نشریه فرآوری و نگهداری مواد غذایی
سال پانزدهم شماره 3 (پیاپی 39، پاییز 1402)

Nowadays, the demand for low-fat food products, such as cheese, has increased due to the increase in people's awareness about the relationship between fat and cardiovascular diseases. Therefore, the production of low-fat cheese with acceptable quality for consumers has great importance. The present study was conducted to investigate the effect of transglutaminase treatment and the addition of kappa-carrageenan gum, as a fat replacer, on the physicochemical, color and total acceptability of ultrafiltrated low-fat cheeses during 30 days cold storage (4 ◦C).

In this research, samples of ultrafiltrated low-fat cheese were produced from the retentate of ultrafiltrated milk. Milk protein concentrate powder (containing 80% protein and 0.6% fat) was used (as solution with 34% total solids) to reduce the fat content of the cheese samples and adjust the fat percentage to 8%. Kappa-carrageenan powder was used in 3 different levels (0, 0.03 and 0.06%) to produce gum-incorporated samples. After adjusting the amount of fat in the retentate and the addition of gum, the retentate was homogenized at 70 bar. After pasteurizing at 75°C for 15 seconds, the temperature of the samples was reduced to 32°C and transglutaminase was added at 2 levels (zero and 0.5 Unit/g protein). A low-fat sample, without enzyme and gum, was also produced as control sample.

Based on the results, all investigated variables had a significant effect on pH, soluble nitrogen and syneresis parameters (p<0.01); While these variables, except the amount of kappa-carrageenan, had no significant effect on the moisture content (p>0.05). The pH decreased by increasing the amount of kappa-carrageenan, while the amount of this factor increased in the presence of enzyme. Also, the pH showed a decreasing trend over the time. The amount of soluble nitrogen increased by increasing the amount of kappa-carrageenan in the low-fat samples; the addition of the enzyme caused a decrease in soluble nitrogen. On the other side, the amount of soluble nitrogen showed an increasing trend over the time. The syneresis of all low-fat samples decreased by increasing the amount of kappa-carrageenan and transglutaminase. The highest percentage of syneresis was related to the control sample and the lowest percentage was related to the sample containing 0.06% kappa-carrageenan and 0.5 units of transglutaminase. Moreover, increasing the amount of gum declined the color quality of the samples, but no significant difference (in terms of brightness) was observed between the control and the samples containing 0.03% kappa-carrageenan (p>0.05). According to the results of sensory evaluation, the sample containing transglutaminase enzyme (0.5 Unit/g protein) and 0.03% gum scored as the best sample in terms of total acceptance

The results of this research revealed that low-fat ultrafiltrated cheese with a desirable quality can be produced by application of proper concentrations of kappa-carrageenan and transglutaminase (0.03% and 0.5 Unit/g protein, respectively).

To minimize the use of antibiotics, additives, and chemical preservatives , it is possible to incorporate natural antimicrobial substances into packaging. Recent studies focusing on developing and evaluating edible films have highlighted the effectiveness of essential oils like clove, cinnamon, ginger, and basil in protecting against microbial growth, preventing food spoilage (both chemical and microbial), and reducing food waste. Films containing gelatin display impressive mechanical strength, making them suitable for edible film production due to their ability to form a gel-like structure, which is attributed to the presence of certain amino acids like proline and hydroxyproline. Taking into account the plentiful availability and affordability of thyme, oregano, and sage essential oils in our country, as well as the low cost of gelatin, this particular composition of film has yet to be extensively researched and could serve as a model for widespread implementation in the food industry.

In this study, we investigated the impact of various concentrations of thyme, oregano, and sage essential oils on thr properties of the resulting gelatin-based films. The study examined different concentrations of essential oil ranging from minimum 0% to highest 4% as the independent variable. The dependent variables included a range of physicochemical tests such as solubility, water permeability, thickness, opacity, and color parameters, as well as mechanical tests including elongation to breaking point, tensile strength, and Young's model. The study utilized a mixed experimental design known as simplex lattice and employed Design Expert13 software for experimental design, analysis of variance, diagram creation, and examining the interactions between variables.

In this research, the highest tensile strength (12 MPa), elongation at break point (26%) and Young's modulus (80 MPa) were found in high concentrations of oregano essential oil (4%). Among the treatments, the lowest solubility was in the high concentration of oregano essential oil in the mixture (4% area) and the lowest vapor permeability was in the area of low concentration of oregano essential oil in the mixture. The difference in the amount of turbidity of the resulting films was not significant, although it was the highest in the lowest concentration of oregano essential oil. The highest amount of thickness was obtained in the concentration of oregano essential oil in the region of 4%, which was statistically significant. By increasing the concentration of essential oil thyme in the mixture, the hue angle, whiteness index and saturation decrease, and its highest amount is in the area of 4% oregano and sage. The changes of a* and b* parameters have a trend similar to color indicators, but in relation to L*, the concentration of essential oils has no effect on the changes of this parameter.

The results of this research showed that adding a high concentration of oregano essential oil to the gelatin film compared to thyme and sage essential oils produced films with sufficient strength that have the highest efficiency and desirable characteristics compared to thyme and sage essential oils. It has a flower and can be used as a suitable coating for food protection by delaying the oxidation of lipids, mechanical properties and favorable color changes.

Dairy products are good sources of lactic acid bacteria (LAB). Proteolytic activity as one of the physiological properties of LAB plays important role in generating the aroma and taste of various cheeses, and reducing their ripening time. Therefore, the identification of multi functional strains can result in introducing novel cultures in order to manufacture the products with desired sensory properties and health-promoting effects. The aim of this study was to evaluate the proteolytic activity and probiotic properties of some LAB and their ability to produce aromatic compounds.

In this research, the proteolytic activity of three strains of Lactococcus lactis subsp. lactis, Lactobacillus delbruekii, and Lactobacillus fermentum was measured using the well diffusion method in Skim milk agar medium. Also, some safety properties including resistance to antibiotics such as erythromycin, penicillin, clindamycin, gentamicin, vancomycin, tetracycline, ampicillin and chloramphenicol, hemolytic activity and production of biogenic amines and a number of probiotic characteristics including cell surface hydrophobicity, auto-aggregation, co-aggregation and antimicrobial activity of these 3 strains were investigated. In addition, the ability to produce two aromatic compounds, diacetyl and acetylene, was evaluated qualitatively.

The diameter of the halos created as a result of the proteolytic activity of L. fermentum, L. delbrueckii and L. lactis subsp. lactis was 29.5, 25 and 15.7 mm, respectively. These strains were resistant to gentamicin and vancamycin and sensitive to chlorphenicol. The studied strains did not show any hemolytic activity and the ability to produce biogenic amines was not observed in them. In L. fermentum, L. delbruekii and L. lactis subsp lactis, the level of cell surface hydrophobicity was 83.33, 62.67 and 8.94%, respectively, and the auto-aggregation rate was 35.68%, 23.61% and 7.16% respectively. All three strains had a relatively high co-aggregation percentage with S. aureus S. typhimurium, L. monocytogenes and E. coli and showed a good antimicrobial effect on the studied pathogens. Also, the highest intensity of color resulting from the production of diacetyl and acetoin was observed in L. fermentum and L. delbruekii, respectively.

In this research, it was found that all three strains are safe and have good probiotic properties. In addition, due to their proteolytic activity, these strains are capable of producing the aromatic compounds of diacetyl and acetoin. In conclusion,, L. lactis subsp lactis, L. delbruekii and L. fermentum bacteria can be used as starter cultures to produce cheeses with a shorter ripening period and health-promoting potential.

Today, food allergies are increasing in different societies, and consumers have become more aware of food sensitivities, including allergies, and receive the necessary training. Recently, proposed food allergen labeling requirements in the European Union and the United States have increased awareness of food allergies among consumers, food manufacturers, and regulatory agencies. It is important to note that there is a lack of systematic and statistically valid data on true food allergies worldwide. It may also be underreported or simply undiagnosed in underdeveloped and developing countries. Considering that Asian countries constitute a major part of the world's population, the actual incidence of food allergies may be significantly higher than estimates and/or documentation. Therefore, efforts should be made to reduce food allergens.

Food allergens are almost always proteins. As studies have shown, protein denaturation and/or hydrolysis during food processing can be used to produce anti-allergenic products. According to the findings, food processing can affect the allergenicity of food proteins. Small allergenic proteins can be physically removed from some foods. In contrast, for larger proteins, enzymatic hydrolysis, chemical modification, or a combination of physical, chemical, and biochemical processes are often required to reduce or eliminate food allergenic genes.

As mentioned, food allergy is increasing and a global health concern. Among the measures thought to reduce food allergies, there are relatively effective food processing techniques, especially thermal and ultrasound methods that reduce the allergenicity of food proteins by changing structural epitopes through increasing cross-linking of proteins or they are useful by modifying linear epitopes through fragmentation. Also, more studies on the effects of food processing on the clinically relevant reactivity of food allergens in the body are necessary. This article is a short review on the effects of dry and wet heat process of food, irradiation, ultrasound, fermentation, proteolytic process, cold plasma, etc. in this field. In the following, examples of the effects of processes on the stability of food allergens are presented.Food processing can affect the sensitizing of food proteins. The extent of the effects depends on various factors, including the allergen and its biochemical and immunological properties, food matrix, processing conditions, thermodynamics of the allergen - IgE interaction, and patient sensitivity (threshold, tolerance and persistence of the allergen, allergic reaction to a specific allergen). To remove large allergenic proteins, enzymatic hydrolysis, chemical modification, or a combination of physical, chemical, and biochemical processes are often required to reduce or eliminate food allergenic genes. Protein oligomerization, as a result of the process, is considered one of the main contributing factors in the process of allergens. On the other hand, unstable oligomeric proteins may undergo dissociation into constituent polypeptides.Food processing can affect the sensitizing of food proteins. The extent of the effects depends on various factors, including the allergen and its biochemical and immunological properties, food matrix, processing conditions, thermodynamics of the allergen - IgE interaction, and patient sensitivity (threshold, tolerance and persistence of the allergen, allergic reaction to a specific allergen). To remove large allergenic proteins, enzymatic hydrolysis, chemical modification, or a combination of physical, chemical, and biochemical processes are often required to reduce or eliminate food allergenic genes. Protein oligomerization, as a result of the process, is considered one of the main contributing factors in the process of allergens. On the other hand, unstable oligomeric proteins may undergo dissociation into constituent polypeptides.

Dates, as a valuable and high-quality product, are the most important fruit in south of Iran. The quality of this fruit after harvesting and during the storage period, especially in the outside conditions of cold storage, may be changed due to biochemical and microbial interactions. The purpose of this research is to investigate the effect of cinnamaldehyde, sulfur dioxide, and ethanol in special multi-layer sachets on the quality characteristics of Mazafati during the storage period in cold and ambient temperatures. To conduct the experiment, cinnamaldehyde, and ethanol combined with bentonite and sodium metabisulfite alone were placed in special multi-layer sachets. Inside each package of Mazafati samples (~ 300 g) a sachet was placed in order to evaluate the quality characteristics (weight loss, pH, acidity, total soluble solids, peroxidase and catalase enzymes, microbial tests, and sensory evaluation) of stored samples in refrigerator and ambient temperatures. This research was studied using a factorial experiment based on randomized complete design with 5 treatments (cinnamaldehyde, sodium metabisulfite, and ethanol at 25°C and the control samples at 4 and 25°C) in 3 replicates. The changes related to weight loss, pH, acidity, and total soluble solids in the samples stored at 4°C were lower than the samples with releasing sachets; The highest changes were observed in control samples at 25°C (p<0.05). Among the samples treated with releasing sachets, the lowest pH and acidity changes were observed in the fruit samples treated with cinnamaldehyde and sulfur dioxide releasing sachets, respectively, also the lowest total soluble solids change was observed in the samples treated with sulfur dioxide releasing sachets and ethanol at the end of the storage period. peroxidase and catalase activity were higher in the samples stored at 4°C compared to other samples. Among the fruit treated with releasing sachets, the samples treated with sulfur dioxide and cinnamaldehyde releasing sachets respectively had more peroxidase and catalase activity than other samples. The counts of mesophilic bacteria and fungi of Mazafati samples stored at 4°C on the first day of storage were 2.8 and 3.4 log CFU g−1, respectively, which were significantly higher than the microbial counts of the samples stored at was 25°C (p<0.05). In the treated samples with ethanol, sulfur dioxide, and cinnamaldehyde the microbial populations were less than the detection limit. The panelists gave a lower score to the sample stored at 25°C due to the drier texture, sour taste and aroma at the end of the storage period, and the sample stored at 4°C received a higher sensory score. Among the samples treated with releasing sachets, the highest scores for aroma, taste, and overall acceptance were given to the sample treated with cinnamaldehyde releasing sachet. Storage temperature is an important factor that can affect the quality characteristics of Mazafati fruit during the storage period. In this regard, the least change of these parameters or in other words better preservation of quality characteristics was observed at 4°C. In general, among the investigated treatments and considering the cold storage costs, the use of cinnamaldehyde and sulfur dioxide-releasing sachets at 25°C storage, can be suggested to prevent microbial growth, reduce physicochemical changes, maintain quality characteristics, and ultimately the increase of Mazafati fruit shelf life.

The losses of horticultural products encompass both quantitative and qualitative losses from production to consumption. Three factors—harvesting time, storage, and climate—impact fruit quality and, consequently, lead to losses. Various indices are utilized to determine the proper harvesting time, with the most important ones for oranges being the maturity index (TSS/TA), total soluble solids (TSS), and extract content. Considering the weather conditions in each area, all these indices should be determined when the fruit is ripe. Additionally, fruit storage is contingent on production conditions such as climate, orchard management, harvesting time, and storage conditions. Due to the lack of necessary information about oranges produced in Golestan province, this research was conducted to determine fruit quality at harvesting time as well as after storage. In this study, considering the extent of citrus orchards and climatic diversity in Golestan province, the province was divided into three areas (west, Kordkoy and Bandarqs), center (Aliabad and Gorgan) and east (Azadshahr)..In each area some orchards with similar management were selected. Fruits were harvested from a number of trees in each orchard at two times (first half of the harvesting season, when less than 10% of the fruit surface discolored and the bottom half, when more than 90% of the fruit surface discolored). Then, samples from each area were mixed at each harvesting date and finally a mixed sample was obtained. Fruits were stored at 4-6 °C and 85-90% relative humidity. Characteristics related to fruit quality, such as titratable acidity (TA), total soluble solids (TSS), Maturity Index (TSS/TA), acidity, ascorbic acid, total sugar, reducing sugar and sucrose according to the method described by the Iran National Standards Organization (No 2685 and 14617-2) at harvesting time, after two and four months of storage Was examined. Data were analyzed by using factorial statistical design. The results showed that harvesting location had significant effect (p≥0.01) on TA and TSS as well as maturity index (p≥0.05) but had no significant effect (p≥0.01) on ascorbic acid, total and reducing sugar content. Harvesting time also affected TA, maturity index and ascorbic acid (p≥0.01) but had no effect on TSS, total and reducing sugar. Storage period affected qualitative characteristics of fruits included TA, TSS, maturity index, ascorbic acid and reducing sugar, except total sugar. The results showed that TA, ascorbic acid, TSS, maturity index, total sugar, reducing sugar and sucrose were in the range of 0.76-1.76 gram in100 mL juice, 11.4-40.16 milligram in100 gram juice, 8.88- 11.43 Brix, 6.34-13.34, 5.76-9.16 gram in100 gram juice, 3.01- 4.54 gram in 100 gram juice and 3.10-4.83 gram in100 gram juice, respectively. The fruits of the center of province had the highest amount of extract, total acid and lowest acidity, soluble solids and maturity index. The second harvesting time also reducing total acid and increased maturity index. The storage duration also increased the amount of extract, acidity, ascorbic acid, total soluble solids, maturity index and reducing sugar and decreased total acid and sucrose. Based on the results, it can be stated that samples from the center area should be picked up later than the other two sites to achieve better quality. Although storage duration had led to changes in some of the characteristics investigated, it can be stated that the fruit of the Golestan orchards had the potential of storage for four months.