH则呈增长趋势。随着Nisin添加量的增加,菌落总数、蜡样芽孢杆菌数、挥发性盐基氮的增长趋慢。第6 d时,未加Nisin的对照组样品菌落总数达到行业标准《调味烤虾》中规定的限值（3×10⁴ CFU/g）,而添加20、60、100 mg/kg Nisin的样品,菌落总数达到规定限值的时间分别被延长至8、12和14 d。本研究表明Nisin对高水分烤虾中蜡样芽孢杆菌等腐败微生物生长有明显的抑制作用,能有效延长产品的货架期。     

Reassessment of treatments to retard browning of fresh‐cut Russet potato with emphasis on controlled atmospheres and low concentrations of bisulphite

The cultivar Pacific Russet with high browning susceptibility was used for most testing. Controlled atmospheres (0.3%, 3% and 21% O₂ in combination with 0%, 6% or 12% CO₂) and anti‐browning chemicals were studied in relation to quality retention and wound‐induced phenolic metabolism of fresh‐cut slices for up to 16 days at 5 °C. The 3% O₂+ 12% CO₂ atmosphere was most effective among those tested, and retarded increases in phenolics and phenylalanine ammonia lyase activity, but had only slight benefit on visual quality. A 1.25% ascorbic acid +1.25% citric acid treatment was ineffective, but when combined with 3% O₂+ 12% CO₂, it was comparable with 0.025% sodium bisulphite. Bisulphite concentrations from 0.05% to 0.25% provided similar effective control of discolouration. Bisulphite as low as 0.025% with 3% O₂+ 12% CO₂ resulted in a visual quality score at the limit of marketability after 8 days at 5 °C. Chemical treatments did not retard increases in phenolic concentrations or phenolic enzyme activities.     

Fatty acid and sugar composition of avocado,cv. Hass,in response to treatment with an ethylene scavenger or 1-methylcyclopropene to extend storage life

This study reports on the effect of 1-methylcyclopropene (1-MCP) and a newly developed palladium (Pd)-promoted ethylene scavenger (e + ® Ethylene Remover) on changes in firmness, colour, fatty acids and sugar content of early and late season avocado (Persea americana Mill.), cv. Hass, during storage at 5 °C and subsequent ripening at 20 °C. The e + ® Ethylene Remover effectively delayed ripening of avocado stored at 5 °C. 1-MCP was more effective at inhibiting ripening, but, in contrast to e + ® Ethylene Remover, it impaired subsequent ripening. Fatty acid profile of late season fruit remained unchanged in response to treatments or storage time, whilst that of early season fruit was slightly, yet significantly, different according to treatments and storage time. Substantial amounts of perseitol were found in all fruit. In contrast, mannoheptulose was only present at high concentration in early season fruit whilst it was quasi-absent in late season fruit. Where ripening was inhibited in response to 1-MCP treatment, significantly more mannoheptulose and better maintenance of perseitol was found vs. controls. Similarly, but to a lesser extent and concomitant with trends in firmness retention and colour changes, e + ® Ethylene Remover led to greater maintenance of mannoheptulose and perseitol than that of controls. This is the first piece of research comparing effects of ethylene removal vs. ethylene action blocking on physical and biochemical changes in avocado cv. Hass and supports the view that C7 sugar metabolism could be an important feature of the avocado fruit-ripening process.