气调包装对百香果贮藏品质的影响

为探讨不同气调包装材料对百香果贮藏品质的影响,以‘紫香1号’百香果为试材,对其进行活性袋包装和普通聚乙烯袋包装两种处理,包装好后封口,并于温度（25±1）℃、相对湿度70%～80%的条件下贮藏;相同成熟度未进行包装的果实于相同条件下贮藏作为对照,监测贮藏期间百香果的质量损失率、可溶性固形物与可滴定酸含量、果皮的L*、a*、b*值、果皮缺陷指数及贮藏寿命。结果表明,与对照相比,两种气调包装均减缓了果实质量损失率的上升,延缓了果皮缺陷指数及其他与百香果后熟有关的物理化学变化,能延长贮藏寿命至少6 d;采用活性包装的百香果品质保持得更好,货架期更长。     

不同包装方式下冷鲜青虾的菌群多样性分析

对青虾采用两种包装方式：托盘包装和气调包装（体积分数50% CO2＋50% N2）,在4?℃条件下贮藏6?d,测定菌落总数和挥发性盐基氮含量,确定不同包装方式下青虾的货架期;随后利用16S?rDNA扩增子测序对两种包装方式下青虾微生物多样性进行研究,比较其菌相变化,确定其变化规律。结果表明：托盘包装组和气调包装组的货架期分别为2?d和4?d;且两种包装方式下变质青虾的菌群结构有较大差异,在托盘包装方式下,优势菌群主要以不动杆菌、黄杆菌和希瓦氏菌为主,是普通低温贮藏时造成青虾腐败的主要菌群;采用气调包装后,黄杆菌和希瓦氏菌数量大大降低,假单胞菌成为主要优势菌群;体积分数50%?CO2＋50%?N2气调包装能抑制托盘包装时优势腐败菌的增殖,从而延长货架期;而假单胞菌有较强的耐受力,成为新的优势腐败菌。研究结果为保障青虾的质量安全提供了理论依据。     

Active Banana Flour Nanocomposite Films Incorporated with Garlic Essential Oil as Multifunctional Packaging Material for Food Application

Active plasticized banana flour nanocomposite film (APBNF) incorporated with a different garlic essential oil (GO) content was formed using a solution casting to determine the film properties prior to the investigation of its effectiveness to preserve the roasted peanut quality. The GO concentration was positively correlated with the ultraviolet (UV) light barrier property and antioxidant activity indicating the ability to protect the packed food product from lipid oxidation. Additionally, incorporation of 1 mg/mL GO into APBNF showed the highest antioxidant activity and completely inhibited the growth of Aspergillus flavus. Fourier-transform infrared spectroscopy confirmed the functional group interactions between the film matrix and GO which act as an antioxidant and antimicrobial agent. Thus, APBNF incorporated with 1 mg/mL GO as an active packaging to preserve the quality of roasted peanuts was investigated comparing with a commercial plastic packaging of polyethylene terephthalate/low-density polyethylene (PET/LDPE; PET). The shelf life estimation of roasted peanuts packed in both packaging materials (APBNF and PET) based on the peroxide value (PV) was similar at high storage temperature (45 °C). Therefore, APBNF shows a multifunctional primary food packaging to maintain the quality of roasted peanuts or oily food products.     

Effectiveness of antimicrobial coated oriented polypropylene/polyethylene films in sprout packaging

This study focused on the effect of antimicrobial incorporated soy protein isolate (SPI) coated oriented polypropylene/polyethylene (OPP/PE) packaging on extended shelf life of fresh sprouts. To develop antimicrobial SPI-coated packages, the minimum inhibitory and bactericidal concentrations of antimicrobial (allyl isothiocyanate, trans-cinnamaldehyde, garlic oil, and rosemary oil) and film properties of antimicrobial incorporated SPI films were investigated. Different concentrations (0.6–1.2%, v/v) of the SPI incorporated antimicrobial compounds were coated onto the OPP/PE film and heat-sealed. Packages containing sprouts (alfalfa, broccoli, and radish) were stored at 10 °C for 5 days. Significant reduction of the total microbial count of sprouts was observed in treated samples. Allyl isothiocyanate was the most effective antimicrobial compound, followed by garlic oil and trans-cinnamaldehyde.     

低频电场冰温保鲜对虾的水分迁移规律及品质变化的影响

为探明低频电场延长冰温保鲜对虾货架期的可行性。在冰温基础上施加低频电场（LFEF+冰温）保鲜对虾,监测贮藏期间对虾的菌落总数和总挥发性盐基氮（TVB-N）含量变化,分析微观结构变化,通过低场核磁共振（LF-NMR）技术探究虾肉和虾头的水分迁移和变化规律,并与常规冰温保鲜作对照。结果表明:贮藏第9 d,LFEF+冰温组的菌落总数和TVB-N含量开始表现出显著低于对照组的趋势（P<0.05）;第12 d后,LFEF+冰温组的菌落总数比对照组低一个数量级;其TVB-N含量在第11 d比对照组显著低36%（P<0.05）,货架期可达13 d以上。相比对照组的松散结构,LFEF+冰温组的虾肉微观结构变化程度明显较小。LF-NMR结果表明,低频电场从第7 d开始明显抑制冰温保鲜对虾虾头部位不易流动水向自由水的迁移,MRI成像可见水分扩散较慢。虾肉的腐败速率则低于虾头,LFEF+冰温组虾肉15 d内未出现明显的水分迁移。低频电场有利于延缓冰温保鲜期间对虾的腐败,延长货架期3~5 d。     

Effect of Chitosan Film Coating Combined with Orange Peel Essential Oil on the Shelf Life of Deepwater Pink Shrimp

In this study, effect of chitosan films combined with orange (Citrus sinensis (L.) Osbeck) peel essential oil on the shelf life of deepwater pink shrimp (Parapenaeus longirostris Lucas 1846) was aimed. Chitosan (CH) and 2% orange peel essential oil (OPEO) combinated chitosan (CH+OPEO) were used for preparing film forming solution. Thickness and microstructure of the films, nutritional composition, sensory and melanosis evaluation, chemical, physical, and microbiological analyses were performed periodically and shelf-life was performed during the storage period of 15 days. The combination of chitosan film with OPEO was effective in prolonging the shelf life of fresh shrimps to 15 days (CH+OPEO), whereas the only chitosan-coated group had a shelf life of 10 days (CH) and the samples packaged without chitosan film had a shelf life of 7 days (control). The results of the study suggested that edible chitosan coatings together with OPEO preserved the shrimps and maintained the shelf life throughout the refrigerated storage period.     

Production and characterisation of skate skin gelatin films incorporated with thyme essential oil and their application in chicken tenderloin packaging

In this study, skate skin gelatin (SSG) was used as a new biodegradable film source and a SSG film was prepared. In addition, thyme essential oil (TEO) was incorporated in the SSG film as an antimicrobial agent for the preparation of an antimicrobial film. The tensile strength (TS) of the film decreased, whereas elongation at break (E) increased by the addition of TEO. The SSG film containing TEO showed increased antimicrobial activity against Listeria monocytogenes and Escherichia coli O157:H7 as TEO concentration increased. To apply the SSG film to food packaging, chicken tenderloin samples were wrapped with the film containing 1% TEO. The packaging of chicken tenderloin with the TEO‐containing SSG film inhibited the growth of L. monocytogenes and E. coli O157:H7 compared to the control during storage. Therefore, the SSG film with added TEO has potential as active food packaging to extend the shelf life of chicken tenderloin.     

Extension of the shelf life of prawns (Penaeus japonicus) by vacuum packaging and high-pressure treatment

The present study has investigated the application of high pressures (200 and 400 MPa) in chilled prawn tails, both conventionally stored (air) and vacuum packaged. Vacuum packaging and high-pressure treatment did extend the shelf life of the prawn samples, although it did affect muscle color very slightly, giving it a whiter appearance. The viable shelf life of 1 week for the air-stored samples was extended to 21 days in the vacuum-packed samples, 28 days in the samples treated at 200 MPa, and 35 days in the samples pressurized at 400 MPa. Vacuum packaging checked the onset of blackening, whereas high-pressure treatment aggravated the problem. From a microbiological point of view, batches conventionally stored reached about 6 log CFU/g or even higher at 14 days. Similar figures were reached in total number of bacteria in vacuum-packed samples and in pressurized at 200-MPa samples at 21 days. When samples were pressurized at 400 MPa, total numbers of bacteria were below 5.5 log CFU/g at 35 days of storage. Consequently, a combination of vacuum packaging and high-pressure treatment would appear to be beneficial in prolonging freshness and preventing spotting.     

Effect of processing and packaging conditions on quality of refrigerated potato strips

Abstract: Although sulfiting agents are commonly used in the fresh‐cut potato industry, concerns about further regulatory restrictions on sulfite use and consumer fear of sulfite‐treated foods have lead to increased research in alternative processing methods. The objective of this study was to determine processing and packaging techniques to achieve a safe and high‐quality potato strips with a 4 wk minimum refrigerated shelf life. Potato strips were 1st blanched at low temperature (60 °C) in 0.5% CaCl₂ solution for 20 min and then 2nd blanched at high temperature (approximately 98 °C) in water for 5 min. Blanched strips were packaged in a near‐aseptic environment or treated in‐package with gaseous ozone, sodium metabisulfite (SM) solution, or FIT Fruit and Vegetable Wash? (Procter and Gamble Co., Cincinnati, Ohio, U.S.A.) and then stored at 7 ± 1 °C for 28 d. No significant difference was observed in lightness of near‐aseptically packaged fries, FIT‐treated fries, and frozen fries; however, less color difference was determined in near‐aseptically packaged fries and FIT‐treated fries compared to frozen fries. Gaseous ozone treatment decreased color quality of potato strips, significantly. The highest after‐frying peak force was observed in FIT‐treated strips. There was no significant difference in oil absorption of refrigerated and unprocessed strips. These results indicate that either near‐aseptic packaging or in‐package FIT treatment are the better alternatives for blanched potato strips to extend shelf life and maintain quality. Practical Application: In this study, several processing conditions and packaging methods were evaluated to improve quality and extend shelf life of refrigerated potato strips. Results indicate that the combination of 2‐step blanching and near‐aseptic packaging was an effective nonchemical processing method, giving 28 d refrigerated shelf life. Similarly, FIT Fruit and Vegetable Wash? proved to be an effective chemical alternative to sulfites and avoids the allergen concern.     

Quality of giant freshwater prawn (Macrobrachium rosenbergii) during the storage at −18°C as affected by different methods of freezing

This study investigated the effects of liquid nitrogen quick-freezing, ?35°C air-blast freezing, and ?18°C refrigerator direct-freezing on quality retention of frozen giant freshwater prawns using various indicators: microscopic structure, physicochemical, texture, and color properties. The results showed that the shelf lives of prawns treated with liquid nitrogen quick-freezing, ?35°C air-blast freezing, and ?18°C refrigerator direct-freezing were about 20, 12, and 8 weeks, respectively, in terms of total volatile basic nitrogen content and K-value. Meanwhile, liquid nitrogen quick-freezing could effectively improve texture property of frozen giant freshwater prawn. These findings confirm that liquid nitrogen quick-freezing is a promising method to extend the shelf life of frozen prawns.     

The microbial safety of strawberry and raspberry fruits packaged in high-oxygen and equilibrium-modified atmospheres compared to air storage

Microbial safety of strawberry and raspberry fruits was assessed after shelf‐life extension by two new packaging systems, high‐oxygen atmospheres (HOA) and equilibrium‐modified atmospheres (EMA), in combination with an ethylene absorbing film. Both fruits had a shelf‐life of 3 days at 7 °C when macroperforated films were used. Strawberry fruits were acceptable for 5 days in both packages, raspberries had a shelf‐life of 7 and 5 days when using EMA and HOA respectively. Escherichia coli, Salmonella spp. and Listeria monocytogenes were artificially inoculated onto packaged fruits. All were able to survive on packaged fruits stored at 7 °C. Raspberries showed an enhanced inactivation of Salmonella during storage time in both types of packaging. Growth of L. monocytogenes was observed on the calyx of strawberries after the end of the established shelf‐life. Generally, increasing the shelf‐life of the fruits with EMA and HOA did not give an increased microbial risk.     

不同温度和包装方式对荔枝保鲜品质的影响

为掌握温度和包装对荔枝货架期的影响,本试验以“淮枝”荔枝为试验材料,以裸露的荔枝和由开孔袋包装的荔枝,分别处于常温货架和低温货架,研究不同因素对荔枝质量损失率、褐变指数、好果率、色差、可溶性固形物含量和可滴定酸含量的影响。试验表明：低温货架和包装都能延长荔枝货架期,各品质指标整体衰变速度从快到慢依次为：常温裸露、常温包装、低温裸露、低温包装。对荔枝货架期影响因素中,温度占主要影响作用,低温货架有效的降低了荔枝各指标的变质速度;开孔聚乙烯薄膜包装也能降低荔枝品质的衰变,该影响小于货架温度的影响。常温货架无包装的荔枝好果率在30 h变为0,低温包装荔枝的好果率在60 h仍保有9.20%。与常温货架荔枝裸露的销售方式对比,采用低温货架并由开孔聚乙烯薄膜包装可以使荔枝货架期延长一倍以上。该文为荔枝货架期保鲜研究提供了参考。     

Influence of different packaging systems on fresh-cut zucchini (Cucurbita pepo)

In this work different packaging strategies aimed to prolong the shelf life of minimally processed zucchini are presented. In particular, two different cultivars (Sofia and Diamante) were tested. The sliced zucchini were packaged in oriented polypropylene-based (OPP) bag and into a bio-polymeric film (COEX) under passive and active MAP. The investigated produce was stored at 5 °C for approximately 9 days. Headspace gas concentrations, pH, mass loss, sensory quality and viable cell load of main spoilage microorganisms were monitored for the entire observation period. In order to determine the respiration activity, O₂ and CO₂ concentrations were monitored not only in OPP and COEX packages but also in the headspace of an aluminum-based package. Results suggested that for Diamante cultivar OPP film under active and passive MAP showed slightly better performances in prolonging the shelf life, compared to COEX film; instead, for Sofia cultivar better results were obtained with OPP film only under active MAP conditions.Industrial relevanceThis paper suggests an effective packaging solution to delay the quality decay kinetic of two cultivars of fresh-cut zucchini. Due to changes in consumer attitudes, the proposed mild strategies to prolong the shelf life of ready-to-cook products could really gain widespread acceptance by industry of the minimally processed food sector. Due to great attention to the environmental pollution a biodegradable packaging system was also studied and compared to the common polypropylene-based film, even though the characteristics of this specific produce could not suggest the substitution with traditionally used plastic materials with eco-friendly polymers.     

QUALITY CHANGES IN FRESH‐CUT SPINACH (SPINACIA OLERACEA) UNDER MODIFIED ATMOSPHERES WITH PERFORATIONS

ABSTRACT

Fresh‐cut spinach leaves were stored for 4 days at 15C and 75% relative humidity under modified atmosphere packaging to assess the impact of differential in‐pack gas atmospheres generated through different packaging films and variable in‐pack weight on the quality of stored produce. After 4 days of storage, retention of chlorophyll, β‐carotene and ascorbic acid was better in low‐density polyethylene (LDPE) packages than in polypropylene (PP) packages. LDPE film‐packaged samples had higher phenolic content than PP film‐packaged samples. Low in‐pack O₂ (1–2 kPa) along with the buildup of CO₂ (8–10 kPa) seems to have enhanced the retention of antioxidant components, i.e., β‐carotene and ascorbic acid, in LDPE packages. This helped in chlorophyll retention and also prevented formation of oxidation compounds of phenols that otherwise caused browning of cut surfaces. Thus, O₂ and CO₂ permeability of packaging film or in‐pack weight of produce might be such that equilibrated O₂ partial pressures remain near to 1–2 kPa so as to affect a beneficial increase in the phenolic content along with concomitant retention of chlorophyll.

PRACTICAL APPLICATIONS

Fresh‐cut spinach leaves have received an enormous demand due to their utility in various traditional Indian preparations. Shelf life and quality of fresh‐cut produce may be greatly reduced due to high rates of respiration. Traditional packaging and handling techniques reduce the shelf life and sensory quality of fresh‐cut spinach. Temperature control and atmospheric modifications help to maintain produce quality by reducing respiration rate and enhance shelf life by minimizing the adverse effects of cutting. This research focused on evaluation of respiratory behavior of fresh‐cut spinach leaves at a temperature commonly encountered during transportation and retail distribution, i.e., 15C, and the effect of different polymeric films and in‐pack weights on produce quality. The results of the study suggest that packaging of fresh‐cut spinach in polymeric film packages could maintain the sensory quality and reduce degradation of various physicochemical constituents. Utilization of the results for proper design of modified atmosphere packages for this highly perishable produce can prove to be extremely beneficial for safe storage and transportation to urban retail markets.     

Evaluation of PLA nanocomposite films on physicochemical and microbiological properties of refrigerated cottage cheese

A novel antimicrobial packaging system was prepared by incorporating TiO₂ or Ag nanoparticles into poly(lactic acid) (PLA) matrix. The effect of PLA, PLA/TiO₂, and PLA/TiO₂ + Ag film on the physicochemical and microbiological properties of Yunnan cottage cheese stored at 5 ± 1 °C for 25 days was investigated. The low density polyethylene (LDPE) film was used as the control. The weight loss, pH value, lactic acid bacteria count (LAB), texture, sensory quality, and antimicrobial activity were determined. Cheeses packed by PLA/TiO₂ and PLA/TiO₂+Ag film provided better retention in pH value, LAB, sensory quality, and antimicrobial activity compared with those packed by PLA and LDPE film. Migration of Ti and Ag nanoparticles was lower than the limit of 10 mg/kg as defined by EFSA for food contact materials. The results indicated that the incorporation of TiO₂ or Ag nanoparticles into PLA matrix could maintain cheese quality and prolong its shelf life to 25 days.

Practical applications

Yunnan cottage cheese is one of the most popular cheeses in China. However, the shelf life of unpacked Yunnan cottage cheese is only 5–7 days under refrigerated condition. PLA film incorporated with antimicrobial TiO₂ or Ag nanoparticles has great potential to prolong cheese shelf life. The novel packaging material may be an effective alternative for cheese preservation.     

Active Packaging of Cardboard to Extend the Shelf Life of Tomatoes

In order to extend the shelf life of fresh tomatoes using biodegradable materials, an active microcorrugated cardboard tray package was tested for use with fresh Cherry tomatoes (Lycopersicon esculentum var. cerasiforme). Active packaging characteristics were achieved by coating the interior surface of the cardboard tray with polylactic acid (PLA; 3% w/v) and, after filling with tomatoes, the tray was wrapped with a low-density polyethylene (LDPE) film of 70 or 20 μm thickness and hermetically heat sealed. Uncoated trays were used as control. The trays of tomatoes were stored at 20?±?0.5 °C and 55?±?2% relative humidity, for 30 days, and the ethylene concentration in the package atmosphere was measured periodically as an indicator of ripeness. The following fruit quality parameters were also studied: weight loss, surface colour, microbial count, firmness, soluble solids and pH. It was demonstrated that the capacity of PLA to adsorb ethylene and water vapour and the thickness of the LDPE film were decisive for controlling the ethylene concentration of the package atmosphere and for preventing condensation of water vapour on the fruit and film. The active packaging configuration and storage conditions used preserved fruit quality for a month, thus extending the useful life of the tomatoes and saving refrigeration costs.     

Changes in Fatty Acids and Sensory Quality of Fresh Water Prawn (Macrobrachium rosenbergii) Stored Under Frozen Conditions

The effects of frozen storage and packaging methods on the oxidation of fatty acids and rancidity development in fresh-water prawn Macrobrachium rosenbergii were studied. The lipids of these fresh prawns contained 23% saturated, 46% monounsaturated, and 31% polyunsaturated fatty acids. The fatty acids, especially the unsaturated ones decreased during frozen storage for 6 months at -18°C, regardless of the packaging procedure employed. No objectionable rancid flavor was detected in these prawns during the 6-month frozen storage study.     

Gas Permeability and Thermal Behavior of Polypropylene Films Used for Packaging Minimally Processed Fresh‐Cut Potatoes: A Case Study

Abstract: This work reports an experimental study on the permeability and thermal behavior of commercial polypropylene (PP) film used for fresh‐cut potatoes packaging. The permeability was tested using oxygen, carbon dioxide, nitrogen, mix of these 3 gases, normally used for modified atmosphere packaging (MAP) and Air, to understand if it would be possible to extend the shelf life of this food product designed for the catering field in respect to the packaging behavior. The temperature influence on permeability data, from 5 to 40 °C, was analyzed, before and after 4, 8, 12, 15, and 20 d of food contact, pointing out the dependence between temperature and gas transmission rate (GTR), solubility (S), diffusion coefficient (D), and time lag (t_L) parameters. The activation energies (E) of the permeation process were determined with the different gases used in the experiments. The thermal behavior of PP film was studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) to well understand its thermal stability. Fourier transformed‐infrared with attenuated total reflectance (FT‐IR/ATR) spectroscopy was also performed in order to study the influence of the food contact on the chemical characteristics of the polymer film. The results obtained were discussed and compared each other. Studied samples showed, for all investigated gases, an increase of gas permeability and S values at higher temperature. Heat resistance classification among the sample as it is and stored in modified atmospheres was made. Finally all performed experiments have showed good polymer stability for the shelf‐life storage potatoes under study. Practical Application: Study of packaging material was performed in a range of temperature, which can simulate the service condition to assess the suitability of a commercial polymer film for modified atmosphere packaging of fresh‐cut potatoes minimally processed designed for catering purpose.     

超高压灭菌保存即食鲜虾的研究

以对虾为试验原料,采用不同压力和保压时间处理鲜虾仁,研究了超高压的杀菌效果以及对产品质构的影响;结果表明,压力是影响杀菌效果的主要因素。当压力为500MPa,连续加压2次,每次保压时间为15min时,具有最佳灭菌效果。与沸水中灭菌和高温灭菌相比,超高压灭菌对对虾质构的影响最小,能较好地保持虾仁的硬度、咀嚼性和弹性;真空包装能有效延长的货架期。因此,采用真空包装和超高压灭菌处理是即食虾产品的最佳保存工艺。