ELECTRONIC JOURNAL OF FOOD PROCESSING AND PRESERVATION
Year:2019 | Volume:10 | Issue:2|Papers Count:10

Background and objectives: Date palm fruit (Phoenix dactylifera L. ) is an important agricultural product in Iran. Date is a good source of energy and rich in nutrients. Amongst several important varieties of dates, Mazafati in terms of marketability and consumption in Iran is placed in first rank. Because of unsuitable storage conditions and poor packaging, fruit quality changes during storage and so the product turns sticky and hard due to the syrup exudation and moisture loss. To overcome this problem, application of edible coatings would be a proper suggestion. Edible coatings have been widely studied in the last years because of their proven beneficial effects on fruits and vegetables shelf life. The use of edible films and coatings has many functional advantages such as modification of fruits metabolism by affecting respiration rate, prolonged storage life, firmness retention, and controlling the microbial growth. Different kinds of polysaccharide, protein, lipid and composites are used as the films and coats. Lipidbased films have good water vapor barrier properties, due to their low polarity. Also, temperature is one of the most important factors, which affects the shelf life and the quality of date fruits. The purpose of this research was to study the effect of lipid based edible coating (glyceryl monostearate and carnauba wax) and storage temperature on quality of Mazafati date fruit. Materials and methods: In this research Mazafati date fruit was coated with lipid based coatings (glyceryl monostearate and carnauba wax) and stored at 4 and 25 C° for 3 months. During storage, weight loss, hardness, titratable acidity, total soluble solids (TSS), reducing sugars, color (lightness, redness and yellowness) and sensory properties (color, texture, flavor and total acceptance) of date fruit were evaluated. The experiments were performed in factorial experiments on a completely randomized design. The edible coating, temperature and storage time were the independent variables. Analysis of variance (ANOVA) was conducted using SPSS 21 software. Comparisons among the mean values were also determined using Tukey test (p<0. 05). Results: The results showed that the coating was effective in decreasing the weight loss and the rate of change in titrable acidity and color, as well as sensory properties of date fruit. The coated date fruits had more titratable acidity compared to the control. Although no significant difference was found for hardness, titrable acidity, total soluble solids and reducing sugars contents, but carnauba wax coat was more effective to maintain color and sensory properties. The used edible coating resulted in increasing lightness, yellowness and sensory scores of date palm significantly. Increase in the storage temperature caused the increased weight loss and decreased yellowness significantly. Increasing storage time also caused the increase in hardness, redness and decrease in lightness and sensory scores. At the end of storage time, the least value of weight loss and the highest value of yellowness (8. 13% and-0. 84, respectively) were found for the samples coated with glyceryl monostearate stored at 4 C° . Also, the highest value of lightness and total acceptance score and the least value of redness (17. 2, 3. 1 and 3. 99 respectively) were obtained for the samples with carnauba wax coating. Conclusion: The use of lipid based edible coating and low temperature storage could delay changes in physicochemical and sensory properties of date fruit and increase the shelf life of Mazafati date fruit.

Background and objectives: Lipid oxidation is one of the most important reasons for decrease in nutritional quality and organoleptic properties of foods as well as the development and progression of various diseases through the formation of free radicals. Hence, the use of antioxidant compounds to protect foods against oxidation is essential. Nowadays, extensive studies were carried out on exploration of natural and safe antioxidant compounds due to consumers concerns about safety of synthetic ones. Therefore, in this study, the protective ability of green pea pod extract as a plant antiradical agent against oxidation of sunflower oil was investigated. Materials and methods: At first, green pea pod extracts were obtained using water, ethanol, acetone and hexane. Total phenolic content (TPC) and antiradical activities of extracts were assessed using colorimetric method, and DPPH and H2O2 radical scavenging activity test, respectively. Then, the effect of green pea pod extract containing the highest amount of total phenolics and maximum antiradical ability on oxidative stability of sunflower oil under accelerated conditions at 65 º C for 24 days were evaluated through peroxide, p-anisidine and TOTOX values. For this purpose, green pea pod extract at five different concentrations (200, 400, 600, 800 and 1000 ppm) and the synthetic antioxidant of BHT (200 ppm) were added to sunflower oil. Results: The highest TPC (140. 4 mg GAE/g) and DPPH and H2O2 radicals scavenging activity (82. 47 and 10. 63%, respectively) was obtained for ethanolic bioactive extract from green pea pod. For control sample, the maximum values of peroxide, p-anisidine and TOTOX were 185 meq O2/kg oil, 37 and 407 after 24 days under accelerated conditions. While these values were 128. 2 meq O2/kg oil, 28 and 208 for the oil containing the lowest concentration of green pea pod ethanolic extract. The results revealed that addition of green pea pod ethanolic extract at a concentration of 1000 ppm in sunflower oil was more effective than BHT (200 ppm). Conclusion: The results obtained confirmed the suitability of green pea pod bioactive compounds antiradical activity especially for ethanolic extract. On the other hand, stability of sunflower oil seems to be difficult due to the high amount of linoleic acid but the results revealed that ethanolic extract of green pea pod was able to protect sunflower oil against oxidation as well. As a result, green pea pod ethanolic extract could be suggested as a natural and effective alternative for BHT in order to increase oxidative stability of sunflower oil.

Background and objectives: Organic black grapes produced in Sardasht, West Azerbaijan province in Iran, contain resveratrol and flavonoids and high amount of melatonin with health benefits. The relationship between equilibrium moisture content and water activity at specified temperature is expressed as sorption isotherms. Moisture sorption isotherms are useful in predicting shelf-life stability and in calculating the variations of moisture content during drying, storage and packaging. In physical, chemical and microbial analysis of food, data obtained from adsorption and desorption curves are very important factors. Isotherm curves are able to predict the maximum moisture retention in foods during processing. In this study, the moisture sorption isotherms of grape pulp (Siah-Sardasht cultivar) were determined using a static-gravimetric method at 30, 40, 50, 60 and 70° C with water activities over the range of 0. 1-0. 9. Material and methods: Black grapes were obtained from a vineyard in Sardasht (West Azerbaijan province). Nine saturated salt solutions with degree of purity over 98% were used for generating a range of relative humidity. In order to describe the sorption moisture isotherms, the BET, GAB, Henderson, Darcy-watt and Halsey equations were tested to fit the experimental data by using non-linear regression analysis method. The models were sorted based on the least mean absolute percentage error (P<10%), RMSE and χ 2, and the highest R-square. The isosteric heat was determined using the Claussius– Clapeyron equation. Results: At all of temperature levels, moisture sorption isotherm curves of grape pulp were of type III, according to BET. Moisture sorption isotherms obtained in this work were affected by temperature, and the equilibrium moisture content generally increased with temperature elevation. According to the evaluated parameters in the tested models, P-value of Darcy-Watt model was consistently less than 10 % and its RMSE and χ 2 were lowest, indicating its reliability in predicting moisture sorption behavior of grape pulp. According to results of predicting moisture sorption in the grape pulp, it is concluded that BET and GAB models can be used only at high temperatures. The isosteric heat showed a marked increase with decreasing moisture content especially at the levels less than 0. 3% (d. b). Conclusion: At the studied range of water activity, the equilibrium moisture content values of grape pulp increased with increasing temperature, and no reverse temperature effect was observed in the range of water activities studied here. In spite of presence of sugar in the black grape pulp, no inversion phenomenon was observed in the relationship between equilibrium moisture content and water activity. Darcy-Watt was found to be the best model offering fits over the entire water activity and temperature range. The isosteric heat decreased with increasing the moisture content probably due to the fact that pulp water properties approached to that of free water.

Background and objectives: Dry ice cream is a traditional Iranian product manufactured by boiling and concentration of milk with the addition of sugar and shortenings. However, it can be reproduced as a new dairy product by using new processing methods. This research is the first scientific study on dry ice cream. The aim of the current research was to study the effects of storage temperature on quality and shelf life of dry ice cream. Materials and methods: Dry ice cream was prepared by adding milk, sugar, glucose syrup and shortening and packed in conventional cardboard boxes. Then, all the samples were kept in three different temperatures (-18, +8 and +28 ° C) for 60 days. The qualitative characteristics were investigated by performing physico-chemical tests including determination of moisture content, fat, protein, ash, pH, acidity, acid number and peroxide value, texture firmness, total count of aerobic microorganisms and yeast and mold, and sensory evaluation. Completely random design was used for statistical analysis. Results: The amount of carbohydrate, moisture, protein, fat and ash of dry ice cream was 77. 60, 14. 16, 4. 76, 2. 48 and 1. 00%, respectively. By passing time and increasing storage temperature, moisture content, pH and scores of sensory features decreased, but acidity number, peroxide value, firmness, total count and mold and yeast count increased. The highest and lowest rate of increase in peroxide values were observed in samples stored at +28 ° C and-18 ° C, respectively. The total count of microorganisms in the samples stored at +8 and +28 ° C increased during storage, but, on the contrary, decreased significantly at-18 ° C on day 60 compared to the first day. In the samples kept at-18° C, except for the first day, no mold and yeast growth was observed during storage. In contrast, the mold and yeast count increased in the samples stored at + 8 ° C and + 28 ° C. On the other hand, the scores for sensory evaluation of all samples showed a decrease during storage, as the highest and lowest reduction in points was found in the samples stored at-18° C and 28 ° C, respectively. Conclusion: According to the results and regard to quality and shelf life evaluated here,-18 ° C and +28 ° C were the most suitable and unsuitable temperatures for storing dry ice cream, respectively. In addition, storing at-18 ° C up to 60 days, +8 ° C up to 20 days and +28 ° C up to 5 days, showed the best sensory features.

Background and objectives: Flixweed (Descurainia sophia L. ) is an annual plant that is found in various parts of the world including Iran. Flixweed seed and its prepared drink (Sharbatekhakshir) have been traditionally prescribed as a remedy for diarrhea, heatstroke, palpitation, upset stomach, impotence, intestinal inflammation, constipation, skin eruptions, laxative, and antipyretic since the ancient times. Despite the unique medicinal and nutritional advantages, Flixweed drink production is faced with two major technological problems; first, it is not suitable for diabetics because of the high amounts of sugar in the drink formulation. On the other hand, sedimentation of flixweed seed in the prepared drink is the other common problem that restricts its commercial production. The aims of this study were investigating the possibility of replacing sugar with grape syrup as a natural sweetener to producing functional drink and the possibility of stabilizing the flixweed drink using soluble soybean polysaccharide and xanthan gum as natural hydrocolloids. Materials and methods: The first step for producing the functional flixweed drink was to examine replacing sugar with grape syrup in various ratios (0: 100, 10: 90, 80: 20, 70: 30, 60: 40, and 50: 50). Then, in order to stabilize the flixweed drink, the effect of various concentrations of xanthan gum (0. 1, 0. 2, and 0. 3 % w/v) and soluble soybean polysaccharide (1, 2, and 3 % w/v) was studied. For pasteurization, samples were heated in 80 ° C for 1 min, and then cooled to 7 ° C. Then, different properties of the prepared (Brix, pH, phase separation, colour, rheological and organoleptic properties) were analyzed and compared to each other. Brix and pH were calculated using refractometer and pH meter, respectively. Stability of samples was investigated according to phase separation after 30 days of storage in the refrigerator. Color characteristics including lightness (L*), Redness (a*), yellowness (b*), browning index (BI), and caramelization (Hue) were evaluated by means of Konica Minolta CR-400 apparatus. Rheological properties of the prepared were measured by Ultra DV3-LV Rheometer. Organoleptic features of samples such as color, flavor, odor, fluidity, mouth feel, and overall acceptability were evaluated by 10 trained panelists. The experiments were conducted in a completely randomized design and mean values were compared using Duncan method at P<0. 05. Results: According to the results, the optimum ratio of grape syrup to sugar was 40: 60 in flixweed drink. The best formulation for flixweed drink was composed of 5% seed, 6% sugar, and 4% grape syrup. The Results revealed that the addition of xanthan gum and soluble soybean polysaccharide had no significant effect on pH and Brix. In addition, soluble soybean polysaccharide showed no effect on the stability of prepared drink, while xanthan increased the stability. The use of xanthan gum at 0. 3% concentration completely prevented the phase separation after 30 days of storage. The most appropriate model for both the control and samples containing soluble soybean polysaccharide was Newtonian model, while a pseudoplastic model was found to be suitable for drink containing xanthan gum. According to the results of colorometric tests, lightness, redness, yellowness, caramelization and browning indices increased after pasteurization. The sensory characteristics of stabilized drinks were found to be very similar to those of blank samples. Conclusion: In overall, it could be concluded that grape syrup and xanthan gum can be used for manufacturing the functional and stabilized Flixweed drink with good organoleptic attributes.

Background and objectives: Camel milk and its products have different physicochemical properties from those of cow's milk. The present study was aimed to investigate the feasibility of production of a functional ice cream from camel milk by application of resistant starch (RS), Arabic and xanthan gums. The resultant ice creams were evaluated in terms of their physicochemical, rheological, textural and organoleptic properties. Materials and methods: In this research work, maize RS, Arabic and xanthan gums were used as stabilizers in ice cream formulation. Different ingredients including skim milk powder, stabilizer-emulsifier, sugar, and vanilla were mixed to set the dry matter of camel milk ice cream on 30%. To prepare one kilogram of ice cream mix, camel milk was mixed with 160 g sugar, 3 g stabilizer-emulsifier, 1 g vanilla powder, and RS or gums; then the dry matter was adjusted to 30% by using skim milk powder. Ice cream mix was pasteurized at 68 ° C for 30 min and then aged at 4 ° C for 24 h. The aged mix was then frozen using a laboratory ice cream machine. Ice cream samples were evaluated for their textural and rheological characteristics. Results: The least overrun value (28. 02%) belonged to the sample containing the maximum amount of gums and RS, while the control sample had the highest overrun (50. 75%). Ice cream mix prepared with the maximum amount of RS showed the highest viscosity, while the control sample had the least viscosity. The least (22. 02%) and highest (52. 63%) melting rates belonged to the samples containing the maximum amounts of RS or gum and control sample, respectively. Xanthan and Arabic gums and RS were significantly affected by the first dripping time in the linear parameter. Both gums showed a significant effect on hardness and adhesiveness (p<0. 01), while RS had no significant effect on adhesiveness (p>0. 01). Results for the fitting of rheological behavior of ice cream mixes showed that the Herschel-Bulkley model could predict the behavior of fluid with a high correlation coefficient. Sensory properties of camel milk ice creams were significantly improved by increasing the amounts of xanthan and Arabic gums. Results of formulation optimization revealed that the best amounts of RS, Arabic and xanthan gums were in the range of 0. 48-0. 5, 0. 6, and 0. 23, respectively. Conclusion: It was concluded that maize RS, Arabic and xanthan gums had a significant effect on physicochemical properties of camel milk ice cream. These ingredients have the potential to be used as stabilizers in ice cream formulations.

Background and objectives: Fruit Juice has great nutritional value and rich in antioxidants and essential minerals for human health. Different processes such as heat treatment, freezing, cooling and in some cases clarification and filtration are applied for the preparation and preservation of juices. In clarification, the suspended solids and colloid compounds are removed from the solution system. In chemical clarification methods (classic method), different types of enzymes (pectinase, amylase, protease, etc. ) and finning compounds such as gelatin, bentonite, and silica gel or combination of these agents are used. Classic methods are expensive and timeconsuming, and it is difficult to remove the mentioned added materials. In the recent years, membrane filtration has been proposed as a new processing method. The use of membrane filtration is a good way to overcome juice turbidity. In addition, by using membrane filtration, higher stability and lower microbial contamination will be gained in the final product in comparison to conventional methods. In this study, the effect of membrane parameters including pressure (1. 2-2. 2 bar) and temperature (25-35 º C) on the viscosity, density and color indices (L *, a *, b *, total color difference, chroma and browning index) of sour orange juice during membrane clarification was investigated. Materials and methods: UF membrane was used for the clarification of sour orange juice. Physicochemical tests were performed according to Institute of Standard and Industrial Research of Iran (2685) methods. Viscosity was measured by using rotational Brookfield viscometer. Image processing method was used for tracing color changes after the process. Response surface methodology with central composite design was employed to predict the impact of UF process variables (temperature and operating pressure) on the rheology and color of sour orange juice. Data analysis was performed using Design-Expert 9. 0. 0. 7 software. Results: Results showed that by increasing temperature, the browning index, viscosity and density increased, but L* and TCD decreased. The browning index, chroma and viscosity decreased by increasing the pressure, but L*, b* and TCD increased. Effect of temperature and pressure on a* index was not significant. Linear and quadratic models were the best models to predict density, TCD and to predict L *, b *, BI and Chroma, respectively. Conclusion: The use of membrane processes improves the quality (color) of beverages and fruit juices. The membrane filtration showed good performance in sour orange juice clarification.

Background and objectives: Proteins are one of the most important compounds that besides nutritional values have a crucial role in food texture development. Proteins are the basic structure of acid-induced gels such as yoghurt. The extent of protein interactions and the resulted molecular construction determine the texture and strength of a gel. An effective strategy to improve textural properties of food proteins particularly dairy products is enzymatic treatment with transglutaminase (TG). TG develops a stable and smooth gel with higher water holding capacity through formation of covalent bonds between milk proteins and trapping water in protein network. Nowadays, different methods including the enhancement of total solids (e. g. addition of milk powder) are used to improve the yoghurt texture. However, such treatments would results in higher acidity in the product during storage period. It seems that by using TG enzyme, not only the yoghurt texture can be improved, but also the reduction of quality of the product during storage time can be prevented. Materials and methods: Set-type yoghurt samples were manufactured from cow's milk treated with different concentrations of microbial TG (0. 01, 0. 02 and 0. 03 percent TG per milk, v/w) and different amounts of dry matter of milk (8 and 9%). A yoghurt sample without added TG was regarded as the control. Fresh and stored yoghurts (during 21 days) were evaluated for sensory attributes (appearance, color, odor, texture and taste) and instrumental texture analysis (hardness, consistency, adhesiveness and viscosity index). Results: Results showed that all variables had significant effects (p<0. 05) on the studied parameters. In general, , all the sensory parameters, except for color and taste, were affected by the variables, i. e. milk powder addition, TG treatment and storage period. By increasing the variables levels, particularly by increasing enzyme concentration, the appearance and texture of yoghurts were improved. The results also showed that by increasing enzyme concentration and milk solids, the amount of hardness, consistency, adhesiveness and viscosity index were considerably increased. In all the yoghurt samples, the hardness and consistency reached to the maximum level at the end of 21 days of storage. Conclusion: This investigation confirmed that enzymatic cross-linking by TG might be applied effectively to establish 3-D structure of yoghurt and to improve textural properties of the product. Although the best samples with the higher textural properties were produced by using 0. 03% TG, but no significant differences was observed between the mentioned samples and those containing 0. 02% TG. Therefore, TG at the concentration of 2% was found to be the best level of enzyme for the production of yoghurt. Based on our results, effect of addition of TG at 0. 01 % (one unit) on the textural properties of yoghurt was found to be equal to that of addition of more than 1% milk powder.

Background and objectives: Ponyfish (Leiognathus bindus) includes 54. 77% of by-catch in the Mahshahr creeks that has no commercial value due to its small size. So, the production of value-added products, such as protein hydrolysates with high nutritional value could pave the way for full use of this species. By applying enzyme technology for protein recovery in the fish processing, it may be possible to produce a broad spectrum of food ingredients or industrial products for a wide range of applications. Use of proteolytic enzymes is an interesting technique for improving the functional properties of food proteins without losing their nutritional value. The functional properties of fish protein hydrolysate are important, particularly if they are used as ingredients in human food. Among the functional properties of proteins and hydrolyzed proteins, solubility is the most important characteristic that affects other functional properties such as foaming and emulsion formation. Enzymatic hydrolysis of fish proteins generates a mixture of free amino acids and oligopeptides, increases the number of polar groups and the solubility of the hydrolysate, and therefore modifies functional characteristics of the proteins resulted in improving their functional quality and bioavailability. The aim of this study was to evaluate the functional properties of fish protein hydrolysate from Ponyfish. Materials and methods: Ponyfish was hydrolyzed using 1% Alcalase for 1, 2, 3, 4 hours and their functional properties were evaluated. The hydrolysates solubility in pH range of 3-9 and emulsifying and foaming properties in concentrations 2. 5, 5, and 10 mg/ml were studied. Results: The Result indicated that the highest rate of hydrolysis was 28. 06%, which was obtained after 4 h. The Solubility values were above 90% in the pH range 3-9. The solubility of different obtained hydrolysates was increased when pH changed from acidic to the alkaline (P˂ 0. 05). Emulsifying activity index (EAI) and emulsifying stability index (ESI) was decreased by increasing hydrolysis time and protein concentration (P˂ 0. 05). At the same concentration, slight decreases in foam expansion and foam stability were observed when DH of hydrolysate increased (P<0. 05). However, at the same DH, foam expansion and foam stability showed a significant increase by increasing hydrolysate concentration (P<0. 05). Conclusion: The results of the present study showed that the hydrolysates produced from ponyfish can be used as food ingredients or additives to deliver consumer desired characteristic to food products or increasing product shelf life. Also, it is useful as emulsifying and foaming agent in sausages, mayonnaise, salad dressings, beverages, creams, and in a broad pH range.

Background and objectives: Seaweed Colpomenia peregrine is a marine brown macro alga from Scytosiphonaceae family. Secondary metabolites, bioactive compounds along with polysaccharides, are located in the cell wall of these algae. Considering the side effects of utilizing synthetic antioxidants in food industries and the need to search for alternative compounds, performing new studies on antioxidant properties of these compounds is necessary. Therefore, the aim of the current study is to evaluate the antioxidant activity of ethanol extracts from seaweed C. peregrina. Materials and methods: Seaweed was caught from Caspian Sea coastal area and washed with fresh water. Then, samples were dried and pulverized. The ethanol extract of dried seaweed powder was obtained using 80% ethanol for 4h. Then, extract fractionation was employed using hexane, chloroform, ethyl acetate and water as solvents. The antioxidant properties of crude and fractions were tested by determining DPPH and ABTS radical scavenging activity, reducing power, total antioxidant activity and total phenolic content. Results: The extraction yield of ethanol extract from C. peregrina was calculated as 5. 4% (of dried sample). Fractionation of crude extract resulted in four fractions with the highest yield for water fraction (50%) and the lowest yield for ethyl acetate fraction (1%). Evaluation of antioxidant activity revealed that extract fractionation is effectively capable of producing fractions with higher antioxidant properties. Among different fractions, ethyl acetate fraction exhibited the highest activity in DPPH radical scavenging (99. 22%) at 1000 μ g/ mL. The highest ABTS radical scavenging activities were obtained for water (99. 71%) and ethyl acetate (96. 30%) fractions. The activities of hexane, chloroform and water fractions were similar to that of crude extract in ferric reducing assay. However, ethyl acetate fraction showed the highest activity in reducing ferric ion (57. 89%) and total antioxidant assay. The amount of total phenolic content of crude and fractions was calculated between 125 to 278 mg TA/g sample. Conclusion: In general, the results of current study showed that ethanol extract of brown seaweed C. peregrina contained major bioactive compounds suggesting its potential application in food systems as a natural antioxidant.