مجله علوم و صنایع غذایی ایران
سال هشتم شماره 2 (پیاپی 30، تابستان 1390)

The changes on proximate and fatty acids profile during surimi production and also during frying of fish fingers produced from mince and surimi of common carp were investigated. In surimi production process, moisture increased from 70.95% to 75.17% and instead crude protein and fat was reduced from 18.71% to 12.22% and 2.27% to 1.98%, respectively. After frying of fish finger produced from mince and surimi in sunflower oil, crude fat were increased from 2.27% to 5.58% and 1.98% to 4.01%, respectively. Crude protein and moisture was decreased during frying. Totally, sixteen fatty acids were identified of saturated, polyunsaturated and monounsaturated fatty acids in fish fingers. Washing of fish mince reduced myristic acid content from 7.98% to 1.30%. During frying the content of oleic, linoleic and palmitic acid were increased in fish fingers and instead the other fatty acids percent was decreased after frying. PUFA/SFA ratio in fish finger produced from mince and surimi during frying was increased from 0.45 to 0.65 g/100 g fatty acid and 0.61 to 0.62 g/100 g fatty acid, respectively.

Lycopene is a naturally red carotenoid that can be produced by some plants and microorganisms. It is not provitamin A, but it has 11 conjugated double bounds with high antioxidant activity. The antioxidant activity of lycopene has been extensively evaluated based on its ability to scavenge free radicals. Lycopene is a major carotenoids found in human serum and by virtue of its ability to interact with free radicals can preserve the important cell biomolecules such as DNA, proteins and lipids and it plays a significant role in the prevention of chronic diseases such as cardiovascular, prostate, osteoporosis and gastrointestinal. Tomato and tomato products are the most important sources of lycopene and the increasing consumption of lycopene diets is benefit to human health. Because of high demand for natural carotenoids, the production of kinds of carotenoids from microbial sources has been focused by many researchers. Lycopene has been found in several microorganisms. The production of lycopene could been enhanced by using kinds of media cultures, metabolic stimulators and inhibitors, mutagenic materials, environmental and cultural factors and genetic engineering. This review summarized the information about structure and characteristics of lycopene and it,s role in human health and introduce the some microbial resources of it.

A total of 100 samples were collected from 5 kinds of Caned fish from retail shops to test for content of Lead, Copper, Tin and Cadmium residues. All the samples were prepared by the method recommended by (A.O.A.C) and were checked by Potentiometric Stripping Analysis Method (P.S.A). Data were compared with the permitted level of each metal by using one sample T test, also the ANOVA test was used to compare the amount of each metal among the samples. The results showed that mean value of Lead, Copper, Tin & Cadmium residues in the samples were 99.6 ppb, 2.087 ppm, 2.578 ppm and 0.031 ppm respectively. The mean value of residues of Lead, Cadmium, Tin and copper in fish cans were in the standard range but 28.4% of the samples contain Lead and 2% contain Cadmium more than standard limit. The amount of Copper, Tin residues were in the standard range. There was the significant difference in the Copper and Cadmium residues among the different kind of cans (P<0.05) but there was no significant difference in Lead and Tin residues among the different kind of cans (P>0.05).  Regarding to the results of this study some of the fish can producing in Iran containing Cupper, Tin and Lead residue more than standard limit of these metals in this product. Therefore it is recommended to conduct the other study to confirm the source of these metals in fish cans.

The changes of mineral elements of the Abbot, Alison, Bruno, Monty and Hayward cultivars of kiwifruit (Actinidia deliciosa CV) were obtained from The Iran Research Center of Citrus (Tonekabon, North part of Iran) and were measured by ICP (Inductively Coupled Plasma) in the cold storage (at T= 0-4 0C, RH=75-85%) during 0, 9 and 18 weeks. Content of mineral elements (after harvesting) were in the ranges: Ca (42.726- 79.590), K (279.890-372.271), Mg (18.977-32.799), Na (1.444-2.5), Fe (0.290-0.521), P (31.296-42.221), Cu (0.037-0.207), Zn (0.162-0.308) and Mn (0.042-0.062 mg/100g fw). Statistical analysis showed that, potassium was the main mineral elements in the all studied cultivars and the Alison cultivar had the highest contents of mineral elements. In all cultivars of kiwi fruit the contents of mineral elements was significantly change during cold storage (P<0.01).

The aim of this work was to study the effect of adding gellan gum and glycerol to film-forming solution on physical and mechanical properties of whey protein/gellan gum emulsion films and to produce edible coatings from whey and gellan gum and determine its effect on storage life of apricot. Whey protein coatings were prepared by dispersing 10% protein in distilled water; and plasticized with glycerol(Gly). Also gellan gum was added at different levels(0, 0/2, 0/4 and 0/6gr).

Therefore apricots were dipped in this coatings solution for 1 minute at 20˚C and air dried. Coated fruits together with the uncoated fruits(control) were placed in open dishes and stored at 4˚C and 85% RH for 1 months. Weight loss, total soluble solid(TSS), titrable acidity, pH, skin color, flesh firmness and overall acceptability of coated apricots and control were measured weekly. 

The result revealed that the weight loss and changes in the quality parameters were much lower in coated apricots as compared with those. Color changes were also studied using a Hunter lab colorimeter. Finally results showed that the applications of whey coating increased overall acceptability, quality and storage life of apricot, while decreased its weight loss during storage.

The emulsion films were evaluated for physical and mechanical properties. Increasing the level of gellan gum in the films led to increase in Modulus(EM) and Tensile Strength(TS) but increasing gum to 0/6gr made less increase in Modulus(EM) and Tensile Strength(TS). About Elongation(EL), was observed increase too but in films that produced with 0/4gr gum, there was a slight decrease.

Determination of physical and mechanical properties of agricultural products is the basis for designing or modification of processing equipments. Accordingly, in this research, some of physical and mechanical properties of two varieties of almond were investigated. The mean values of geometrical properties including; length, width, thickness, the geometric mean diameter, mass, volume, surface area and sphericity for Azar variety were 32.42, 21.74, 14.76, 21.80 mm, 4.157 gr, 2793 mm3, 1509 mm2 and 67.49% and for Nonpareil were 29.71, 19.12, 12.99, 19.22 mm, 1.305 gr, 2442 mm3, 1168mm2 and 63.80%, respectively. Also, properties such as ; true density and bulk density, frictional properties of Almond on the plain steel, galvanized steel and aluminum for the two varieties of Almond, that is, Azar and Nonpareil were measured. At the present research, also the mechanical properties such as maximum force, energy and power requirement to rupture of Almond nut, measured and assessed under compression loading between two parallel plates. The tests were carried out in three levels of size (small, medium and large), three loading speeds (10, 100 and 200 mm/min) and three loading axes (X, Y and Z) with 10 replications. The effect of three factors; size, speed, direction of loading and their interactions were measured for both varieties. Finally, the mean values of physical and mechanical properties both varieties were compared. The mean values of force, energy and power requirement to rupture of nut for Azar variety were 884.6 N, 447.3mJ, 0.681W and for Nonpareil were 56.2 N, 31.4 mJ, 0.045 W, respectively. The results showed that the mean values of mechanical properties of Azar variety were considerably more than that of Nonpareil variety. Also, it was revealed that the effect of size, speed and loading direction on mechanical properties was significant in both varieties.

Scanning Electron microscopy (SEM) has been used for the study of Longissimus Dorsi muscle of lamb. Three treatments including raw (control), conventional heating and microwave heating were used for the samples with the temperatures of 163 C and domestic microwave was applied with the frequency of 2450 MHz and 700 wattages level. In all images were taken for conventional  heating no surface damage was observed. More structural damages were observed in microwave heating  at 700 watages levels. Distribution in microwave heating causes surface damage to muscle fibres and separation of some parts of muscle fibres was also clear.

Bread is the most consumed food of human. Amongst different types of breads, white breads are   of great favorite, however these kinds of breads contain low amount of dietary fiber compared to dark breads. On the other hand, the positive effects of fibers on human health have been well documented. In order to increase the fiber content of the bread, it is possible to use different fiber sources other than the bran in order to keep the favorable appearance of the bread. In this research the effects of addition of two fiber sources: cross-linked wheat starch and short barns at three levels of zero, 5 and 10 % on the quality of dough and flat bread (Barbari) were studied. The results showed that addition of 5% of cross-linked wheat starch had the best effects on dough and bread quality. In many aspects both fibers used, had similar effects, while in the case of color, cross-linked wheat starch (opposite to bran) did not change the color of the bread. Therefore it is possible to use cross-linked wheat starch to increase the dietary fiber content of the bread without any undesirable effects on bread quality.

In this study, physicochemical properties, sensory characteristics and shelf life of muffin prepared by substitution of egg white with different levels of whey protein concentrate (WPC) were evaluated.

WPC at three levels – 25, 50 and 75 %– was considered as variable treatment. Physicochemical properties including butter pH, butter consistency, cake pH, weight loss, density, moisture, shelf life properties including water activity () and hardness after 1, 2 and 10 days storage and sensory properties including crust color, taste, texture and total acceptance were measured and the result were analyzed. Data analysis showed that WPC substitution levels affected all of properties.  In comparison with control butter pH, cake pH, moisture, density,   and hardness after 1, 2 and 10 days storage decreased whereas consistency and weight loss increased with increase of substitution level. Also WPC substitution levels affected all of sensory properties. Color score increased with 25 and 50 % WPC but decreased with 75% WPC. Texture, taste and total acceptance scores decreased with increase of substitution. No significant difference of taste and total acceptance scores with control up to 50 % replacement level was noticed; however it became significant at 75% replacement level.

Kombucha is a non-dairy fermented beverage. Traditional substrate for kombucha production is sweetened black tea. Kombucha culture can also use other carbohydrates such as inulin and oligofructose as a substrate. In this study inulin and oligofructose extracted from Jerusalem artichoke tuber at 0, 2, 4, 6, 8 and 10% were used as substrates for kombucha fermentation. The chemical changes during fermentation period were compared with those occurred during traditional substrate fermentation at the same concentrations. The rate of inulin fermentation by kombucha culture was higher than that of sucrose fermentation. The pH value in kombucha produced with inulin was higher than that of traditional product. Acetic acid and lactic acid measurements using HPLC showed that the acetic and lactic acid contents of traditional product was higher and lower than the kombucha produced with inulin, respectively. Soluble protein content and antioxidant activity was higher in kombucha produced with inulin as a substrate. Thus, using inulin as a substrate for kombucha culture decreases fermentation time and produces a product with high pH.

In this study the combined effect of ultrasound and heat on inactivation of pectin methylesterase (PME) in fresh orange juice was investigated. To this end fresh orange juice was sonicated at 50, 60, 70 and 80 °C for 10, 15, 20, 25, and 30 minutes at various acoustic amplitudes and constant frequency of 30 kHz and the residual activity of PME was then measured. The results showed that ultrasound had a synergistic effect on heat resulting in an increase in the inactivation of PME. However, calculation of kinetic parameters and reaction constants indicated that increasing temperature decreased cavitation intensity and hence contribution of ultrasonic waves to PME inactivation. On the other hand, the acoustic amplitude level was found to initially increase and then diminish the rate of enzyme inactivation. In this article these changes are explained by activation parameters of DS# and DH#  and possible mechanisms for ultrasonic inactivation of PME are discussed.

Chocolate is a popular product for cunsumers in different ages . Chocolate sweetness  is related to the sucrose in its formula , it can be replaced by sweeteners like low digestible carbohydrates (LDCS) .The results would be reduction in calories and glycemic index and prevention of tooth decay. The aim of this study was to replace  the sucrose with the inulin (as dietary fiber) and tagatose (as natural keto hexose  with sweetness similar to sucrose). The ratio of the replacements were 100:0 , 75:25 , 50:50 , 25:75 and 0:100 inulin:tagatose in milk chocolate formula and the chemical and rheological properties of samples were tested. Results indicated that when the amount of inulin reduced and amount of tagatose  increased in chocolate formula, moisture contents reduced but aw values increased . The hardness of samples was related to the percentage of tagatose when tagatose added  to the formula, hardness was increased and the hardness of sample with 100% tagatose and control were comparable. In color parameters the least amounts of l* ,a*,b*,c* and hue° were observed in chocolate with 100% inulin which they went up when amount of tagatose was increased in formula. When inulin reduced in samples,  and  incresed and the lowest real and linear yield stress occurred in the sample with 100% inulin. By reduction of inulin, apparent and plastic viscosity were reduced. The least amount of apparent and plastic viscosity was observed in sample with 25%inulin-75% tagatose and the viscosity in formula with tagatose had no significant difference with control. Flow property index also reduced with reduction of inulin. Results showed that the samples with 50% inuin -50% tagatose and 25% inuin -75% tagatose  and 100% tagatose were the best ratio of the sugars as replacement of sucrose in formula, the two formers formulas are the best formula from nutrition point of view and are considered  as a functional food.

In this research, antimicrobial activity of extract of Salvia leriifolia were investigated with different concentrations of the extract (5000, 10000, 15000 and 20000 mg/kg) on Staphylococcus aureus count and Total viable count in hamburger at different time intervals: after treatment (day 0) and after storage for 15, 30 and 45 day at -12˚C, all microbiological analyses performed at 3 replication. The results showed that both of microbial total count and the number of Staphylococcus aureus in all samples with different concentrations of extract, decreased during storage. This decreasing effect was significant on day 15 and 30 for Staphylococcus aureus and total count, respectively. Our data also showed that the extract of Salvia leriifolia at highest concentration (20000 mg/kg) caused maximum reduction compared to other concentrations and extract at lowest concentration (5000 mg/kg) was less effective in initial Staphylococcus aureus population and microbial total count. These data indicate that Salvia leriifolia extract can exhibit antimicrobial activity against Staphylococcus aureus; so it can be considered as an alternative natural preservative in food products.