File Name: food packaging and shelf life .zip
Fresh products are characterized by reduced shelf-life because they are an excellent growth medium for a lot of microorganisms. Therefore, the microbial spoilage causing significant food supply losses has become an enormous economic and ethical problem worldwide.
The antimicrobial packaging is offering a viable solution to tackle this economic and safety issue by extending the shelf-life and improving the quality and safety of fresh products. The goal of this study was to investigate the effects of a food contact surface of polyethylene terephthalate PET functionalized with the previously characterized antimicrobial peptide mitochondrial-targeted peptide 1 MTP1 , in reducing the microbial population related to spoilage and in providing the shelf-life stability of different types of fresh foods such as ricotta cheese and buffalo meat.
Modified polymers were characterized concerning the procedure of plasma-activation by water contact angle measurements and Fourier transform infrared spectroscopy measurements in attenuated total reflection mode ATR-FTIR.
Results showed that the MTP1-PETs provided a strong antimicrobial effect for spoilage microorganisms with no cytotoxicity on a human colon cancer cell line. Finally, the activated polymers revealed high storage stability and good reusability. This study provided valuable information to develop alternative antimicrobial packaging for enhancing and extending the microbial quality and safety of perishable foods during storage.
Short shelf-life of fresh foods represents one of the main limitations for the commercialization of this class of products, mainly due to their high content in nutrients and superficial moisture which leads to the fast growth of spoilage and pathogenic microorganisms Aymerich et al. Indeed, it is well-known that microbial growth on the surface of a product is often responsible for the undesirable changes in flavor, aroma, and other organoleptic characteristics of fresh foods, which lower their quality and shorten their commercial life Mead, ; Samelis, ; Petrou et al.
Although the exact figure of the total economic loss due to food spoilage is hardly to estimate, it is clear that it constitutes an enormous financial burden Blackburn, accounting for 1. As a preservation technique, the refrigeration is necessary to maintain the microbial quality of fresh products, but it does not guarantee by itself a long shelf-life, which in the case of some foods amounts to a time period of about 4—5 days.
Therefore, demand for safe fresh products presents major challenges to the food industry to develop innovative strategies for improving the preservation process and prolonging the storage time maintaining both the natural appearance and safety of foods by reducing or eliminating spoilage bacteria.
Active packaging is the most relevant innovative idea applied for consumer satisfaction. Among the active packaging technologies, antimicrobial packaging is considered one of the most promising.
These systems are based on the immobilization of antimicrobial agents on the surface of polymers, whose usage has strongly increased due to their large variety and the different compositions available, which make possible to adopt the most convenient packaging solutions, focusing on the specific needs of each product.
One of the most common support that has found increasing applications within the packaging field is the polyethylene terephthalate PET , a simple long-chain polymer, whose chemical inertness and physical properties have made it particularly suitable for different food applications. Some antimicrobial packages use immobilized antimicrobial peptides AMP to suppress the growth of microbes Malhotra et al.
Nevertheless, three main characteristics that are shared by almost all known AMPs, can be distinguished: small size, highly cationic character, and tendency to adopt amphipathic structures Nakatsuji and Gallo, These physicochemical properties make AMPs able to interact with the negatively charged microbial membranes. However, to serve as effective coating agents, the AMPs must meet several prerequisites, which include the retention of broad-spectrum antimicrobial activity once bound to packaging materials.
As many naturally occurring peptides lack the ability to retain these properties, there is a need to develop new and more effective AMPs, with the aim to increase safety and shelf-life of food products.
Finally, the compound exhibited significant bactericidal activity against Listeria monocytogenes , one of the most important foodborne pathogens. The aim of the present study was to develop a new class of packaging materials, functionalized with the bactericidal peptide MTP1 and to evaluate both the usefulness and effectiveness of the aforementioned active coatings on the microbial quality and safety of fresh perishable products and the potential extension of their shelf-life.
For plasma treatment and further peptide immobilization, the PET films were cut into disk-shaped pieces. The following parameters were modified to identify the best operative conditions: exposure time T 10—20—30—50—— s ; molecular oxygen concentration O 2 10—50— sccm ; partial gas pressure P 0. Spectra have been automatically corrected from the background using Ominc software Thermo Scientific, United States.
After incubation, the liquid solution of unbound peptide was removed manually and the functionalized PETs were extensively rinsed in water and DMSO in order to remove the traces of non-covalently bound peptide before performing all the surface characterizations. Once immobilization was completed, the supernatant solutions were recovered after 24 h incubation and chromatographically analyzed to indirectly estimate the amount of the peptide attached to the polymeric surfaces.
A reference solution was prepared with the initial peptide concentration used for the functionalization procedure under the same reaction conditions and run in parallel. Therefore, by knowing the added peptide reference solution , the amount of peptide not bound to the polymers expressed as a percentage was determined by comparing the peak area.
A calibration curve of the C18 column using different MTP1 concentrations was built. All measurements were performed in triplicate on three different preparations. A total of three random samples of buffalo ricotta cheese g were collected from a dairy factory. Non-functionalized PETs were used as control. Microbiological analyses were performed at t 0 beginning , t 1 4 days , and t 2 10 days in contact with the MTP1-PETs.
Further fold dilutions of the homogenates were made. Water Buffalo n. At 90 days of the aging period, three sirloin steaks SS were chosen. Analytical determinations were performed at t 0 beginning and t 1 4 days after contact with the peptide.
On buffalo meat samples was performed: a Texture profile analysis TPA , a compression test for determining the textural properties of meat pieces Ruiz de Huidobro et al. For all rheological analyses, the steak cores were collected in parallel to the muscle fibers, using a hand-held steel cork borer. A cylindrical 10 mm-diameter probe of ebonite was used for the TPA tests.
The sensory attributes of buffalo meat and ricotta buffalo cheese were estimated by a panel of five panelists Altieri et al. The samples treated with not-functionalized PETs were used as control. Panelists scored each sample with a point scale, ranging from 0 attributes most disliked to 5 attributed most liked. Two pieces of each sample, buffalo meat and ricotta cheese, were served to panelists at each sample time.
HT cells kindly donated by Dr. Experiments were performed in quadruplicate. Cells with the addition of not-functionalized PETs were set as negative control. All experiments were performed at least five times. Data were analyzed using GraphPad Prism 5. Packaging has a fundamental role in ensuring the safe delivery of goods throughout supply chains to the end consumer Lindh et al.
In this context, polymeric materials cover a large section of requirements in the field of the food industry and provide support surfaces for the immobilization of biologically active molecules. Specifically, PET is actually one of the most common polymers used in the food packaging, because of its physicochemical and mechanical properties and it is also relatively inexpensive to produce Siracusa, However, surface properties of PET are usually inadequate in terms of wettability and adhesion properties, so it should be modified in order to improve its desired surface features and enhance its suitability, prior to any further processing, such as functionalization with biologically active molecules.
Because of this procedure, the PET wettability is enhanced, and a more hydrophilic surface is created, rendering the polymer suitable for the preparation of new materials. Control samples not subjected to radiofrequency cold plasma treatment and incubated in aqueous peptide solution displayed an FTIR spectrum almost identical to that of Figures 2A,B data not shown Edge et al.
Figure 1. The measurements were performed on five samples in duplicate. Figure 2. In order to consider PET materials as promising candidates for applications in the food industry as antimicrobial packaging that are able to efficiently increase the food quality and safety, the AMPs used as coating agents must retain several prerequisites, including the broad activity spectrum and the biocompatibility.
Therefore, it is firstly important to develop an effective surface tethering strategy that would impart the desired antimicrobial characteristics of the targeted biomaterial. This challenge strongly depends on the appropriate peptide concentration required to ensure a high efficiency of the immobilization procedure used and a great surface coating. The coupling yield was further confirmed by interpolation using a six-point calibration curve, which was generated utilizing known MTP1 concentrations measured using an analytical balance Supplementary Figure 1 insert.
An important pre-requisite for AMP-coated packaging is the stability of the immobilized peptides. Therefore, the functionalized PET disks were incubated under different physiological conditions i. In addition, no peptide-release was detectable even after prolonged incubation times until to 72 h in all the conditions analyzed data not shown , thus highlighting the high stability of our system, that makes it an appropriate candidate for food applications.
Fresh food such as dairy products and meat because of their specific composition represent good support for a rapid growth of spoilage microorganisms that strongly influence the storage life of this class of products. In the case of cheese and meat, parameters such as water activity, pH, temperature, types, and viability of contaminating microorganisms are reported as some of the key factors that affect their rate of spoilage.
Therefore, it is not surprising that these foods differ widely in spoilage characteristics. Among the troublesome microorganisms, yeasts and aerobic psychrotrophic Gram-negative bacteria can be considered the main causative agents of microbial spoilage and therefore they are recognized indicators of the hygienic quality of the foods.
Indeed, psychrotrophic bacteria can produce large amounts of extracellular hydrolytic enzymes, and the recontamination of food products with these bacteria is determinant for their shelf-life, while yeasts are responsible of the main food degradations. These microorganisms are able to grow under a great variety of conditions and to survive in different environments resulting in unwanted physical and chemical changes, altering texture, smell, taste, or appearance of fresh products and rendering them not feasible for human consumption anymore.
Therefore, extending the shelf-life of meats and dairy products represents the main challenge for food companies, and it is vital because, in the real world, these products do have fixed lifetimes after which they will perish.
With the aim to determine the possible influence of MTP1-PETs on the microbial growth in the products under investigation, the evolution of APC and yeast counts of samples treated with not-functionalized PETs control was assessed Figure 3. These results indicated that MTP1-PET films might be an effective coating to extend the fresh meat shelf-life, which is generally estimated to be 2—3 days beyond a sell-by date.
Figure 3. Not-functionalized PETs were used as control K. Besides, no significant differences in APC values were detected between samples of ricotta cheese stored on the PETs activated or not at day 10 of treatment, probably indicating the limited effect of long storage time on ricotta cheese preservation of the functionalized polymers Figure 3A. Similar results were obtained by evaluating yeasts growth Figure 3B.
Interestingly, the results obtained for ricotta cheese samples are very notable considering that the yeasts constitute the most representative microbiological typology that strongly affects the shelf-life of this class of products, although no limits were fixed by European rules. As shown in Figure 3B , PET-coated ricotta samples did exceeded this limit until the end of storage 10 days while the control samples reached the limit already after 4th day.
Representative APC and yeast plates were reported in Figure 4. Figure 4. During storage, food products undergo physicochemical, rheological, and sensory changes that may affect their organoleptic qualities and in turn, discourage their consumption.
In this context, it is essential for a packaging to preserve also the inherent qualities of a product during storage beyond the microbiological safety. Therefore, a detailed analysis concerning the aforementioned parameters was performed on the buffalo meat and ricotta cheese samples treated or not with MTP1-PETs at the investigation times.
All data are reported in Tables 1 , 2. Table 1. Table 2. As far as the physicochemical parameters is concerned, there were no substantial changes in the pH and a w values and in general no significant differences were found across all groups of meat and the dairy product following the MTP1-PET treatment during storage Tables 1 , 2.
Color of foods is another important parameter to evaluate their quality, since the consumers associate it with freshness. Finally, the rheological analysis evidenced no significant change in the textural qualities of the buffalo meat samples following the MTP1-PET treatments.
In addition to antibacterial activity, cytotoxicity is another important parameter influencing the application of any material for industrial and medical purposes. To this aim, cell viability was determined by exposing these cells to functionalized polymers for different time intervals, using the non-conjugated PET disks as control. As reported in Figure 5 , the mammalian cells remained viable up to 72 h of incubation with the functionalized PET, with no significant difference in cell viability in terms of absorbance between the controls and the MTP1-PET disks.
These results indicated that the amount of peptide immobilized on PETs was not toxic to mammalian cells, thus suggesting that the projected polymers could be considered safe to be applied as antimicrobial packages in the food industry. Figure 5.
To investigate the effects of packaging on the quality aspects of radish, Korean radish roots Raphanus sativus L. Lower color difference values were also found in this treatment. Both film packaged samples had lower scores of black spot, surface shrinkage, and fungal infection incidence which revealed significantly longer marketable periods. HDPE film packaged samples exhibited longer shelf life more than one and two months compared to control and unpacked samples, respectively. Results suggest that HDPE film packaging can extend postharvest life of radish while curing might have little but beneficial effects in maintaining the quality characteristics. To our knowledge, this is the first report on quality evaluation of Korean radish during an extended storage period simulating the Korean industrial practices.
Nano packaging is currently one of the most important topics in food packaging technologies. The aim of the application of this technology in food packaging is increasing shelf life of foods by preventing internal and external corruption and microbial contaminations. Use of silver nanoparticles in food packaging has recently attracted much attention. The aim of this study was to investigate the effect of nano-silver packaging in increasing the shelf life packages of nuts in an In vitro model. In this experimental study, the effects of different nano-silver concentrations 0, 1, 2 and 3 percent on biological and chemical properties of samples of nuts including walnuts, hazelnuts, almonds and pistachios were evaluated during 0, 3, 6, 9, 12, 15, 18, 21 and 24 months. Nano-silver also prevented growth of mold and so prevented aflatoxin production in all treatment groups.
Food packaging plays a vital role in preserving food throughout the distribution chain. Without packaging, the processing of food can become.
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USA info metergroup. Why do shelf-life testing? Insufficient packaging allows water activity in food products to rise or fall over time—causing undesirable physical changes, moisture migration, chemical degradation, and susceptibility to microbial growth. Over-packaging, on the other hand, is expensive and can erode profits. How can you figure out the exact amount of packaging your product needs?
Fresh products are characterized by reduced shelf-life because they are an excellent growth medium for a lot of microorganisms. Therefore, the microbial spoilage causing significant food supply losses has become an enormous economic and ethical problem worldwide. The antimicrobial packaging is offering a viable solution to tackle this economic and safety issue by extending the shelf-life and improving the quality and safety of fresh products. The goal of this study was to investigate the effects of a food contact surface of polyethylene terephthalate PET functionalized with the previously characterized antimicrobial peptide mitochondrial-targeted peptide 1 MTP1 , in reducing the microbial population related to spoilage and in providing the shelf-life stability of different types of fresh foods such as ricotta cheese and buffalo meat. Modified polymers were characterized concerning the procedure of plasma-activation by water contact angle measurements and Fourier transform infrared spectroscopy measurements in attenuated total reflection mode ATR-FTIR.
The shelf life of a food product refers to the length of time for which it can be stored, under specified conditions, while remaining in optimum condition and safe for consumption. The shelf life of a food begins from the time the food is produced and is dependent on many factors, such as the ingredients, processes, type of packaging and storage conditions. The shelf life will affect things such as stock storage times, delivery and distribution methods, and many retailers have very specific expectations in terms of the shelf life of listed products. All foods have their own distinctive characteristics that will affect their shelf life. These can be broadly divided into intrinsic characteristics, which are inherent to the composition of the food, such as its ingredients and formulation; and, extrinsic characteristics, which relate to the external environment but have an impact on the food, such as the storage temperature and packaging. Some characteristics prolong shelf life while others decrease it. Bacteria, yeast and mould growth can cause food spoilage or food poisoning.
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