نشریه فرآوری و نگهداری مواد غذایی
سال دهم شماره 2 (پیاپی 24، پاییز و زمستان 1397)

  Date palm fruit (Phoenix dactylifera L.) is an important agricultural product of Iran. This fruit is a good source of energy and is 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 packaging types during storage period, fruit quality changes and so the product turns sticky and hard due to syrup exudation and moisture loss. To overcome this problem the application of edible coating is proper assistance. Edible coatings have been widely studied in the last years because of evidence about their beneficial effects on fruits and vegetables. Modification of fruits tissue metabolism by affecting respiration rate, extension of storage life, firmness retention, transportation of antimicrobials, antioxidants, and other preservatives and microbial growth control are the main functional advantages attributed to the use of edible films and coatings. There are different kinds of films and coats which are used such as polysaccharide, protein, lipid and composites. Lipid films have good water vapor barrier properties, due to their low polarity. Also temperature is one of the most important factors, which affect the shelf life and the quality of date fruits. The purpose of this research was to study the effect of lipid based edible coating (glycerylmonoestearate and carnauba wax) and storage temperature on quality of Mzafati date fruit. In this research Mazafati date fruit coated with lipid based coatings (glycerylmonoestearate and carnauba wax) and stored at 4 and 25 C° for 3 months. During this period of storage weight loss, hardness, titratable acidity, total soluble solids (brix), reducing sugars, color (lightness, redness and yellowness) and sensory properties (color, texture, flavor and total acceptance) of date palm fruit were evaluated. The experiments were factorial with a completely randomized design. The edible coating, temperature and storage time were the independent variables. Analysis of variance (ANOVA) was conducted for data using SPSS 21 software. Differences among the mean values were also determined using Tukey test. A significant level was defined as a probability of 0.05. Result showed that the coatings were effective to decrease the weight loss and rate changing titrable acidity and color and protecting sensory properties of the date palm. The coated date fruits had more titratable acidity than the control. Although difference of hardness, titrable acidity, total soluble solids and reducing sugars of the coated date palms not significant but carnauba wax coat was more effective to protect color and sensory properties. Edible coating caused increasing lightness, yellowness and sensory scores of date palm significantly. Increasing of storage temperature increased weight loss and decreased yellowness significantly. Increasing of storage time also caused increasing hardness, redness and decreasing lightness and sensory scores. At the end of storage time least value of weight loss and most value of yellowness (8.13% and -0.841 respectively) were related to 4 C° and glycerylmonoestearate coat also most value of lightness and total acceptance score and least value of redness (17.2, 3.1 and 3.99 respectively) were related to carnauba wax coat. 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

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. At first, green pea pod extract was obtained using water, ethanol, acetone and hexane. Total phenolic content (TPC) and antiradical activities of extracts were assessed using colorimetry method, and DPPH and H2O2 radical scavenging activity test, respectively. Then, 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 ºC 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. The highest TPC (140.4 mgGAE/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). 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.

  Organic black grapes, which are produced in Sardasht, West Azerbaijan province of Iran, contain resveratrol and flavonoids and high amount of melatonin having 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 Black grapes were obtained from a vineyard of Sardasht in the West Azerbaijan province of Iran. Nine saturated salt solutions with degree of purity over 98% for generating a range of relative humidity were used and 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 χ2, and the highest R-square. The isosteric heat was determined using the Claussius–Clapeyron equation. At all of temperature levels, moisture sorption isotherm curves of Sardasht black 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 increasing of temperature. According to the evaluation parameters of the models tested, P-value of Darcy-Watt model was consistently less than 10 % and its RMSE and χ2 were lowest, indicating its reliability in predicting moisture sorption behavior of the black grape pulp. The results also showed that, to predict moisture sorption in the grape pulp, BET and GAB models can be used only at high temperatures. The isosteric heat showed a marked increase with decreasing moisture content especially at less than 0.3% (d.b). At the studied range of water activity, the equilibrium moisture content values of the black grape pulp increased with increasing temperature, and the reverse temperature effect wasn’t observed in the range studied of water activities. 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 model was found to be offering the best fits over the entire water activity and temperature range. The isosteric heat decreased with increasing of moisture content by reason of the approaching pulp water properties to the free water one.

  Dry ice cream is a traditional Iranian product which can be reproduced as a new dairy product by using new processing methods and offered as a standard product to the global marketing. In the case of these traditional product has not been investigated and these research is the first scientific study on this product. From similar products of dry ice cream can be noted to khoa, danedar khoa, barfi, pedha, lal peda, brown peda and dulce de leche. The aim of current study was study of the characteristics of quality and shelf life of dry ice cream stored at different temperatures. In this process, dry ice cream was prepared by adding milk, sugar, glucose syrup and shortening then it was packed in conventional cardboard boxes. Then all the samples were kept in three different temperatures (-18, +8 and +28 °C) for 60 days. Next qualitative features of them were investigated by physico-chemical (determine the amount of moisture content, protein, fat, ash, pH, acidity, free fatty acid content, peroxide value), textural (determine the firmness), microbiological (total count and mold and yeast count) and sensory analysis (In terms of color, surface, stiffness, mouth feeling, milky taste, rancidity taste and overall acceptability). The results showed that the amount of moisture, protein, fat and ash of dry ice cream was 14.16 percent, 4.76 percent, 2.48 percent and 1.00 percent, respectively. By passing time and increasing storage temperature, moisture content and pH decreased, but acidity, free fatty acid content, peroxide value, firmness, total count and mold and yeast count increased. In the case of sensory features, by increasing storage temperature and passing time, the related scores of color, surface, stiffness, mouth feeling, milky taste, rancidity taste and overall acceptability were decreased. The dry ice creams that stored at +28 °C were withdrawn from the research from the 13th day because of excessive firmness. The results showed that -18 °C and +28 °C was the most suitable and unsuitable kind of storing temperature regarding to the maintaining of quality and shelf life of dry ice cream, respectively. In addition, -18 °C up to 60 days, +8 °C up to 20 days and +28 °C up to 5 days, showed the best sensory features. According to the results of the research, dry ice cream is viable to be produced in industrial scales and by providing new formulations for this product can be increased the per capita consumption of milk in the country.

Flixweed (Descurainia sophia L.) is an annual plant that found in various parts of the world including Iran. Flixweed seed and its syrup have been traditionally prescribed as a remedy for diarrhea, heatstroke, palpitation, upset stomach, impotence, intestinal inflammation, constipation, skin eruptions, laxative, and antipyretic since ancient times. Despite the unique pharmaceutical and nutritious advantages of this product, its production is faced with two major problems in the food industry; first, its use is not suitable for diabetics because of the high amounts of sugar in the syrup formulation. On the other hand, the sedimentation of flixweed seed syrup is one of the other common problems of this traditional drinking which restrict its commercial production. The aims of this study are the first to investigate the possibility of replacing the sugar with grape syrup as a natural sweetener to producing a functional syrup and secondly the possibility of stabilizing the flixweed syrup using soluble soybean polysaccharide and xanthan gum as natural hydrocolloids. For producing the functional flixweed syrup, the first step was to examine the replacing of grape syrup in various ratios (0:100, 10:90, 80:20, 70:30, 60:40, and 50:50) of sugar in the formulation of syrup as a sugar substitute. Then, in order to stabilize the flixweed syrup, 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, some properties of the syrups (Brix, pH, phase separation, colour, rheological and organoleptic properties) were compared together. Brix and pH were calculated using refractometer and pH meter, respectively. Stability of samples was investigated according to phase separation after thirty days storage of samples 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 syrups were measured by Ultra DV3- LV Rheometer. Organoleptic features of samples containing color, flavor, odor, fluidity, mouth feel, and overall acceptability were evaluated using 10 trained penelists. The experiments were conducted in a completely randomized design and means were compared using Duncan method at p<0. 05. According to the results of this research, the optimal ratio of grape syrup to sugar was 40:60 as substitute of sugar in flixweed syrup. The best functional flixweed syrup included 5% seed, 6% sugar, and 4% grape syrup. Results revealed that the addition of xanthan gum and soluble soybean polysaccharide had no significant effect on pH and Brix of samples. In addition, soluble soybean polysaccharide had no effect on stability of syrups, while the xanthan increased the stability. The use of 0. 3% concentration of xanthan gum completely prevented the phase separation of syrup after thirty days' storage. The most appropriate model for the control syrup and samples containing soluble soybean polysaccharide was Newtonian model, and it was a pseudoplastic model for syrups including xanthan gum. The results of colorometric showed the pasteurization increased the lightness, redness, yellowness, caramelization and browning indices. As well as, the sensory characteristics of stabilized syrups were very similar to blank samples. Based on the findings of this study, that using grape syrup and xanthan gum can be produced the stabilized and functional Flixweed syrup including appreciate organoleptic features

  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. 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 160g sugar, 3g stabilizer-emulsifier, 1 g vanilla powder, and RS or gums; then the dry matter was adjusted 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. 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 had 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 significantly improved by increasing 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. It was concluded that maize RS, Arabic and xanthan gums had the significant impact on physicochemical properties of camel milk ice cream. These ingredients have the potential to be used as stabilizers in ice cream formulations.

  Fruit Juice is beverage that consist of great nutritional value, rich in antioxidants and essential minerals for human health. Maintenance procedures for juices are consist of heat treatment, freezing, cooling and for some juices; clarification and filtration. Clarification is the separation of dispersed and colloid compounds from the system and the maintenance of compounds that are actually solved in the system. In chemical clarification methods (classic) different types of enzymes (pectinase, amylase, protease, etc.) and Auxiliary clarifiers such as gelatin, bentonite, silica gel or a combination of these used. Classic methods are expensive and time-consuming as well as it is difficult to exclusion of these materials. In recent years, membrane filtration has been proposed as a new processing method. The use of membrane filtration is a good way to solve the problems caused by turbidity. The use of membrane processes in the clarification process makes the product more stable qualitatively and, due to the sterile nature of the process, removing of microorganisms is better than conventional methods. In this study, the effect of membrane parameters including pressure (1.2-2.2 bar) and temperature (25-35 ºC) on the viscosity, density and color indices (L *, a *, b *, Total Color Difference, Chroma and Browning index) of sour orange during membrane clarification was investigated. UF membrane process used for clarification of sour orange juice. Physicochemical tests was performed according to Institute of Standard and Industrial Research of Iran (2685). Viscosity was measured Rotational Brookfield viscometer. Image processing method was used for tracing of 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 rheology and color of sour orange. Data analysis and graph drawing was performed using Design-Expert 9.0.0.7 software. Results of the experiments showed that the Browning index, viscosity and density was raised by increasing of temperature, but L* and TCD was decreased in this condition. The Browning index, Chroma and viscosity was decreased by increasing of pressure, but L*, b* and TCD was increased in this condition. Effect of temperature and pressure on a* index is not significant. Linear and quadratic models were the best models to predict of (density, TCD) and (L *, b *, BI and Chroma), respectively. The use of membrane processes, the quality (color) beverages and fruit juices (like orange) is improve. The membrane filtration of sour orange juice without enzymatic pretreatment had a suitable performance in clarification of it.

  Proteins are one of the most important compounds that besides nutritional function for human have a crucial role in food texture development. Proteins are the basic structure of acid-induced gels such as yoghurt. The amount of protein interactions and resulted molecular construction determine the textural and strength of a gel. An effective strategy to improve textural properties of food proteins particularly dairy products is enzymatic treatment with transglutaminase (TG). This enzyme with formation of covalent bonds between milk proteins and trap water in protein network produces a stable and smooth gel with higher water holding capacity. Nowadays, in order to improve the yoghurt texture different methods of milk solids enhancement (increasing the milk solids) like addition of milk powder are used. However, these procedures resulted in higher acidity in the product during storage period. Therefore, with using of TG enzyme as a substituted method, not only the yoghurt texture can be improved, but also the reduction of quality of the product during storage time can be prevented. Set-type yoghurt samples were manufactured from cow's milk treated with different concentration 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 percent). Yoghurt sample that did not contain any TG was regarded as 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 showed that all variables had significant effects (p<0.05) on studied parameters. In general, except color and taste, other sensory scores usually were affected by the variables, i.e. milk powder addition, transglutaminase treatment and storage period. By increasing the variables levels, particularly increase of enzyme concentration, the appearance and texture of yoghurts were improved. Results also showed that by increasing enzyme concentration and milk solids, the amount of hardness, consistency, adhesiveness and viscosity index were meaningfully increased. In all the yoghurt samples, the hardness and consistency reached to maximum level at the end of 3 weeks’ storage period. This investigation confirmed that enzymatic cross-linking by transglutaminase might be applied effectively to establish three dimensional structure of yoghurt and to improve texture properties of the product. Although the best samples with the higher textural properties were produced with using 0.03 percent of TG enzyme, but no significant differences with samples containing 0.02 and 0.03 percent was observed. Therefore, for set yoghurt production utilization of 0.02 percent TG enzyme was determined as the best level of TG treatment. Based on our results, effect of addition of 0.01 percent enzyme (one unit) on the textural properties of yoghurt was equal to addition of more than one percent milk solids (milk powder)

  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 nutritional value could pave the way for full use of this species. By applying enzyme technology for protein recovery in 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 lossing 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 hydrolysed proteins, solubility is the most important characteristic which effects other functional properties such as emulsion and foam 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, improving their functional quality and bioavailability. The aim of this study was to evaluate the functional properties of fish protein hydrolysate from ponyfish. Ponyfish was hydrolysed using 1% Alcalase during 1, 2, 3, 4 hours. and their evaluated functional properties Were evaluated. The protein hydrolysate solubility in the pH range of 3-9 and emulsifying and foaming properties in concentrations 2.5, 5, 10 mg/ml were studied. Result indicated that the highest rate of hydrolysis was 28.06%, which obtained after 4 hour. The Solubility value were above 90% in the pH range 3-9. The solubility increased at all hydrolysis times by changing the pH of acidic to the alkaline (p˂0.05). Emulsifying activity index (EAI) and emulsifying stability index (ESI) decreased by increasing hydrolysis time and protein concentration (p˂0.05). At the constsnt concentration of hydrolysate used, 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 of hydrolysate showed a significant increase by increasing concentration (p<0.05). Results in the present study showed that hydrolysates produced from ponyfish can be used as food ingredients or additives to impart a increase consumer desire characteristic to food products or increase food storage time. Also use it is useful as emulsifying, foaming agents, in sausages, mayonnaise, salad dressings, beverages, creams, etc., all these in a broad pH range

  Seaweed Colpomenia peregrine is a marine brown macro alga from Scytosiphonaceae family. Secondary metabolites are one of bioactive compounds which, along with polysaccharides, are located in the cell wall these algae. In the process of polysaccharide extraction, secondary metabolites are primarily removed and discarded in depigmentation step. While, this extract possesses precious bioactive compounds such as polyphenols, peptides, pigments, etc. Considering the side effects of utilizing synthetic antioxidants in food industries and the need to search for alternative compounds, executing new studies on antioxidant properties of these compounds is necessary. Therefore, the aim of current study is to evaluate the antioxidant properties of ethanol extract from seaweed C. peregrina. Seaweed C. peregrina was caught from Caspian Sea coastal area and washed with fresh water. Then, samples were dried at 60 °C and pulverized. The ethanol extract of dried seaweed powder was obtained using 80% ethanol at 60 °C for 2h. Then, solvent partitioning was respectively employed using hexane, chloroform, ethyl acetate and water as solvents. The antioxidant properties of crude and fractions were tested using DPPH radical scavenging activity, ABTS radical scavenging activity, reducing power, total antioxidant activity and total phenolic amount. The correlation between total phenolic content and antioxidant activity was also analyzed. The extraction yield of ethanol extract from C. peregrina was calculated as 5.4% of dried sample. Solvent partitioning of crude extract resulted in four fractions with the highest yield for water fraction (50%) and the lowest yield for ethyl acetate fraction (1%). The evaluation of antioxidant activity has revealed that the solvent partitioning is effectively capable of producing fractions with higher antioxidant properties. Among different fractions, ethyl acetate fraction exhibited the highest capability in DPPH radical scavenging (99.22%) at 1000 μg/ mL. The highest ABTS radical scavenging obtained for water (99.71%) and ethyl acetate (96.30%) fractions, respectively. Hexane, chloroform and water fractions exerted a similar ability with crude extract in reducing ferric ions. Conversely, ethyl acetate fraction showed the highest activity in reducing ferric ions (57.89%) and total antioxidant activity. The amount of total phenolic content of crude and fractions was measured between 125 to 278 mg TA/ g sample which indicated poor correlation with antioxidant activity. Results of current study revealed that secondary metabolites of ethanol extract from seaweed C. peregrina possess a notable antioxidant activity. Hence, after further studies, ethyl acetate fraction compounds could be introduced as a natural antioxidant in food systems