Gelatin/pectin-based film incorporated with essential oils: Functional characteristics and shelf life extension of tilapia fillets under refrigeration

Fish gelatin-pectin (Gel_Ext/Pec) composite films incorporated with Mentha pulegium essential oil (MEO) and Lavandula angustifolia essential oil (LEO) at two concentrations (0.5% and 1.5%) were developed and their physicochemical, mechanical, and antimicrobial properties were determined. Gel_Ext/Pec-based film incorporated with 1.5% MEO (Gel_Ext/Pec + 1.5% MEO) showed the highest antimicrobial activity against all bacterial strains tested. Incorporation of essential oils decreased significantly the tensile strength of all the films investigated. The film showing the best functional and antimicrobial properties (Gel_ext/Pec + 1.5% MEO) was used to prolong the shelf life of tilapia fillets under refrigeration. Control (unwrapped) and wrapped fillets were analyzed every 3 days in terms of microbiological (total viable count (TVC), psychrotrophic bacteria count (PC), lactic acid bacteria (LAB) and Enterobacteriaceae (ENT), and physicochemical parameters (total volatile base nitrogen [TVB-N] and pH). Gel_ext/Pec + 1.5% MEO antimicrobial film retarded significantly (p < .05) the growth of TVC, LAB, PC, and ENT, throughout 12 days of storage compared with the control. Gel_ext/Pec + 1.5% MEO could be considered as an effective packaging to maintain the quality and extend the shelf life of tilapia fillets under refrigeration.     

Bio-based nanocomposite coating to preserve quality of Fior di latte cheese

The aim of this study was to evaluate the effects of a bio-based coating containing silver-montmorillonite nanoparticles combined with modified-atmosphere packaging (MAP) on microbial and sensory quality decay of Fior di latte cheese. Different concentrations of silver nanoparticles (0.25, 0.50, and 1.00 mg/mL) were dispersed in a sodium alginic acid solution (8% wt/vol) before coating the cheese. Modified-atmosphere packaging was made up of 30% CO₂, 5% O₂, and 65% N₂. The combination of silver-based nanocomposite coating and MAP enhanced Fior di latte cheese shelf life. In particular, product stored in the traditional packaging showed a shelf life of about 3 d, whereas coated cheese stored under MAP reached a shelf life of more than 5 d, regardless of the concentration of silver nanoparticles. The synergistic effects between antimicrobial nanoparticles and initial headspace conditions in the package could allow diffusion of dairy products beyond the local area.     

Postharvest Quality of Fresh-Cut Carrots Packaged in Plastic Films Containing Silver Nanoparticles

Active food packaging containing antimicrobial additive goes beyond traditional functions of packaging, once it can extend food shelf life maintaining its quality, safety and reducing postharvest losses by controlling food spoilage. Among several antimicrobial additives employed in polymeric films for packaging, metallic nanoparticles outstand due to its facility for synthesis, low-cost of production, and intense antimicrobial properties. In this work, extruded plain films of low-density polyethylene (LDPE) containing silver nanoparticles (AgNPs) embedded in SiO₂ and TiO₂ carriers (namely MS and MT, respectively) were produced and used as active packaging for maintaining the physicochemical and microbiological quality of carrots (Daucus Carota L. cv. Brasília). The neat (LDPE) and composite films containing MS and MT were characterized by scanning electron microscopy and permeability to oxygen and used for packaging fresh-cut sliced carrots stored at 10 °C for 10 days. After the storage time, the physicochemical properties of carrots were characterized, while the antimicrobial properties of films and AgNP migration were investigated. Our results revealed that both MT and MS packages showed antimicrobial activity even for films containing low concentration of AgNP. In addition, AgNP antimicrobial activity demonstrated to be carrier-dependent, once MT-LDPE showed improved performance compared to MS-LDPE. Regarding the physicochemical properties of packaged carrot, lower soluble solids and weight loss and higher levels of ascorbic acid were observed for carrots packaged with MT-LDPE films (compared to MS-LDPE), leading to a better postharvest quality conservation. Such differences observed in physicochemical properties of carrots are related to the distinct antimicrobial and film permeability properties for each composite film. In addition, under the conditions employed in this study, AgNP migration from the packages to fresh-cut carrot was not observed, which is highly desirable for food packaging safety, indicating the potential of such active packages for food preservation application.     

Surface coating of silver nanoparticles on polyethylene for fabrication of antimicrobial milk packaging films

In this study, antimicrobial packaging films were prepared by coating silver (Ag) nanoparticles onto the surface of low density polyethylene (LDPE) films modified by corona air plasma. The possibility of these films for use in the packaging of milk was studied. The influence of input power of the corona discharge treatment on the surface modification and performance of the fabricated Ag/LDPE nanocomposite films was also investigated. The prepared antimicrobial packaging films showed promising antimicrobial efficiency against micro‐organisms that are present in milk and were able to increase the microbial shelf life of the milk. Packages fabricated at corona input powers of 210, 500 and 800 W reached the maximum limit after 5, 8 and 14 days (respectively).     

Lysozyme/EDTA disodium salt and modified-atmosphere packaging to prolong the shelf life of burrata cheese

To prolong the shelf life of burrata cheese, we evaluated the effects of lysozyme and EDTA disodium salt (Na₂-EDTA) with or without modified-atmosphere packaging (MAP) conditions. In particular, 3 concentrations of enzyme were combined with packaging in air and under MAP (95:5 CO₂:N₂). The decline in quality of burrata cheese stored at 8°C was assessed by monitoring microbiological and sensory quality, in addition to pH and headspace composition. The combination of lysozyme/Na₂-EDTA and MAP prolonged cheese shelf life, especially at the highest lysozyme concentration. In particular, the tested strategy was effective against microbial spoilage phenomena that appeared to be the quality factor that determine product unacceptability.     

Evaluation of biodegradable film packaging to improve the shelf-life of Boletus edulis wild edible mushrooms

The objective of this work was to evaluate the effect of poly(lactic acid) (PLA) based biodegradable film packaging combining 0.5% nisin antimicrobial polypeptide on the physicochemical and microbial quality of Boletus edulis wild edible mushrooms stored at 4 ± 1 °C. The experiment was set up by packaging mushrooms with extruded PLA films containing 0, 7.5, and 15 wt.% triethyl citrate plasticizer. The low-density polyethylene (LDPE) film was used as the control. Mushrooms stored in PLA films containing 7.5 and 15 wt.% plasticizer provided better retention of quality characteristics and received higher sensory ratings compared to mushrooms stored in pure PLA film and LDPE film. Samples with these two treatments underwent minimal changes in texture, PPO activity, total bacteria count, and sensory attributes. Results suggest that nisin in combination with plasticized PLA film has the potential to maintain B. edulis wild edible mushroom quality and extend its postharvest life to 18 days.Industrial relevanceB. edulis is one of the most commercialized mushrooms worldwide. However, as with all fresh mushrooms, there are severe preservation problems. Extruded PLA films containing triethyl citrate plasticizer plus antimicrobial agent nisin proved to be a suitable technology for mushroom conservation. This material exhibits an environmental-friendliness potential and a high versatility in food packaging.     

GEO添加量对PLA/GEO复合膜性能及双孢蘑菇保鲜效果的影响

本文研究了不同浓度（0%、5%、7.5%、10%和12.5%）的葡萄柚精油（GEO）对聚乳酸(PLA)/葡萄柚精油复合膜的热性能,结构性能,机械性能,气体阻隔性能和抗菌性能等方面的影响。GEO通过减少聚合物链段的分子间作用力,从而改善复合膜的柔韧性,对复合膜起到一定的增塑作用。GEO的添加降低了PLA相的结晶性。随着GEO浓度的增加,复合膜的水蒸汽阻隔性能显著降低。但是,复合膜的抗菌活性因GEO的加入得以提高。将聚乳酸/葡萄柚精油复合膜应用于双孢蘑菇保鲜。结果表明,聚乳酸/葡萄柚精油复合膜与纯聚乳酸膜、低密度聚乙烯膜相比较,更能有效地保持蘑菇的硬度,阻止微生物生长,维持较好的总体接受度。因此,聚乳酸/葡萄柚精油复合膜可作为一种有效的包装材料,用于延长双孢蘑菇的货架期。     

Addition of Carbon Dioxide to Dairy Products to Improve Quality: A Comprehensive Review

ABSTRACT: Changes in distribution patterns and demand for increased food quality have resulted in a desire to improve the shelf life of nonsterile dairy products. Refrigerated shelf life extension typically requires, at a minimum, reductions in the growth rate of spoilage microorganisms and subsequent product deterioration. Reducing initial bacterial loads, increasing pasteurization regimes, and reducing postprocessing contamination have all been employed with measured success. The use of antimicrobial additives has been discouraged primarily due to labeling requirements and perceived toxicity risks. Carbon dioxide (CO₂) is a naturally occurring milk component and inhibitory toward select dairy spoilage microorganisms; however, the precise mechanism is not fully understood. CO₂ addition through modified atmosphere packaging or direct injection as a cost‐effective shelf life extension strategy is used commercially worldwide for some dairy products and is being considered for others as well. New CO₂ technologies are being developed for improvements in the shelf life, quality, and yield of a diversity of dairy products, including raw and pasteurized milk, cheeses, cottage cheese, yogurt, and fermented dairy beverages. Here we present a comprehensive review of past and present research related to quality improvement of such dairy products using CO₂.     

Agar hydrogel with silver nanoparticles to prolong the shelf life of Fior di Latte cheese

The objective of this work was to evaluate the effectiveness of an antimicrobial packaging system containing active nanoparticles on the quality deterioration of Fior di Latte cheese. To this aim, 3 concentrations of silver montmorillonite embedded in agar were used. The cell loads of spoilage and useful microorganisms were monitored during a refrigerated storage period. Moreover, cheese sensory quality (i.e., odor, color, consistency, and overall quality) was evaluated by means of a panel test. Results showed that the active packaging system markedly increased the shelf life of Fior di Latte cheese, due to the ability of silver cations to control microbial proliferation, without affecting the functional dairy microbiota and the sensory characteristics of the product. The active packaging system developed in this work could be used to prolong the shelf life of Fior di Latte and boost its distribution beyond local market borders.     

Modified Atmosphere Packaging to Maintain Direct-Set Cottage Cheese Quality

Direct-set cottage cheese packaged in barrier containers was flushed with 100% CO₂ 75% CO₂:25% N₂, 100% N_2, or air, and stored at 4°C for 28 days. Quality was assessed by sensory, microbiological, and chemical tests. No change was observed in headspace gas composition during storage. Psychrotrophic and lactic acid bacteria counts increased for air-treated samples, but counts for cottage cheese packaged under modified atmospheres remained unchanged. Product discoloration was not observed. Acidity increased over storage life, but lactic acid did not contribute towards increased acidity. Sensory characteristics of cottage cheese packaged under modified atmospheres remained satisfactory after 28 days, with 100% CO₂ best.     

真空镀银PET包装薄膜的研究

通过真空镀膜技术将Ag蒸镀在PET薄膜上,然后用于鲜牛肉包装,以此延长鲜牛肉的货架寿命。本文讨论了经该薄膜包装储存一段时间后的鲜牛肉挥发性盐基氮(TVB-N)的变化,研究了该抗菌薄膜的抗菌效果,并用气相色谱测(GC)测定其H2S释放量,运用原子吸收光谱(AAS)测定该镀Ag材料的Ag含量。结果表明:经这种方法包装后的鲜牛肉的挥发性盐基氮(TVB-N)以及H2S释放量随着镀Ag量增加明显下降。该抗菌薄膜的杀菌率达到99.8%。     

Methods to extend the shelf‐life of cottage cheese – a review

Under typical refrigeration conditions (4–7 °C), unopened fresh cottage cheese only lasts for approximately 3 weeks unless preservatives are added. The spoilage of cottage cheese during storage is primarily due to the growth of Gram‐negative psychrotrophic bacteria, yeasts and moulds. To extend its shelf‐life, along with a strict sanitation practice throughout the manufacturing process, an appropriate preservation approach is generally applied. Many methods to preserve cottage cheese have been reported. These can be classified into three categories, namely food‐grade chemicals, heat treatment and modified atmosphere packaging. In this review, factors responsible for the spoilage of cottage cheese during storage and the methods to extend its shelf‐life are discussed.     

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.     

Agar-immobilized basil–lactic acid bacteria bioproducts as goat milk taste-masking agents and natural preservatives for the production of unripened goat cheese

Goat milk cheeses have become popular recently; however, many consumers do not choose these products because they have specific sensory properties that are not acceptable to all consumers and the shelf life of the cheese is short. The concept of this work was to increase overall acceptability and shelf life of unripened goat milk cheese by using Ocimum basilicum and lactic acid bacteria (Lactobacillus plantarum LUHS135, Lactobacillus paracasei LUHS244, Pediococcus pentosaceus LUHS100, Pediococcus acidilactici LUHS29, and Lactobacillus brevis LUHS140) bioproducts (basil-LAB) immobilized in agar. A basil-LAB bioproduct could be a promising multifunctional ingredient for cheese manufacturing because it has a low pH, high LAB count, and high total phenolic compound content (after fermentation pH decreased by 25.4%, LAB count averaged 7.2 log₁₀ cfu/g, and total phenolic compound content increased by 30.9%). Use of different LAB in the preparation of basil-LAB bioproducts had a significant influence on cheese pH and hardness, and compared with cheese samples prepared with nonfermented basil, cheese samples prepared with basil-LAB bioproducts had, on average, higher pH (by 2.6%) and lower hardness (by 36.0%), similar to the control cheese (without basil). Overall acceptability of cheese was significantly influenced by the basil-LAB bioproduct immobilization process; in all cases, cheese samples prepared with fermented and immobilized basil-LAB bioproduct had better acceptability (5 points). After 120 h of storage, cheese samples prepared with basil-LAB bioproducts fermented with LUHS135, LUHS244 and LUHS140, no enterobacteria were found, and we detected strong negative and moderate negative correlations, respectively, of LAB count with enterobacteria count and yeast/mold count (r = ?0.7939 and r = ?0.4495, respectively). Finally, immobilization increased LAB viability in fresh goat milk cheese, which led to a reduction in enterobacteria and mold/yeast contamination during storage and an increase in overall acceptability compared with nonimmobilized basil-LAB. Therefore, basil-LAB bioproducts fermented with LUHS135, LUHS244, and LUHS140 strains can be recommended for preparing fresh goat milk cheese with extended shelf life and high acceptability.     

聚乳酸薄膜对西兰花的保鲜效果分析

用聚乳酸（polylactic acid,PLA）薄膜包装西兰花,以聚乙烯（polyethylene,PE）薄膜包装和无膜包装为对照组,在（20±3）℃条件下对西兰花的相关指标进行定期测定,研究PLA薄膜对西兰花的保鲜效果。结果表明：在PLA薄膜、PE薄膜和无膜包装贮藏过程中,西兰花的VC、叶绿素含量均呈下降趋势,且前者含量明显高于后两者,而相对电导率、过氧化物酶活性均呈上升趋势,前者明显低于后两者。可见,PLA薄膜包装处理对常温条件下的西兰花有明显的保鲜效果,能有效地延长西兰花的常温货架期。     

Evaluation of nanocomposite packaging containing Ag and ZnO on shelf life of fresh orange juice

Nanocomposite LDPE films containing Ag and ZnO nanoparticles were prepared by melt mixing in a twin-screw extruder. Packages prepared from the films were then filled with fresh orange juice and stored at 4 °C. Microbial stability, ascorbic acid (AA) content, browning index, color value, and sensory attributes of them were evaluated after 7, 28, and 56 days of storage. Packages containing the nanomaterials, expect 1% nano-ZnO, kept the microbial load of fresh juice below the limit of microbial shelf life (6 log cfu/ml) up to 28 days The least degradation of AA (80.50 mg/100 g), development of brown pigments (OD = 0.23) and losing of color (∆E = 6.0) were observed in pouches containing 0.25% nano-ZnO, after the same time. Sensory attributes were also ranked highest for the juice thus packed in the recent packages after 28 days (p < 0.05). Packages containing nanosilver increased shelf life of fresh juice although part of its sensory attributes were lost.

Industrial relevance

Compared with pure packaging materials, antimicrobial nanocomposite packages containing Ag and ZnO as an alternative non-thermal technology can extend the shelf life of fresh orange juice up to 28 days. However, a certain concentration of nano-ZnO in the packages showed less adverse effects on sensory characteristics.     

Chemical and sensory changes of different dairy products during storage in packages containing nanocrystallised TiO2

The chemical changes of three types of cheese, yoghurt and kefir were evaluated during storage in packages containing TiO₂ with two different compositions of the mixed anatase–rutile phase. The influence of TiO₂ packaging during storage on titratable acidity and fat content and on the external aspect was investigated. Fourier Transformed Infrared Spectroscopy (FTIR) analyses were performed to establish whether the TiO₂ penetrated the food during storage. The results showed that the TiO₂ nanoparticles deposited on polyethylene surface significantly decreased acidity and fat content of the investigated cheese and yoghurt types. During storage in TiO₂ nanopackages, the change in chemical parameters is accentuated as the content of rutile grows from 2.8% to 6.9%. The sensory evaluation revealed that the dairy products stored for 11 days in TiO₂ nanopackages present similar colour, texture and flavour with that of the references; the samples stored in polyethylene film were found to be unacceptable.     

Quality changes in semi-hard cheese packaged in a poly(lactic acid) material

A study was performed in order to evaluate the influence of barrier properties of a poly(lactic acid) (PLA) relative to an amorphous poly(ethylene terephthalate)/polyethylene (APET/PE) packaging material on quality of Danbo cheese during light exposure and storage in the dark. Results showed that moisture loss from cheeses packaged in PLA was approximately 10 times higher than from the reference packages, but dry surface spots were not observed before 56 days of storage in the PLA packages. Secondary lipid oxidation products were primarily developed when both oxygen and light were present. During light exposure, lipid oxidation of cheeses packaged in PLA was rather limited for the first 56 days of storage, whereas lipid oxidation was almost negligible when the cheeses were protected from light during the 84 days of shelf life. The results indicate that the present PLA can be used for packaging of Danbo cheese for a shelf life maximum of 56 days in order to protect against both moisture loss and lipid oxidation.     

Active coating and modified-atmosphere packaging to extend the shelf life of Fior di Latte cheese

In this work the combination of active coating and modified-atmosphere packaging (MAP) was used to prolong the shelf life of Fior di Latte cheese. The active coating was based on sodium alginate (8% wt/vol) containing lysozyme (0.25 mg/mL) and EDTA, disodium salt (Na₂-EDTA, 50 mM). The MAP was made up of 30% CO₂, 5% O₂, and 65% N₂. The speed of quality loss for the Fior di Latte cheese, stored at 10°C, was assessed by monitoring pH and weight loss, as well as microbiological and sensorial changes. Results showed that the combination of active coating and MAP improved Fior di Latte cheese preservation, increasing the shelf life to more than 3 d. In addition, the substitution of brine with coating could allow us to gain a double advantage: both preserving the product quality and reducing the cost of its distribution, due to the lower weight of the package.     

A comparative study on the effect of packaging material and storage environment on shelf life of fresh bell-pepper

The effect of packaging materials [low density polyethylene (LDPE), polypropylene (PP)] and storage environment [modified atmospheric packaging (MAP)] on shelf life enhancement of bell pepper in terms of quality attributes such as physiological weight loss, ascorbic acid, texture, surface colour and subjective quality analysis have been studied at ambient and refrigerated condition. Different packaging techniques used for the experiment were MAP with LDPE, MAP with PP, MAP in perforated LDPE films, MAP in perforated PP films, shrink packaging with bi-axially oriented PP (BOPP) film and vacuum packaging with PP film. The in-pack bell pepper created a suitable headspace environment with low O₂ and high CO₂ concentrations, which resulted in a better retention of freshness of the vegetables and its marketability. Shrink packaging with BOPP film could not yield better result under ambient storage because of high water vapor transmission rate of the film and consequently loss of turgidity of the vegetables. Among different packaging techniques and storage conditions, MAP with PP film in refrigerated condition was found to be the best followed by vacuum pack with PP film in refrigerated condition and could be used to store for 20 days for bell pepper with maintenance of texture, colour, ascorbic acid and marketability. It is also inferred that under ambient conditions, bell pepper could be stored for 4 days using ventilated LDPE and PP as MAP storage. Further studies are needed to evaluate the sensory aspects, as well as to microbiological evaluation to characterize the fresh bell pepper during storage.