ELECTRONIC JOURNAL OF FOOD PROCESSING AND PRESERVATION
Year:2020 | Volume:11 | Issue:2|Papers Count:11

Background and objectives: Increasing awareness about disadvantages of consuming fatty acids in dairy products has been led to increase in consumer demand for low-fat dairy products, including cheese. Low-fat cheeses are poor in taste and their texture is rubbery and hard. Therefore, in this study, the effect of adding sesame and walnut powders at the concentrations of 3%, 5% and 7% as alternative for fat in Cheddar cheese on physicochemical characteristics of Cheddar cheese was examined during 30 days of storage at 12 ° C. Materials and Methods: Seven treatments were designed along with two control samples which were low-fat and high-fat Cheddar cheese samples. The amounts of fat, protein, total dry matter, acidity and pH were measured. Texture hardness test was performed by texture analyzer. Fatty acid profile was determined by using gas chromatography (GC). Results: Both formulation and storage time had significant effects on physicochemical properties of Cheddar cheese samples. Just after production, it was found that the full fat control samples had the highest and the low fat control samples had the lowest amount of fat, also sample containing a mixture of 3. 5% sesame powder and 3. 5% walnut powder had the highest and full fat control sample had the lowest amount of protein content. At the end of the storage period, the highest and the lowest moisture contents were found in the low-fat control sample and the sample containing 7% walnut powder, respectively. Also, the highest and the lowest dry matter contents were observed in the samples containing 7% walnut powder and low-fat control sample, respectively. The highest and lowest acidity was related to full fat control and low fat control samples, respectively. Samples containing 5% and 3% sesame powder had the highest and lowest pH at the end of the storage period. The highest and lowest levels of hardness belonged to low-fat and high-fat control samples, respectively. The results of fatty acid profile showed that the samples containing walnut and sesame powder contained higher amounts of essential fatty acids than control samples. Conclusion: Among the tested samples, the treatment containing 7% walnut powder was identified as superior treatment for nutritional and qualitative characteristics due to its higher amounts of linoleic acid and linolenic acid and better sensory and textural properties which was close to full fat control treatment.

Background and Objectives: Thermal pasteurization destroys bioactive compounds. Therefore, there is a need for a technique that provides microbial stability and stability while preserving biologically active compounds in grape juice. In recent years, the application of ultra-sonication in food processing has been considered for its ability to deactivate microorganisms with very little or no effect on bioactive compounds and nutritional properties of food. Ultrasound is considered as one of the potential non-thermal pasteurization techniques in the production of juices and is an effective method for maintaining the qualitative properties of juices. These properties have the advantage of thermal pasteurization. The purpose of this study was to investigate the effect of thermal ultrasound in comparison with the usual pasteurization method on bioactive compounds and some characteristics of red grape juice (Brix, pH, acidity, vitamin C, phenolic content, antioxidant properties and anthocyanin content). Materials and Methods: In this research, the red grape juice was prepared from the fruit. The treatments were: controlled sample (without treatment), pasteurized sample (90 ° C, 30˝ ), heated sample at 60 ° C for 4, 8, 12 min, ultrasound sample without heating for 4, 8, 12 min with amplitudes of 24. 4, 42. 7, 61 μ m, ultrasound sample with heating (60 ° C) for 4, 8, 12 min with 24. 4, 42. 7 and 61 μ m amplitudes. The effect of treatments on Brix, pH and acidity, phenilic content, ascorbic acid content, antioxidant activity and anthocyanin content of the samples were investigated. Results: According to the results, the treatments did not have a significant effect on the pH, pH, and acidity of red grape juice. Pasteurization treatment caused the greatest reduction in the qualitative characteristics of the samples. The highest percentage of degradation of ascorbic acid content in red grape juice was 28. 2% which was related to pasteurization treatment, and high temperatures at 60 ° C and long duration also had the most significant decrease in ascorbic acid compared to other treatments. The highest phenolic content was observed in treatment with temperature of 25 ° C and duration of 4 minutes with intensity 61 μ m. The antioxidant activity of juice was significantly reduced by pasteurization and high temperatures with high levels. The highest antioxidant activity was related to treatment at 25 ° C for 8 minutes and 61 μ m intensity, which increased antioxidant activity compared to control sample of 16. 4%. Pasteurization treatment reduced 7. 4% of the anthocyanin content of red grape juice and at high levels of sonication, increasing the duration and treatment temperature had a negative effect on the content of anthocyanin and reduced it to 7. 9%. Conclusion: According to the results of this study, it can be stated that pasteurization treatment in most cases had a negative effect on the qualitative traits of red grape juice and by using thermosonication in producing red juice at lower temperatures than pasteurization, higher qualitative traits can be achieved. Therefore, the use of average values of ultrasound intensity (42. 7 μ m) at 60 ° C for red grape juice is recommended.

Background and objectives: In recent years, the use of lactic acid bacteria has expanded as protective cultures in the production of fermented products. A significant part of the antifungal activity of lactic acid bacteria is related to the metabolites produced by them, in particular the various organic acids. However, recently peptides and protein hydrolysates with antifungal activity have been produced. The aim of this study was to investigate the activity of isolates of proteolytic lactic acid bacteria in the production of fermented milk with antifungal properties. Materials and methods: In this study, sterilized skim milk was inoculated with single and combined cultures of Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus reuteri and Lactococcus lactis subsp. lactis (2%, w/w) and fermented at 37 ° C to reach the optimum pH 4. 5-4. 6. The peptide content and antifungal properties of fermented milk against Aspergillus niger, Penicillium expansum and Candida albicans were evaluated after fermentation and 7 days of storage in the refrigerator. Results: According to the results, Lactobacillus reuteri showed the least proteolytic activity in milk and among all the samples, the highest peptide content was observed in the fermented sample by combined cultures of all three isolates, resulting in the production of 62. 6 mg peptide per ml. Peptide-containing extract of fermented milk samples with combined cultures (S23 and S123) had the highest anti-mold activity with a MIC of 20 mg/ml. After 7 days of storage, the anti-mold property of sample S1 against Penicillium expansum and sample S2 against Penicillium expansum and Aspergillus niger increased with a MIC of 20 and 40 mg/ml, respectively. Also, all samples of fermented milk (zero time) retained anti-yeast properties after 72 h with a MIC of 40 mg/ml, which after 7 days of storage; this property was increased in fermented milk with single culture. Conclusion: During fermentation, the most proteolytic activity occurred in the sample fermented by a combination of three lactic bacteria. Peptide-containing extract of all fermented milk samples had anti-mold and anti-yeast properties, and most of the samples had a MIC of 40 mg per ml at zero time, although in some samples increased antifungal properties after 7 days of storage. In this study, it is likely to be a part of the antifungal effect of fermented milks may be due to their peptides generated during proteolysis.

Background and objectives: Surimi is mechanically deboned fish flesh washed with water or dilutes salt solutions and to which cryoprotectants have been added. Surimi is used as the raw material for preparation of seafood analogues, such as shrimp, crab legs, scallop and lobster tail. In conventional method, washing is one of the most critical steps for preparing surimi with good functional properties. Washing with water removes components that can have negative effects on gelation (e. g., sarcoplasmic proteins, although this is debatable) and compounds that can cause flavor, odor, stability and color problems. Various fish species are used as raw material for fish mince/surimi processing. In this study due to the limited sources of some white meat fish, the potential of dark meat fish such as Talang queenfish was investigated. Materials and Methods: Talang queenfish was purchased from the the dock in Bushehr. The Fish was manually deboned and has washed with cold water as follow: frequency of 1, 2 and 3 cycles for 5, 10 and 15 minutes. Then, NaCl was added (2. 5% w/w) and the samples were were chopped for 4 min at 4 º C to obtain a homogenous sol. The sol was then stuffed into a nylon casing with a diameter of 2. 5 cm and both ends were sealed tightly. Kamaboko gels were prepared by incubating the sol at 40º C for 30 min, followed by heating at 90º C for 20 min. All gels were cooled in iced water immediately. Prepared gels were stored at 4º C for 24 h before analyses. Results: An increasing trend in protein extraction, water holding capacity, hardness, whiteness and sensory parameters of surimi was observed when duration and frequency of washing increased. Conclusion: Washing (with water) was found to be suitable for the production of fishery products (such as fish ball, Fish fingers and. etc) from dark meat fish, because the taste and smell of fish get better. For cost and time management it is also suggested to use chemicals in water for washing the surimi produced from Talang queenfish.

Background and Objectives: Most of the vegetable oils are liquid in the room temperature. Investigations about novel structuring methods of liquid oils are necessary due to the need of food industry to texturized fats with plastic and semi-solid texture in ambient conditions. There are different methods to produce semi-solid fats including, hydrogenation, blending, and interesterification. The mentioned methods have some advantages or disadvantageous. In the vegetable oil industry, there is the desire to use new methods of producing texturized fats. Oleogels obtained from vegetable oils using polymer and surfactant is an alternative for common structuring ways, with the aim of reducing saturated and trans fatty acids intake through the diet. Materials and Methods: In this study, oleogels with six different formulas were prepared. The first 3 ones were made with sesame oil (80, 85 and 90%) and ethylcellulose (10, 15 and 20%); the others were prepared with the same oil contents and the mixtures of ethylcellulose and polyglycerol polyricinoleate, 3: 1. Atomic force microscopy was utilized to image the microstructure of the oleogels. Fatty acid profile of prepared gels was determined by gas chromatography. The oleogels were stored at different conditions (ambient temperature and refrigerator). Their peroxide and thiobarbituric acid values were determined after production and every 30 days during 2 months storage. Results: The investigation of apparent properties showed that by the increase in ethylcellulose concentration, the strength of gel network was increased. PGPR addition to formulations resulted in increased plasticity and decreased the stickiness of the gels. Microscopic images showed an organized network of ethylcellulose strands which trapped liquid oil. As ethylcellulose concentration increased, continuous network of polymer strands was formed. A decrease in thickness of ethylcellulose strands was observed upon PGPR addition and more homogenous and uniform gel network was formed. Results showed no significant differences between the fatty acid profile of sesame oil and its oleogels. In shelf life studies, by increasing concentration of ethyl cellulose, peroxide values of prepared oleogels tended to decrease. Peroxide and thiobarbituric acid values of the oleogels were increased during storage conditions. The oleogels in the refrigerator had lower peroxide values. Further research is needed to understand secondary oxidation process of the oleogels. Conclusion: As a general result, it is possible to produce food-grade oleogels from sesame oil, ethylcellulose, and PGPR. It seems such gels have a great potential to use in the formulation of texturized fats and margarines and they are healthy alternatives for various types of hydrogenated oils.

Background and objectives: Cake is one of the most important and high-quality cereal products. Because of high fat and sugar content in the formulation, its long consumption may results in obesity and some health problems. One option to produce more healthy food products is to remove some of the energy-rich compounds, such as sucrose, or to replace it with other non-energy or low energy sources. Materials and Methods: The treatments included the samples containing 100% of sucrose (C), 50% of sucrose with 50% of erythritol and sucralose (M), 50% of sucralose and 50% erythritol (SE), 100% of erythritol (E) and 100% of sucralose (S). Then the dough samples were subjected to rheological tests and the produced breads were subjected to physical, chemical and organoleptic tests. Results: According to the results, the control and M samples had the highest (2. 35 and 2. 19 g/cm3), but the sample E had the lowest density (1. 29g/cm3) (P≤ 0. 05). The sample E had the highest (39. 93Pa. s), but C, M, SE and S treatments had the lowest viscosity (P≤ 0. 05). According to the results, the highest moisture contents (27. 11 and 26. 72%) were observed in the control and M but the lowest moisture content (20. 20%) was measured in S treatment (P ≤ 0. 05). Also, the highest amounts of fat (20. 02 and 19. 59%) were observed in E and S treatments, while the lowest (18. 46%) in treatment C. According to the results of mean comparisons, E, S and SE treatments contained the highest amount of ash (0. 88, 0. 85 and 0. 83%) and protein (10. 14, 9. 93 and 9. 79%), respectively. After that, M and control treatments had the lowest amount of ash (0. 75 and 0. 70%) and protein (8. 78 and 8. 25%). The sample E had the highest amount of luminance (L*= 55. 65), while the sample C had the lowest amount (L*=46. 15) (P ≤ 0. 05). In the same way, the treatment C had the highest amount of redness (a*=2. 22), yellowness (b*=33. 52) and total color difference (Δ E = 7. 4), but the treatment E showed the lowest amount of redness (a*=1. 1), yellowness (b*= 21. 54) and total color difference (Δ E=1. 2)(P≤ 0. 05). Moreover, the highest volume (910. 32cm3) was observed in control sample while the lowest volume (551. 26cm3) was observed in SE treatment (P≤ 0. 05). Meanwhile, the highest (6400 calories) and the lowest amount of energy (1500calories) were measured in control and S treatments (containing 100% sucralose), respectively. According to the results, in the first, third and seventh days, the highest degree of staling were found in treatments E (26. 517N) and S(26. 446N), but its lowest amounts were observed in treatments C (9. 908N) and M (10. 25N) (P≤ 0. 05). In addition, the control and M treatments had the highest score of texture and structure (8. 6), chewiness (9), taste and flavor (9), porosity (9), apparent shape and form (8. 8) and freshness (6). Notably, no significant difference was observed between all treatments in terms of properties of crust and crumb (P>0. 05). Conclusion: According to the results of physicochemical, rheological, staling and sensory tests, the sample containing 50% erythriol and sucralose and 50% sucrose (M) showed the highest similarity to the control treatment in terms of different properties such as density, dough viscosity, moisture content, ash, protein, and staling (sensory and instrumental) and all sensory properties, and therefore is recommended as the best treatment.

Background and objectives: A considerable amounts of Fruits and vegetables is lost during the post-harvest stages. One of the most important processes that reduces fruit loss and extends their shelf life is pre-cooling. In this process, biological activities of the products are decreased rapidly. The aim of this study was designing and constructing the forced air pre-cooling system for horticultural products. Material Martials and methods: In this study, the forced air pre-cooling system of horticultural products was designed and constructed according to the industrial pattern. To evaluate the performance and uniformity of cooling process in the system, the precooling of Peach was performed using fruit pallets with the three kinds of packages namely one-row package, two and three-row packages. In addition, the airflow rate was evaluated in three levels consists of 0. 5, 1 and 1. 5 liters per second per kilogram of product. Results: The evaluation of results indicated that the air velocity field was uniform around the constructed precooling system with cross section dimension of 550×1200 mm and the height of 2050 mm. The suction fan power was 0. 5 hp and the cooling capacity of the system about zero º C. Therefore, all fruits located in the different location of pallet were cooled with an acceptable uniformity viewpoint of the cooling time and temperature. Also, the standard error of cooling time was not significant. Among the studied factors, the effect of airflow rate on the average 3/4 th cooling time of fruits in different boxes in the pallet and their standard deviation were significant. Increasing the airflow rate decreases the cooling time and improves the uniformity of cooling between the various packages, so that with three times increasing the airflow rate, the standard deviation decreases 59%. According to the results, the kind of package had a significant effect on the average 3/4 the cooling time of fruits and the minimum and maximum cooling time were related to the three rows and two rows boxes, respectively; but its effect on the standard deviation was not significant. Conclusion: The developed precooling system could create and distribute of cold air uniformity between the fruits boxes in different locations of the pallet. There were no significant differences between the cooling time of fruit in both airflow rate of 1 and 1. 5 lit s-1 kg p-1. Also, the rate of energy consumption is considerable in the high airflow rates. Therefore, it is recommended usage of cold airflow rate of 1 lit s-1 kg p-1. Although the three rows box had the lowest cooling time, due to the mechanical damage probability, it's using had no advantage as compared to one-row box.

Background and objectives: Many of the biological functions of jujube fruit could be due to its antioxidant compounds. However, antioxidants and antioxidant capacity of fruits could be affected by several factors, such as cultivar, agronomic condition, postharvest manipulation, and maturation of fruit. The aim of the present study was to optimize the conditions used in extraction of aqueous extract from jujube cultivated in Iran, as well as comparing amounts of jujube bioactive compounds with both hydroethanolic extract and literature. Materials and methods: Response surface methodology was used to determine optimal amounts of independent variables, namely liquid-to-solid (L/S) ratio (v/w), extraction period, and temperature. Therefore, The samples were extracted using water, in well-sealed flasks with different L/S ratios ranging from 10: 1– 40: 1 for specific extraction periods ranging from 30– 300 min, where the temperature of the extraction medium ranged between 30 and 70 oC (within ± 1 oC) under constant stirring, (250 rpm). Finally, the responses, including total extraction yield, total phenol content (TPC), total flavonoid content (TFC) and IC50, determined in optimal extract was compared with those determined in hydroethanolic extract or BHT synthetic antioxidant. Results: The TEY, TPC, TFC and IC50 in the extracts from HAE process were ranged from 50. 48 to 77. 97%, 8. 23 to 14. 38 mg GAE/g of extract dry weight, 1. 42 to 3. 93 mg Quercetin equivalent/g of extract DW), and 16911. 6 to 34021. 3 μ g/mL, respectively. The optimum HAE conditions included an extraction time of 30 min, temperature of 66. 88 ° C, and 40: 1 liquid-tosolid ratio, resulting in the maximum TEY (77. 67%), TPC (13. 93 mg/g), TFC (4. 56 mg/g) and minimum IC50 (21577 μ g/mL). When aqueous ethanol (60%) was used as solvent during extraction process, 1. 22-, 2. 65-and 1. 45-fold increase were observed in the amounts of TPC, TFC and antioxidant capacity, respectively. the radical-scavenging activity (free radical inhibition percentage) of the optimum jujube extract at concentration of 10000 ppm (33. 08%) was found to be approximately equivalent to that measured for 500 ppm concentration of BHT (35. 57%). Conclusion: High levels of bioactive compounds were detected in the aqueous and hydroethanolic extract from jujube. These extracts are not suggested to be used as alternative for synthetic antioxidants due to their low levels of antioxidant capacity, as well as contradictory reports for jujube antioxidant capacity which is changed depending on fruit ripening and postharvest condition. However, the jujube fruit flour or extracts could be used as functional additive in enrichment of food products.

Background and objectives: Tragacanth gum (GT) is one of the natural secreted hydrocolloids which has many applications in food and pharmaceutical industries. Unfortunately, there is limited scientific information about the electrostatic interactions of tragacanth gum with proteins, especially the proteins unfolded by physical approaches. In this regard, the main objective of this study was to investigate the effect of thermal processing on the whey protein isolate (WPI) properties and its complexation with tragacanth gum. Materials and methods: The influence of heating time (0, 5, 10, 15, 20, 25, 30 and 35 min at 80 C) on the turbidity of WPI, alone and mixed with GT (r = 0. 1, pH 4. 0 and Cp 0. 1 w/w) was surveyed. Then, the flow behaviour and viscosity of GT-WPI mixture at a shear rate of 0-100 S-1 (pH 4. 0) was compared with the individual solutions of gum and protein. Since the maximum turbidity was observed in the range of 15-35° C, the impact of heating time at three levels (15, 25 and 35 min) and biopolymer mixing ratio at six levels (2: 1, 1: 1, 1: 2, 1: 5, 1: 10 and 1: 20) on the protein and carbohydrate compositions of precipitate and supernatant was investigated by Lowry and phenol-sulphuric acid methods, respectively. Results: Turbidity of protein solutions significantly changed with rising the heating time such that the maximum turbidity achieved after 25 min thermal processing. While these solutions were unstable due to protein-protein interaction and formation of protein aggregates, GT addition led to significant changes in the stability of protein solutions as a result of protein-polysaccharide interactions. Similar to protein solutions, the maximum turbidity of the complexes was achieved after 25min thermal processing. The rheological measurements showed that the mixture solution had pseudoplastic behavior with a large hysteresis loop as well as the higher viscosity rather than the blank solutions, indicating the formation of electrostatic interactions between protein and polysaccharide. By determining protein and polysaccharide content in the supernatant and precipitate phases, the least ratio of Pr: PS was observed for the 25-min heated WPI. Furthermore, the ratio of Pr: PS in the precipitate was increased significantly as Pr: PSratio was increased in the mixture. Conclusion: Addition of tragacanth gum to the whey protein isolate led to a significant stability in the solution. Due to unfolding of WPI, using thermal processing on the whey protein isloate solution resulted in a meaningful increase in the turbidity of protein solution and the efficiency of GT-WPI complex formation.

Background and objectives: Button mushroom has short shelf life because of its high sensitivity to physical damage. There are a large number of researches on different methods of drying and combined methods of osmotic dehydration and air drying. There is less information about using salt solution as osmotic solution and the effect of ultrasound on dehydration rate of Button mushroom. Aiming to achieve the optimum method of osmotic dehydration, the effect of osmotic processing conditions on mass transfers was investigated in the present study. Materials and methods: In the first step, osmotic dehydration process was carried out by immersing samples in different sodium chloride concentration 6, 9, 12 and 15%, for 20, 40, 60, 90 and 120 minutes at 25° C and 45° C and water loss, solid gain and weight reduction was studied. Results: The results showed that, WL and WR increased with osmotic of solution concentration, temperature and immersion time. Higher osmotic solution concentration used in osmotic dehydration resulted in greater mass transfer. When immersion time was increased to 60 min, despite the osmotic solution become diluted because of water entering the solution and moisture diffusion increased. The effect of increasing the solution temperature of a highly concentrated solution on mass transfer was attributed to a decrease in the viscosity of osmotic solution, resulting in high diffusion rates for both water and solids. But in this process, at temperature of 45 ° C, greater the mass transfer rate achieved, mainly due to the increase in cell permeability and permeability coefficient. It was found that salt concentration of 12%, immersion time of 60 min and temperature of 45° C gave maximum water loss (29. 36%) and weight reduction (24. 53%). Conclusion: Osmotic process can be used for dehydration of vegetables by placing them in a salt solution. Osmotic dehydration can be used as an effective method of preservation to produce high quality products with lower thermal degradation and to reduce the energy requirements.

Background and objectives: The oil oxidation changes the organoleptic characteristics of foods and decreases the nutritional value and shelf life of oils and is harmful to consumer health due to formation of unfavorable compounds in oil. Currently, the most widely used antioxidants are synthetic antioxidants, but their use faced some restriction due to their carcinogenic properties. Hence, natural antioxidants such as tocopherols and ascorbic acid derivatives are widely used as safe natural antioxidants. The aim of the present study was evaluation of antioxidant properties of date palm and Zizyphus extracts and their combined extract on soybean oil oxidation. Materials and methods: In this research, initially the antioxidant effect of individual and combined aqueous extract of the zizyphus fruit and date seed in different concentration was measured and then the effect of the zizyphus fruit and date seed extracts and their selected combination based on previous step, on oxidative stability of soybean oil during storage was evaluated. For this purpose, the extracts were added to free antioxidant soybean oil and oxidative stability of oil was measured at temperature of 63 ° c for 32 days using peroxide index, the induction period and also thiobarbituric acid index (TBA) and was compared with synthetic antioxidant BHT. The treatments used in antioxidant experiment were the individual and combined extract of the zizyphus fruit and date seed at two different concentrations of 200 and 500 ppm with different ratio of combined extract including 0: 100, 20: 80, 40: 60, 50: 50, 60: 40, 80: 20 and 100: 0. In the soybean oil stability experiment the treatments used were ratio of the combined zizyphus fruit and date seed extract of 20: 80 at concentration of 200 ppm and two concentrations of 200 and 500 pp for individual extract and BHT in two concentrations of 100 and 200 ppm. The results were compared in three replications using the completely randomized design, in a factorial design experiment, ANOVA analysis and Duncan test (p < 0. 05) by SPSS software (version 16) and the graphs were drawn by Microsoft Excel. Results: The results of the peroxide value and TBA tests showed there was no synergistic effect in the combined extract (zizyphus fruit: date seed with the ratio of 20: 80, in concentration of 200 ppm). Yet in peroxide test this extract showed a significant better effect (p < 0. 05) compared to BHT, but in TBA test, it showed similar function as synthetic antioxidant BHT. In individual extract at both concentration of 200 and 500 ppm they were comparable to BHT with the concentration of 100 and 200 ppm. Conclusion: Results of present study indicates the zizyphus fruit and date seed extracts, as individual or combined extract could be used as an alternative to the synthetic antioxidant BHT.