Estimating packaging atmosphere–temperature effects on the shelf life of cod fillets

The behaviour of the natural microflora (total bacterial count, psychrotrophic bacteria, total coliforms, and lactic acid bacteria) of fresh cod fillets packaged in air, under vacuum, in a modified atmosphere with low oxygen concentration (5%) and in a modified atmosphere with high oxygen concentration (80%) was monitored during storage at different isothermal conditions from 4 to 12 °C. The growth data of the total bacterial count and total coliforms were used to model kinetically the shelf life of the samples in order to check the effects of storage temperature and packaging atmosphere. The acceptability times were compared with the stability times to establish if the shelf lives predicted were correlated. At 4 °C, cod fillets packaged under vacuum and in a modified atmosphere with low oxygen concentration had a higher shelf life (6.00 and 5.42 days), calculated from the growth of the total bacterial count, than the samples packaged in other atmospheres (1.96 and 2.62). Kinetic modelling could be valuable for the prediction of microbial fish quality loss.     

Shelf life of fresh-cut Cime di rapa (Brassica rapa L.) as affected by packaging

In this work, the effectiveness of different packaging in prolonging the shelf life of fresh-cut Cime di rapa (Brassica rapa L.) was addressed. Two subsequent experimental trials were run to investigate first the ability of different packaging materials (an oriented polypropylene, a blend of biodegradable polyesters and a nylon/polyethylene multilayer) in delaying the quality loss and then to assess the efficacy of modified atmosphere packaging (MAP). Two different combinations of gas were investigated, oxygen 10%, carbon dioxide 2% and nitrogen 88%, noted as MAP1 and oxygen 8%, carbon dioxide 2% and nitrogen 90%, noted as MAP2. Headspace gas concentration, weight loss, spoilage microbial growth, pH and sensorial quality were monitored in both sets of experiments. The results demonstrated that the best performances under ordinary atmosphere were recorded with the oriented polypropylene-based film, justifying the choice of this polymeric material in the second set-up. The tested MAPs exerted somewhat different results on product quality: the samples packaged under MAP1 recorded a shelf life of 14 days limited by visible moulds, whereas, fresh-cut leaves sealed under MAP2 highlighted a shelf life less than 9 days, due to a high proliferation of total mesophilic bacteria.     

Shelf life extension of durum semolina‐based fresh pasta

In this work, the combined effects of chitosan, modified atmosphere packaging (MAP) and packaging barrier properties on shelf life of fresh pasta is presented. In particular, all pasta samples were packaged under active and passive MAP in two different polymeric films with high and low barrier properties. In order to assess the influence of the variables described beforehand on the shelf life of pasta, the sensorial and microbiological quality has been monitored during storage. Results confirmed the antimicrobial properties of chitosan. Moreover, the findings recorded in this study suggest that the shelf life of fresh pasta is limited by the sensorial characteristics. Statistically significant differences between the shelf life of pasta packaged in low barrier and high barrier films were found. The best result was obtained for samples packaged in high barrier film, due to the ability of the packaging to maintain the gas headspace conditions during the storage.     

Development of edible bioactive coating based on modified chitosan for increasing the shelf life of strawberries

For increasing the shelf life of strawberries during storage, bioactive coatings were applied using modified polysaccharides of chitosan. First, antimicrobial tests were performed with selected essential oils to evaluate their antimicrobial capacities against moulds and total flora isolated from strawberries. Red thyme (RT) and oregano extract (OR) were found as strong bioactive agents against moulds and total flora isolated from strawberries, whereas limonene (LIM) and peppermint (PM) had lower antimicrobial properties. These essential oils were also used as bioactive compounds which were sprayed onto strawberries and evaluated for their potential to increase shelf life during storage at 4 °C. RT, PM and LIM were found to be more efficient preservative agents for strawberries during 14 days of storage. Finally, chitosan was functionalized by acylation with palmitoyl chloride to increase its hydrophobicity, to ensure a controlled release and improve its stability and adhesion to the fruit product. LIM and PM were incorporated into the modified chitosan to create bioactive edible coatings and these were tested for their ability to extend the shelf life of fresh strawberries during storage. Formulations based on modified chitosan containing LIM and Tween®80 were shown to perform better than other formulations.     

低温结合气调包装处理对鲜切胡萝卜品质的影响

该研究以鲜切胡萝卜为对象,采用低温结合气调包装对鲜切胡萝卜进行处理,研究不同保鲜方式对鲜切胡萝卜品质的影响。鲜切胡萝卜经气调(气体组成分别为5%O₂+5%CO₂+90%N₂、5%O₂+10%CO₂+85%N₂、10%O₂+5%CO₂+85%N₂)包装后,(4±1)℃下在保鲜盒中贮藏,每3 d测定感官品质、失重率、可溶性固形物含量、抗坏血酸含量、胡萝卜素含量、菌落总数、丙二醛(malondialdehyde,MDA)含量和以及超氧化物歧化酶(superoxide dismutase,SOD)和过氧化氢酶(catalase,CAT)活性等指标。结果表明,低温结合5%O₂+10%CO₂+85%N₂气调包装处理组有效地保持了鲜切胡萝卜的品质,减少了水分的流失,延缓了营养物质可溶性固形物、胡萝卜素以及抗坏血酸含量的下降,抑制了MDA含量...     

Effects of Antimicrobial Edible Coating of Thymol Nanoemulsion/Quinoa Protein/Chitosan on the Safety,Sensorial Properties,and Quality of Refrigerated Strawberries (<Emphasis Type="Italic">Fragaria × ananassa</Emphasis>) Under Commercial Storage Environment

The effectiveness of the edible coating with thymol nanoemulsion on the safety, sensorial properties, and quality of refrigerated strawberries was investigated under commercial storage conditions. Spontaneous emulsification was used to obtain the thymol nanoemulsion that was included on quinoa protein/chitosan coatings. During the entire storage time, strawberries coated with thymol-antimicrobial packaging had a lower fungal and yeast load compared with the controls (uncoated and coated with quinoa protein/chitosan). The flavour and aroma of the coated strawberries was initially affected, although this sensory appreciation was improved from the fifth day of storage and showed similar scores than the controls, and presenting better aroma score at day 12 of storage. Furthermore, the shelf life of the thymol nanoemulsion-coated strawberries increased in 4 days, unlike that in the both controls. Further, the application of these biocoatings on strawberries significantly decreased the weight loss relative to that in the control, during 16 days of storage at 5 °C and 90% relative humidity, and did not alter the quality parameters (pH, titrable acidity, and percentage of soluble solids). These results suggest that the application of thymol/nanomulsion-loaded edible films is an effective strategy to increase the shelf life of highly perishable products such as strawberries.     

Development of a multilayered antimicrobial edible coating for shelf-life extension of fresh-cut cantaloupe (Cucumis melo L.) stored at 4 °C

The objective of this study was to develop a multilayered edible coating with antimicrobial agent to extend the shelf life of fresh-cut cantaloupe stored at 4 °C. Three different sets of experiments were designed to test the effect of different concentrations of chitosan (0.5, 1, 2 g/100 g), pectin (0.5, 1, 2 g/100 g), and encapsulated trans-cinnamaldehyde (1, 2, 3 g/100 g), on the quality of fresh-cut cantaloupe. The first set (chitosan concentrations) provided the optimum concentration of chitosan based on preferences by the panelists. The second set (pectin concentrations) produced an acceptable coating that maintained shelf life. The third set (antimicrobial concentrations) helped establish the optimum concentration of trans-cinnamaldehyde in the coating. Changes in fruits texture, color, moisture, acidity, and pH were monitored. Sensory testing was carried out to support the objective quality data and microbiological analysis helped verify the antimicrobial effectiveness of trans-cinnamaldehyde. Uncoated fresh-cut cantaloupes stored at 4 °C served as controls. To test for the antimicrobial activity of chitosan alone, a second set of controls consisted of samples coated only with chitosan.     

Minimally processed butternut squash shelf life

The effects of dipping in antimicrobial solution and efficacy of proper film and modified atmosphere packaging conditions (MAP) on the quality decay of packaged fresh-cut butternut squash were investigated. The work was divided into three subsequent experimental trials: the first two were aimed to select the optimal packaging film mass transport properties, being micro-perforated and no-perforated films been tested. In the third experimental step, the best film (i.e., no-perforated oriented polypropylene, OPP40) was used to package sliced butternut squash under passive and active MAP. Each slice of product was dipped in aqueous solution of potassium sorbate, while no dipped samples were stored as the controls. During storage at refrigerated temperature (4 ± 1 °C) headspace gas concentrations, mass loss, microbiological and sensory quality were monitored. Results obtained from the preliminary pre-screening showed that micro-perforated films did not match fresh-cut butternut squash respiratory requirements. In these films a high proliferation of moulds occurred, probably due to elevated oxygen levels. Among the no-perforated films with different thickness, the OPP40 showed better performances. In the third trial samples dipped in potassium sorbate and packaged in OPP40 under active MAP recorded a shelf-life of about 22 days respect to the no-dipped samples packaged under both passive and active MAP that reached a shelf life of about 2 weeks.     

自发气调包装对鲜切白菜货架期的影响

为延长鲜切白菜的货架期,本文采用不同透气率和不同面积的气调窗与包装袋相结合进行试验,通过对鲜切白菜包装袋内感官品质、气体成分进行统计和分析,筛选和优化出鲜切白菜最适宜的气调包装。结果表明：自发气调包装可有效改善鲜切白菜贮藏品质,鲜切白菜适宜选用O2和CO2透过速率分别为4×105和1.6×106 cm3/m2?d?atm,透气比为1:4气调窗,所需要气调窗的面积为1~2 cm2/kg,在4 ℃条件下至少可延长货架期4 d;综合计算气调窗和薄膜的透气量可知,适于鲜切白菜包装袋O2和CO2的透过量应分别为1.85×103~2.08×103 和8.59×103~9.51×103 cm3/kg?d?atm,达到鲜切白菜的适宜气体浓度,O2为3.63%~5.10%,CO2为7.77%~8.07%。研制的自发气调包装袋可使鲜切白菜处于适宜的气体状态,可很好地解决包装袋内由于无氧呼吸产生的异味问题,且保留原有的鲜切白菜气味,延长其货架期,为鲜切企业提供有力的技术支持。     

Shelf life extension of fresh ginseng roots using sanitiser washing,edible antimicrobial coating and modified atmosphere packaging

Fresh American ginseng roots were washed with sanitiser solution (200 ppm sodium hypochlorite), surface‐coated with a coating solution consisting of 0.5% chitosan and three organic acids (lactic, levulinic and acetic acids) and then placed in modified atmosphere packaging (MAP) with 5% O₂, 10% O₂ or ambient air. Total aerobic bacteria, yeasts and moulds, weight loss and quality changes (texture, colour and appearance) of roots were monitored during storage at 4 °C. Throughout the 38‐week study, there were no significant changes in microbial loads, texture, colour and appearance of samples after sanitiser washing and coating treatments and packaged with air, 5% O₂ or 10% O₂. The weight loss of roots after 38 weeks was approximately 3%. The results demonstrate that the unique coating formulation (0.5% chitosan and multiple organic acids) and combination of sanitiser washing, coating treatment and MAP extend the shelf life of fresh ginseng roots to at least 38 weeks.     

Combined effect of active coating and MAP to prolong the shelf life of minimally processed kiwifruit (Actinidia deliciosa cv. Hayward)

In this work different strategies aimed to prolong the shelf life of minimally processed kiwifruits are presented. First, the effectiveness of several treatments in delaying the quality loss of the investigated produce packaged under passive MAP was addressed; afterward, the treatments that have shown the best performances were used to assess the effectiveness of active MAP in prolonging the packaged produce shelf life. Different treatments such as coating with sodium alginate in combination with dipping into an hydro-alcoholic solution (Coat-dipp-EtOH), dipping into an hydro-alcoholic solution (Dipp-EtOH) and coating with sodium alginate containing grape fruit seed extract solution (Coat-GFSE) were investigated. The untreated samples were used as control. Headspace gas concentrations, pH, mass loss, sensory quality and viable cell load of main spoilage microorganisms were monitored in both the experimental steps. Results suggested that the best performances under passive MAP were recorded with the coating treatments, justifying the choice of this treatment in the second step. In fact, the coatings were more effective in delaying dehydration and slowing down respiratory activity of minimally processed kiwifruits both in passive and active MAP. The combination of active compounds with alginate-based coating delayed the microbial growth whereas the sole dipping treatment was inefficient. In particular, a viability loss of the mesophilic and psychrotrophic bacteria of about 2 log cycle for the coated samples with respect to control and dipped samples was found. However, as the microbial load was always found below the threshold value imposed by law, the sensorial acceptability limit of the packaged fresh-cut produce coincided with its shelf life. Alginate-based coating reduced respiratory activity, as well as sensory decay, increasing the sensorial acceptability limit of the samples packaged under passive MAP up to 12 days with respect to the control (8 days). For the samples packaged under active MAP, the coating treatments reduced the excessive dehydration of the produce due to the MAP conditions. In fact, when the active MAP was used alone a very short shelf life of the uncoated samples occurred (2.7 days). Whereas, the combined use of active MAP and coating treatments prolonged the produce shelf life up to 13 days.     

Combined effect of active coating and modified atmosphere packaging on prolonging the shelf life of low-moisture Mozzarella cheese

In this work, the effect of active coating on the shelf life of low-moisture Mozzarella cheese packaged in air and modified atmosphere (MAP) was studied. The active coating was based on sodium alginate (2%, wt/vol) and potassium sorbate (1%, wt/vol). The MAP was made up of 75% CO₂ and 25% N₂ (MAP1), 25% CO₂ and 75% N₂ (MAP2), or 50% CO₂ and 50% N₂ (MAP3). The product quality decay was assessed by monitoring microbiological and sensory changes during storage at 4, 8, and 14°C. Results showed that the combination of active coating and MAP was able to improve the preservation of low-moisture Mozzarella cheese. Specifically, the shelf life increased up to 160 d for samples stored at 4°C, and 40 and 11 d for those at 8 and 14°C, respectively. A faster quality decay for untreated samples packaged in air was observed. In particular, the Pseudomonas spp. growth and the appearance of molds were responsible for product unacceptability. The combination of active coating and MAP represents a strategic solution to prolong the shelf life of low-moisture Mozzarella cheese and to ensure the safety of the product under thermal abuse conditions.     

包装材料对鲜切西兰花贮藏品质的影响

为了延长西兰花货架期,采用4 种膜包装鲜切西兰花,研究其在贮藏期品质的变化。将鲜切西兰花分别用 聚偏二氯乙烯（polyvinylidene chloride,PVDC）、聚乙烯（polyethlene,PE）、低密度PE、聚甲基戊烯4 种膜 包装,贮藏期间每3 d测定西兰花生理生化指标。结果表明：随着贮藏时间的延长,西兰花的品质逐渐下降;贮 藏12 d时,采用PVDC膜包装的西兰花的VC含量、可溶性固形物质量分数、过氧化物酶活力最高,质量损失率、 呼吸强度、丙二醛含量及多酚氧化酶活力最低;但PVDC膜在叶绿素保持及提高超氧化物歧化酶活力方面不如PE 膜。综合分析得出,鲜切西兰花贮藏0～9 d,PVDC膜保鲜效果最好;贮藏9～12 d,PE膜包装的商品性最高。     

Effects of chitosan coating on quality and shelf life of silver carp during frozen storage

The effects of chitosan coating on quality and shelf life of silver carp during frozen storage were investigated. Fish samples were treated with aqueous solution of 2% chitosan, and then stored at −3 °C for 30 days. The control and the treated fish samples were analyzed periodically for microbiological (total viable count), chemical (pH, TBA, TVB-N, K-value), and sensory characteristics. The results indicated that the effect of chitosan coating on fish samples was to retain their good quality characteristics and extend the shelf life during frozen storage, which was supported by the results of microbiological, chemical, and sensory evaluation analyses.     

Shelf life of ready to use peeled shrimps as affected by thymol essential oil and modified atmosphere packaging

In this work the influence of different packaging strategies on the shelf life of ready to use peeled shrimps was investigated. First, the effectiveness of the coating (Coat) and the active coating loaded with different concentrations of thymol (Coat-500, Coat-1000, and Coat-1500) on the quality loss of the investigated food product packaged in air was addressed; afterwards, the thymol concentration that had shown the best performance was used in combination with MAP (5% O₂; 95% CO₂). Microbial cell load of main spoilage microorganisms, pH and sensorial quality were monitored during the refrigerated storage. Results of the first step suggested that the sole coating did not affect the microbial growth. A slight antimicrobial effect was obtained when the coating was loaded with thymol and a concentration dependence was also observed. Moreover, the active coating was effective in minimizing the sensory quality loss of the investigated product, it was particularly true at the lowest thymol concentration. In the second step, the thymol concentration (1000 ppm) that showed the strike balance between microbial and sensorial quality was chosen in combination with MAP. As expected, MAP significantly affected the growth of the mesophilic bacteria. In particular, a cell load reduction of about 2 log cycle for the samples under MAP respect to that in air was obtained. Moreover, the MAP packaging inhibited the growth of the Pseudomonas spp. and hydrogen sulphide-producing bacteria. The MAP alone was not able to improve the shelf life of the uncoated samples. In fact, no significant difference between the control samples packaged in air and MAP was observed. Whilst, the use of coating under MAP condition prolonged the shelf life of about 6 days with respect to the same samples packaged in air. Moreover, when the MAP was used in combination with thymol, a further shelf life prolongation with respect to the samples packaged in air was observed. In particular, a shelf life of about 14 days for the active coating under MAP compared to the same samples in air (5 days) was obtained.     

Effects of chitosan-based coating and modified atmosphere packaging (MAP) on browning and shelf life of fresh-cut lotus root (Nelumbo nucifera Gaerth)

The present study investigated the effect of chitosan coating containing antibrowning agents and modified atmosphere packaging (MAP) on the browning and shelf life of fresh-cut lotus root stored at 4 °C for 10 days. The atmosphere in the packages was evaluated for O₂ and CO₂ concentrations. The browning on the surface of lotus root slices was prevented by chitosan-based coating and MAP treatment. L* values of coated + MAP and control samples were 68.8 and 48.9 after 8 days storage, respectively. For a^? and b^? values, samples of coated + MAP treatment had the slowest increasing trends among all the treatments. At the end of storage, the coated + MAP samples exhibited the lowest polyphenol oxidase (PPO) activity and malondialdehyde (MDA) content. Its highest overall visual quality (OVQ) scores (> 7) demonstrated that chitosan-based coating + MAP treatment could provide a better inhibitory effect on the browning and extend the shelf life of fresh-cut lotus root.Industrial relevance: Fresh-cut vegetables have drawn the attention of industry as a novel lightly processed product. Both edible coating and MAP treatment cause changes in atmosphere composition and respiration rate of lotus root slices. This combined treatment could be used to control the browning and improve the storage life of this fresh-cut vegetable. This information could be useful for the development of novel application to edible coating and MAP design for lightly processed lotus root.     

Nondestructive and Continuous Monitoring of Oxygen Levels in Modified Atmosphere Packaged Ready‐to‐Eat Mixed Salad Products Using Optical Oxygen Sensors,and Its Effects on Sensory and Microbiological Counts during Storage

The objective of this study was to determine the percentage oxygen consumption of fresh, respiring ready‐to‐eat (RTE) mixed leaf salad products (Iceberg salad leaf, Caesar salad leaf, and Italian salad leaf). These were held under different modified atmosphere packaging (MAP) conditions (5% O₂, 5% CO₂, 90% N₂ (MAPC—commercial control), 21% O₂, 5% CO₂, 74% N₂ (MAP 1), 45% O₂, 5% CO₂, 50% N₂ (MAP 2), and 60% O₂, 5% CO₂, 35% N₂ (MAP 3)) and 4 °C for up to 10 d. The quality and shelf‐life stability of all packaged salad products were evaluated using sensory, physiochemical, and microbial assessment. Oxygen levels in all MAP packs were measured on each day of analysis using optical oxygen sensors allowing for nondestructive assessment of packs. Analysis showed that with the exception of control packs, oxygen levels for all MAP treatments decreased by approximately 10% after 7 d of storage. Oxygen levels in control packs were depleted after 7 d of storage. This appears to have had no detrimental effect on either the sensory quality or shelf‐life stability of any of the salad products investigated. Additionally, the presence of higher levels of oxygen in modified atmosphere packs did not significantly improve product quality or shelf‐life stability; however, these additional levels of oxygen were freely available to fresh respiring produce if required. This study shows that the application of optical sensors in MAP packs was successful in nondestructively monitoring oxygen level, or changes in oxygen level, during refrigerated storage of RTE salad products.     

Development of antimicrobial edible coating based on modified chitosan for the improvement of strawberries shelf life

Food Science and Biotechnology - Edible antimicrobial coating produced from chitosan (CS) and its derivative was applied to improve the shelf life of fresh strawberries at 10&nbsp;°C....     

Using polysaccharide-based edible coatings to enhance quality and antioxidant properties of fresh-cut melon

The effect of alginate, pectin and gellan-based edible coatings on the shelf-life of fresh-cut ‘Piel de Sapo’ melon was investigated. Gas exchange, antioxidant properties, color, firmness, sensory quality and microbial growth of fresh-cut melon were studied during 15 days at 4 °C. Gellan, pectin and alginate coatings increased the water vapor resistance of fresh-cut melon, thus preventing dehydration. They also had an inhibitory effect on ethylene production although O₂ and CO₂ diffusion through coated melon tissue was not avoided. Calcium chloride used as a crosslinking agent helped to maintain fruit firmness. Edible coatings themselves did not improve microbiological stability of fresh-cut ‘Piel de Sapo’ melon packaged under passive modified atmosphere. Pectin or alginate could reduce the wounding stress induced in fresh-cut melon, which triggered an accumulation of total phenolic compounds and other compounds with antioxidant properties. In addition, pectin-based coating seemed to best maintain sensory attributes.     

Behavior of Listeria monocytogenes and Aeromonas spp. on fresh-cut produce packaged under equilibrium-modified atmosphere.

Storage experiments were conducted to follow the behavior of pathogens on fresh-cut vegetables (trimmed brussels sprouts, grated carrots, shredded iceberg lettuce, and shredded chicory endives) packaged under an equilibrium-modified atmosphere (EMA) (2 to 3% O2, 2 to 3% CO2, and 94 to 96% N2) and stored at 7 degrees C. As a comparison, fresh-cut vegetables were also packaged in a perforated high-barrier film (air conditions) and stored at 7 degrees C. In a first step, the shelf life of the vegetables in the two kinds of packages was determined by evaluating the microbiological quality as well as the sensorial quality (appearance, taste, and odor). In general, sensorial properties were faster in limiting the shelf life than microbiological criteria. The shelf life of the vegetables stored under an EMA was extended by 50% or more, compared with the air-stored vegetables. In a second storage experiment, the four fresh-cut vegetables were inoculated with a cocktail of psychrotrophic pathogens (Listeria monocytogenes, Aeromonas caviae [HG4]) and A. bestiarum (HG2) before packaging under an EMA and air at 7 degrees C. The inoculated pathogens were more influenced by the type of vegetable than by the type of atmosphere. No growth was detected on the brussels sprouts or on carrots (L. monocytogenes). Aeromonas spp. had a higher growth rate than L. monocytogenes on the shredded chicory endives and shredded iceberg lettuce at 7 degrees C.