Storage Of Cheese Research Articles

The Current Prevalence of the Food-Borne Shigella Spp in Local Stored Cheese in Al-Diwaniyah City, Iraq: The Virulence ipaH and uidA Genes as Targets for a Molecular Study

The current study was carried out to evaluate the current prevalence of the food-borne pathogen; Shigella spp., in local stored cheese in Al-Diwaniyah City, Iraq, by using the virulence ipaH and uidA genes as targets for molecular tools. The study included the bacterial cultivation of 450 local cheese samples (collected during June to September, 2022) utilizing conventional methodology. The recovered Shigella spp. isolates were subjected to a real-time PCR (RT-PCR) that focused on the genes mentioned above. The results of the cultivation revealed the presence of 110 (24.4%) Shigella spp. isolates in the examined cheese samples. The RT-PCR showed that the virulence genes were identified in 84 (76.4%) and 98 (89.1%), respectively, in the bacterial isolates, which indicated the existence of Shigella dysenteriae. The current findings indicate the presence of Shigella spp. in local cheese, which needs urgent control to eliminate the source of infection or contamination.

Effect of packaging technology on ripening events occurring during storage of portioned PDO Italian semi-hard cheese

The aim of the present study was to assess the ability of the packaging technology (vacuum, VAC, and modified atmosphere, MAP) to preserve the microbiological, physicochemical, and sensorial properties of already ripened and portioned PDO Italian semi-hard cheese during 120 days of storage at 8 °C. Results were compared with those obtained by analyzing the original not-packed cylindrical wheel stored at 8 °C (NP). Samples packed under MAP showed yeasts’ proliferation with a final count of 4.68 Log cfu g−1, similar to that detected in the NP cheese wheels at 120 days of storage. In VAC samples yeasts did not proliferate, maintaining constant levels during time. Differently from the original wheels which showed a hardness increase in concomitant with a moisture loss during storage, packed samples under both VAC and MAP did not lose water preserving the original hardness of the product. At the same time, the packaging technology did not influence the proteolysis index in comparison to NP cheese. However, in MAP samples already at 30 days of storage different volatile compounds were produced in comparison with NP and VAC cheeses, suggesting that the modified atmosphere into the MAP pack promoted alternative microbial metabolisms and final products characterized by different volatile profiles. The study clearly demonstrated that the choice of packaging technology has an impact on the development of peculiar attributes of PDO cheeses, that are required by specific regulations in order to preserve their typicality and satisfy the consumers.

Utilisation of Potassium Chloride in the Production of White Brined Cheese: Artificial Neural Network Modeling and Kinetic Models for Predicting Brine and Cheese Properties during Storage

Excessive sodium consumption is a worldwide problem, prompting the industry to develop sodium-reduced products and substitute salts. High sodium consumption is a significant risk factor for high blood pressure, cardiovascular disease and kidney disease. Excessive sodium intake also impairs the immune system in the gastrointestinal tract. Potassium chloride (KCl) is the most commonly used mineral salt due to its similarity to sodium chloride (NaCl), and its consumption has been shown to lower blood pressure when consumed in adequate amounts. The aim of this study was to partially replace NaCl with KCl at levels of 25%, 50% and 75% in the brine used to make white brined cheese. Parameters such as acidity, total dissolved solids, salinity, conductivity, colour, texture and sensory properties were evaluated during a 28-day refrigerated storage period. KCl can replace NaCl by 50%, and no significant differences in physicochemical and sensory parameters were observed during cheese storage compared to the control sample. In addition, the study investigates the use of Artificial Neural Network (ANN) models to predict certain brine and cheese properties. The study successfully developed four different ANN models to accurately predict various properties such as brine pH, cheese colour and hardness over a 28-day storage period.

Reduction of Total Phenols in Virgin Olive Oil as a Preservation Medium during Cold Storage of Whey Cheese and Tofu.

Virgin olive oil, known as a good source of health-promoting hydrophilic phenols, is traditionally used as a medium for preserving various foods. Phenols in general can form complexes with proteins, but there is little information on the direct contact of virgin olive oil with protein-rich food during long-term storage. In this study, the dynamics of the decline of total phenols in oil used as preservation medium for a traditional (whey cheese skuta) and a modern product (tofu) were compared. Pieces of skuta or tofu immersed in virgin olive oil at different food-to-oil mass ratios were stored in the refrigerator for up to 21 days. The oil quality indices, water content and the total count of aerobic mesophilic bacteria in the immersed materials were monitored. To determine the total phenols in the oil, the optimal conditions of the Fast Blue BB test, which is a suitable alternative to the standard method, were tested and selected. The effect of both materials on the indicators of hydrolytic and oxidative deterioration of the oil is almost identical (a gradual decrease), which is most likely due to the continuous release of water from the immersed food. A sharp decrease in total phenols in the oil (by about 50 %) after seven days of storage in contact with both materials indicates a combination of causes (water-to-oil migration and phenol-protein interactions). The form of the rational function is highly representative of the decrease in total phenols during the first seven days of tofu/oil storage, indicating a very rapid interaction with tofu proteins. The preservative effect of virgin olive oil in terms of microbiological spoilage was not observed. The results of this study contribute to the knowledge on the dynamics of phenol-protein interactions and emphasise the need for further investigations on traditional or newly used protein-rich foods preserved in direct contact with virgin olive oil, taking into account possible changes in the functional, nutritional and sensory properties of phenols and proteins.

Preparation and characterization of carboxymethylated pullulan/butyric acid-modified chitosan active sustainable bi-layer coatings intended for packaging of cheese slices

Dependence of the food industry on conventional plastic and the generation of enormous amounts of food waste caused by microbiological spoilage have been imposed as inspiration for this work, to develop active sustainable packaging for sliced cheese using the bi-layer design. Pullulan was modified using a green approach to obtain a polyanionic character in the coating formulation. Chitosan, which has a cationic character in an acidic environment, has been modified using a butyric acid to obtain an amphiphilic character. The formed active bi-layer has demonstrated an improved barrier (decreased permeability for moisture vapor 72.2 and 77.7 times) and mechanical properties (increased tensile strength value up to 3.9 and 9.4 times) compared to the monolayer films. A novel approach to microbiological control of sliced cheese has been established, which implies a synergistic effect of Helichrysum italicum essential oil (EO) and corresponding hydrolate (HY) incorporated in separated layers. This design has ensured avoiding surfactants and preserving cheese's sensory properties, prolonging its shelf-life by 50 % at least. Improvements in cheese storage conditions using this packaging lie in the improved barrier, mechanical and antimicrobial properties, the order of lamination, and a good covering of the cheese surface by spraying.

Psychrotrophic Bacteria and Yeast Populations in Turkish White and Tulum Cheeses

In this study, pH and microbiological (psychrotrophic bacteria and yeast) properties of White and Tulum cheeses were investigated. According to the results of our study, the lowest pH value identified was 4.42, and the highest pH was 5.84 in the cheese samples. Psychrotrophic bacteria counts ranged from 4.15 to 6.21 log CFU/g for White cheese and 4.02 to 6.15 log CFU/g for Tulum cheese. Psychrotrophic yeast counts ranged from 2.98 to 7.58 log CFU/g for White cheese and 2.99 to 6.77 log CFU/g for Tulum cheese. The highest values of psychrotrophic yeast were detected in the Tulum cheese samples. As a result, it was determined that the numbers of psychrotrophic bacteria and yeast were high in both Tulum and White cheese samples. These high numbers of psychrotrophic microorganisms during cheese storage in the refrigerator may increase even further and reduce shelf life. To extend the shelf life of these cheeses, it is recommended to ensure hygienic handling practices and explore the use of natural preservatives or modified atmosphere packaging.

Frozen cheese curd as an intermediate for cheese making – homogenization as a tool to regain techno-functional properties

This study investigated the effect of milk homogenization/fat globule size on the plasticization of fresh and frozen stored cheese curd and its respective oiling-off behavior. The cheese was frozen either slowly in a freezing chamber or quickly with liquid nitrogen to study the influence of freezing, frozen storage, and thawing. For non-frozen cheese curd, a one-stage homogenization at 2 MPa before renneting still leads to plasticization, while relative oiling off is reduced from 2.6 to 1.9%. This was explained by reduced fat globule size and an increased surface area covered by whey proteins and casein, which is denser and more stable than the native fat globule membrane. For homogenization pressures above 4 MPa, no plasticization was observed. However, freezing and thawing counteract mild homogenization, so minor oiling off occurs, and flowability is enhanced. Extending frozen storage time up to 3 months did not result in more oiling off or higher tan δ values. Moreover, there was no significant effect between the two freezing methods. In conclusion, freezing and frozen storage for up to 3 months is a valid method to preserve cheese curd as techno-functional properties are regained after thawing.

Effect of Essential Oils and Dried Herbs on the Shelf Life of Fresh Goat Lump Cheese.

In recent years, the use of natural preservatives in food products has gained significant attention due to their potential health benefits and effectiveness. A standardized microbiological analysis was conducted on Slovak farm-produced lump goat cheese samples to determine the antibacterial activity of dry herbs and essential oils added to vacuum-packed goat cheese. We employed five dried herbs and five essential oils derived from the same plants. The microbiological quality of 145 fresh and vacuum-packed goat cheese samples was assessed. The number of coliform bacteria, total viable count, lactic acid bacteria, and microscopic filamentous fungi were examined in raw cheese samples stored for 12 days at 4 °C. All cheese samples were vacuum-packed (control samples were packed without vacuum). This study evaluated the potential benefits of using essential oils and dried herbs from thyme (Thymus serpyllum L.), black pepper (Piper nigrum L.), clove (Eugenia caryophyllus Thunb.), mint (Mentha × piperita L.), and basil (Ocimum basilicum L.) as preservatives. The essential oils were obtained from Hanus Ltd., Nitra, Slovakia, and were applied at a concentration of 2%. The dried herbs were obtained from Popradský čaj (Poprad, Slovakia) and Mäspoma Ltd. (Zvolen, Slovakia). The results showed that all microorganism groups were significantly reduced in cheese samples following the application of essential oils throughout the entire storage period. During the preservation of cheese samples in polyethylene bags used for vacuum packing food, Lactococcus garvieae, L. lactis, Enterobacter cloacae, and Serratia liquefaciens were the most frequently isolated microbiota. Essential oils and dried herbs demonstrated antimicrobial potential during the storage of vacuum-packed goat cheese.

A strategy to prolong cheese shelf-life: Laminated films of bacterial cellulose and chitosan loaded with grape bagasse antioxidant extract for effective lipid oxidation delay

This study presents an innovative approach to developing bioactive composite films for food packaging applications. Laminated films composed of bacterial cellulose (BC) and chitosan were enriched with grape bagasse extract (GE) and glycerol. GE provides antioxidant capacity. Glycerol was added as plasticizer. The formulations were systematically varied to assess their mechanical and thermal properties. The assembly of the films demonstrated robust interaction between components, resulting in enhanced mechanical strength. Tensile tests revealed that GE and glycerol concentrations significantly influenced the tensile strength and elongation properties Films were obtained with Tensile Strength values that ranged between 16.92 and 32.71 MPa, but with an increase of up to 4 times in the percentage of elongation (from 2.33 to 8.63%) compared to films without GE. Puncture tests indicated that the incorporation of GE and glycerol played pivotal roles in improving puncture resistance. Predictive models were developed for better understanding. The laminated films were applied as separators for Havarti cheese, demonstrating their ability to mitigate lipid oxidation and maintaining antioxidant properties during storage. After 60 days of cheese storage, 67.3% decrease in the lipid oxidation was obtained. The findings suggest that laminated BC-chitosan films enriched with GE and glycerol could serve as effective, eco-friendly packaging materials with enhanced mechanical strength and antioxidant functionality for extending the shelf life of food products.

Contribution of salting on the safety assurance of artisanal “Bagaces” cheese, a Mesoamerican firm dry-salted unripe cheese

The efficacy of salting to ensure the safety of “Bagaces” cheese was assessed. Six producers with different processing practices were visited to develop a standard processing protocol for “Bagaces” cheese making. The effect of two different salting methods (brine or dry direct salting) and two cheese geometries (block or cubes) were assessed on product pH, water activity (Aw) and salt content. Both cheese geometry and salting method significantly influence the salting kinetics (p = 0.0027 and p = 0.0187, respectively), yet based on the physicochemical properties measured and its influence on pathogens growth based on previous studies, salting may not guarantee the safety of the final product as a critical measure of control since the growth of reference pathogens is likely to occur. Therefore, milk pasteurization, refrigeration during cheese storage and distribution, and strict application of good manufacturing practices are required for the safety assurance of this artisanal Mesoamerican cheese.

Determination of phthalate esters contents in different types of cheese produced and consumed in Saudi Arabia

Background: Phthalates’ esters are commonly incorporated into plastic materials to enhance their elasticity, thereby facilitating their migration into food items. Aims: To evaluate the levels of phthalate esters in six distinct varieties of locally produced cheese and sold in Saudi Arabia, at the time of purchase (t=0) and after storage for one and two months. Methods: Six types of local cheeses (Cheddar, Mozzarella, Feta, Cheeseburger slices, Haloumi and Kashkaval) were purchased and analyzed at three different intervals: at the time of purchase (t=0), after one month, and after two months of storage. The Phthalate ester concentrations were determined using indirect gas chromatography with results expressed in mg/kg of cheese. Results: Among the cheese samples analyzed, di(2-ethylhexyl) phthalate (DEHP) was found to be the most prevalent. Halloumi cheese exhibited the highest average concentration of DEHP (4.29 ± 0.51 mg/kg) followed by Mozzarella cheese (3.65 ± 0.46 mg/kg). After two months of storage, more than two-thirds (n=13) of the samples exceeded the permissible limits content of DEHP content while one-third (n=6) and more than half (n=9) exceeded the limits for dibutyl phthalate (DBP) and di-n-octyl phthalate (DNOP), respectively. The levels of phthalates in all cheese types increased with prolonged storage duration with Cheddar cheese exhibiting the highest rate of increase, exceeding fivefold (from 0.34 to 2.29 mg/kg). Conclusion: This study confirms the presence of phthalate in cheese samples, with concentrations varying depending on the cheese type, specific phthalate compound, and storage duration. Heightened consumer awareness regarding cheese storage practices is imperative to mitigate potential health risks associated with phthalate consumption. Keywords: Phthalate, cheese, chemical analysis, content, Saudi Arabia.

Distribution of mycotoxins during manufacture and storage of cheeses – A review

The distribution of mycotoxins during cheese production and storage is a complex process that depends on several factors, including milk quality, cheese type, storage conditions, and the presence of competing microorganisms. This paper investigates the occurrence and distribution of mycotoxins in curd/cheese/whey during different cheese processes and the effect of ripening/storage time on mycotoxin levels in the final product using a review approach. The paper covers the major mycotoxins that can contaminate cheese, including aflatoxins, ochratoxin‐A, roquefortine‐C, mycophenolic acid, and beauvericin. Overall, it synthesises the existing understanding of the spread of mycotoxins during cheese production and storage.

Effect of storage temperature on the change of microbiological indicators of fresh soft cheese

In Ukraine, there is a tendency to increase the production of soft, fresh cheeses due to their technological features. The advantages of producing this product include efficient use of raw materials; the ability to sell the product without ripening or with a short ripening period (no more than 14 days); and high quality indicators. In general, cheese is considered a complete food product that covers part of a person's daily needs for nutrients and biologically active substances. Due to martial law in the country, loyalty in the sale of products plays a unique role, but the temperature regime of storage affects the safety of cheese. Therefore, the study aimed to determine the sanitary quality of soft, fresh cheese and to justify the parameters of product storage at a temperature of 6 °C. The research was conducted at the Regional State Laboratory of the State Service of Ukraine for Food Safety and Consumer Protection in Poltava Oblast and at the Department of Livestock Products Processing Technology laboratory of Poltava State Agrarian University. The research objects were samples of soft, fresh cheese without fillers produced at the Milk Local Product Expert Center of the Faculty of Animal Production and Food Technology. The indicators stipulated by the regulatory document for soft cheeses 4395:2005 “Soft cheeses. General technical conditions”. It was established that the investigated cheese (sample No. 6) met the requirements of the current standard in terms of organoleptic (appearance, taste and smell, consistency, dough color, pattern, shape), physicochemical (mass fraction of fat, table salt, water) and physicochemical parameters. Specific physicochemical characteristics (mass fraction of moisture, table salt, and fat in dry matter) of the cheese, according to the tests, were within the limits specified by SSTC. The studied samples of fresh soft cheese regarding microbiological parameters (pathogenic microorganisms, particularly Salmonella, Listeria monocytogenes, and Staphylococcus aureus) complied with regulatory documents when they were stored at +6 °C for two days. At the same time, it has been proven that storage of fresh soft cheese without fillers at a temperature of +20 ± 0.5 °C leads to the growth and presence of coliform bacteria in the E. coli group. As early as 48 hours later, the products did not meet the regulated norms of the current national standards.

Safe and sustainable food packaging: Argemone albiflora mediated green synthesized silver-carrageenan nanocomposite films

Silver-Carrageenan (Ag/Carr) nanocomposite film for food packing application by the green method using Argemone albiflora leaf extract has been developed in this study. Different plant parts of Argemone albiflora (blue stem prickly poppy) are used all over the world for the treatment of microbial infections, jaundice, skin diseases etc. GC–MS analysis was used to examine the phytochemical found in the Argemone albiflora leaf extract which reduces the metal ions to nanoscale. The biopolymer employed in the synthesis of nanocomposite film was carrageenan, a natural carbohydrate (polysaccharide) extracted from edible red seaweeds. We developed a food packing that is biodegradable, eco-friendly, economical and free from harmful chemicals. These films possess better UV barrier and mechanical and antimicrobial properties with 1 mM AgNO3 solution. The presence of silver nanoparticles in the carrageenan matrix was evident from FESEM. The mechanical properties were analysed by a Universal testing machine (UTM) and different properties like water vapour permeability (WVP), moisture content (MC) and total soluble matter (TSM) important for food packing applications were also analysed. The antimicrobial properties of the synthesized film samples were studied against E. coli and S. aureus pathogenic bacteria. These films were employed for the storage of cottage cheese (dairy product) and strawberries (fruit). This packing increased the shelf life of the packed food effectively. Ag/Carr films are biodegradable within four weeks.

Development and characterization of cellulose nanofiber reinforced hydroxypropyl methylcellulose films functionalized with propolis-loaded zein nanoparticles and its application for cheddar cheese storage

Cellulose nanofiber (CNF) reinforced hydroxypropyl methylcellulose (HPMC) films were functionalized with propolis-loaded zein nanoparticles (ZNP) to develop active, printable, and heat-sealable films. The films with 0, 0.10, 0.25, 0.50, or 0.75 mg/mL propolis-loaded ZNP, named 0ZNP, 0.10ZNP, 0.25ZNP, 0.50ZNP, and 0.75ZNP, respectively, were characterized for their mechanical, physicochemical, structural, functional and optical properties and antioxidant activity. The addition of propolis-loaded ZNP did not change tensile strength (P > 0.05), but increased elongation at break (from 24.72 to 36.58 %) (P < 0.05) for 0.25ZNP film. A water contact angle increased significantly (P < 0.05) for 0.50ZNP (~45 %) and 0.75ZNP (~137 %) films. The 0.25ZNP and 0.75ZNP films were evaluated for packaging cheddar cheese under refrigerated storage for 30 days, and resulted in comparable water activity, pH, titratable acidity, and lipid oxidation (P > 0.05) with those packaged by LDPE film and vacuum package. The developed films can function as eco-friendly alternatives to single-use plastic food packaging.

Beyaz Peynirden İzole Edilen Laktik Asit Bakterilerinde Karotenoid Gen Varlığı

Carotenoids are organic pigments with antioxidant properties that are commonly found in nature. Various types of carotenoids are produced by microorganisms. In this study, we aimed to determine the microorganisms with potential carotenoid production and yellow-orange pigment production during the storage of white cheese below 10°C. Five different white cheeses with pigmentation problems were obtained from the provinces of Istanbul and Kocaeli. Colonies with a typical yellow-orange color and morphological differences were selected on MRS and M17 media. The presence of carotenoid genes in 136 selected colonies was determined by agarose gel electrophoresis using colony PCR, and carotenoid genes were detected in 6 colonies. According to the 16S rRNA sequence results, one of the 6 bacterial colonies carrying the carotenoid gene was Lactococcus lactis, another was Enterococcus faecium, and the rest was Lactobacillus plantarum. In addition to genotypic identification, Gram-staining was performed to determine the phenotypic characteristics of bacteria carrying the carotenoid gene, and it was found that six bacteria had Gram-positive and bacilli morphology. These results showed that some carotenoid producer strains existed in the microbioata of cheeses during cold storage.

Impact of Socioeconomic and Demographic Factors on the Physicochemical and Microbiological Quality of Artisanal Cheeses from Northern Peru

Goat cheese offers significant nutritional benefits due to its enhanced digestibility and assimilation. In Peru, the province of Sullana stands out as the largest producer of this cheese. However, there is limited knowledge regarding the socioeconomic factors of its producers, as well as the physicochemical and microbiological characteristics of the cheese. The study was developed in 3 aspects, socio-economic based on a descriptive exploratory methodology, with a mixed approach, 14 presidents of producer associations participated. Fourteen samples of fresh artisanal cheese from goat producers' associations from Marcavelica, Lancones and Salitral were stored at 4°C under aseptic conditions for physico-chemical characterisation and microbiological analysis. In relation to socioeconomic factors, the findings of the survey indicate that 42.9% were aged 56 years or older and possess only primary education. Additionally, 57.1% received Good Manufacturing Practices (GMP) training, 86% reported a lack of water and drainage services, 21% reported having access to conventional electricity and 79% reported using solar panels. These make an improvement in the training of cheese producers imperative. Regarding the physicochemical properties (pH, acidity, humidity and ash content), the cheeses were within the parameters allowed in DS N° 007-2021-MINAGRI. However, it was observed that 29% and 50% of the samples exhibited a high count for aerophilic mesophiles at 24 (≥ 2.51 x 106 CFU/g) and 48 (≥ 2.34 x 106 CFU/g) hours, respectively (COVENIN 3338:1997). 79% of the samples tested positive for both total and fecal coliforms (DS N° 007-2021-MINAGRI) in which 43% exhibited a high count for E. coli (&gt;3.6 MPN/g). Conversely, the presence of S. aureus (&lt;10) was within the optimal parameters while Salmonella spp. and L. monocytogenes were not detected. The lack of adequate infrastructure for the milking process, the production, storage and transportation of cheese, is presented as the most significant aspect. These findings may pose a risk to consumers’ health, highlighting the necessity to establish projects that strengthen these aspects in order to enhance cheese production.

Effectiveness of Zinc Oxide Nanoparticles and Artemisia herba alba Extract on the Chemical Composition of Soft Cheese

This study was conducted to assess the impact of ZnONPs and Artemisia herba alba extract loaded on manufacture edible gelatin in the chemical composition of cheese during the various storage periods and five transactions of cheese were manufactured which included the (T1) control sample, (T2) membrane of gelatin without adding, membrane of gelatin with loaded of ZnONPs (T3), membrane of gelatin with loaded Artemisia herba alba extract (T4) and (T5) was added ZnONPs and Artemisia herba alba extract on edible gelatin. The results of the cheese storage showed that the humidity rate had decreased morally ( p < 0.05) up to the end of the storage period and the transaction (T1) was more moisture loss to record (53.34), also found that protein, fat and ash ratios did not show moral differences at the time of one day compared with the control sample (T1) These ratios then gradually increased as long as conservation lasted and reached its highest values at 21 days. pH values have decreased morally to be at the end of the storage period between (6.10-6.26) compared with the control sample which was (5.78) and found that the fatty acid values of all transactions were morally low compared to the control sample (T1) At the time of one day, the ratio of free fatty acids rose and reached its highest values among (0.57-0.40)% for all treatments compared to the (T1) control treatment at the end of the storage period which reached (0.65%).

Polylactic Acid-Based Film Modified with Nano-Ag-Graphene-TiO2: New Film versus Recycled Film

The increase in the polymer-based materials needs has induced along the waste accumulation, thus argued higher interest in recycling. The study aims to assess the structural, morphological, mechanical resistance, physical–chemical and biochemical characteristics, as well as the preservative role during the curd cheese storage of a recycled polylactic acid (PLA)-based film modified with Ag-graphene-TiO2 nanostructured composite, obtained by recovering the composite from the used film, followed by its incorporation in new PLA. The breaking load of the recycled film was 24% lower than that of the new film and 10% higher than of the neat PLA. Differential scanning calorimetry (DSC) showed changes of the recycled PLA’s surface tension and crystallization degree in a greater extent than in the newly prepared film, revealing better incorporation of the recovered composite into the PLA matrix. Fourier transformed infrared spectroscopy showed the formation of C–O–Ti bridges between composite and PLA both in new and recycled film. Oxygen transmission rate (OTR) of the new and recycled film decreased by 33% and 45%, respectively, in comparison with reference PLA. The curd cheese was successfully stored in the recycled packaging; the organoleptic characteristics of cheese wrapped in recycled film were superior in comparison with the new film. The variation of fat and protein contents and mass loss was the lowest when the recycled film was used as packaging material. The study successfully showed the possibility to recover and recycle the used PLA-based films modified with inorganic nanocomposites.

The Effectiveness of a Bilayer from Gelatin and Carboxymethyl Cellulose Supported with Zinc Oxide Nanoparticles on Microbial Load of Soft Cheese Storage at Refrigerator Temperature

The study was conducted in the laboratories of the Department of Food Sciences - College of Agriculture at the University of Tikrit for the period from the beginning of November 2021 to the end of October 2022 with the aim of testing the efficiency of wrapping soft cheese samples with gelatin film compounded with carboxy methyl cellulose derivatives (CMC) or combined with nanoparticles of zinc oxide. (ZnO-NPs) by determining the microbial counts after storage of samples for 35 days in the refrigerator temperature (4 ºC ± 2). The results showed that cheese samples were contaminated with total microbial counts at 35 days of storage for each T2 and T3 at 1.30, 0.70, CFU/g, respectively, compared with their bacterial count in the control group at 14 days storage, which was at 2.60 CFU/g. The coliform bacteria also appeared in T2 and T3 at Log 0.7 and 0.3 CFU / g, respectively, compared with their counts in T1, at 2.51 CFU / g, while the fungi values of treatment T3, T2 were log 2.3 and 0.0 CFU/ g, respectively, compared to their counts in T1, which accounts to log 2.20 CFU /g at 14 days storage.