Food Technology
Azade Farazmand; Hossein Jalali; Ali Najafi
Abstract
Introduction Potato strips are one of the most widely consumed products, and due to their high oil content, they have caused public health concerns. Therefore, efforts to reduce oil absorption can alleviate these concerns to some extent. Edible coating is an effective way to reduce oil uptake, because ...
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Introduction Potato strips are one of the most widely consumed products, and due to their high oil content, they have caused public health concerns. Therefore, efforts to reduce oil absorption can alleviate these concerns to some extent. Edible coating is an effective way to reduce oil uptake, because the oil absorption is a surface phenomenon. Edible coatings should adhere well to the surface of the product and provide a uniform and complete coverage for the product. Preventing the migration of oxygen, carbon dioxide, aromas, oils, moisture, improving the appearance of food and mechanical properties. In this study, the possibility of reducing oil absorption in French fries was investigated using okra mucilage and chitosan as edible coatings. Material and Methods The okra was washed and then cut into about 1 cm pieces and poured into containers with lids. Then water in a ratio of 2:1 weight of okra was added to the container and completely covered its surface. The okra were refrigerated for 72 hours until the mucilage was completely extracted. Then the mucilage was smoothed. This solution was considered as 100% mucilage solution. To prepare a 50% solution of okra mucilage, 100% solution was mixed with an equal amount of distilled water and filtered. To produce a solution of 0.75 and 1.5% of chitosan, 7.5 and 15 g of chitosan powder was dissolved in 1000 ml of 1% acetic acid and then adjusted to pH 5. Then 5 g of glycerol was added as a plasticizer. The potato slices were first blanched in 0.5% calcium chloride solution at 90°C for 5 minutes. Then, they were immersed in coating solutions at 60°C for 5 minutes. After coating, the potato strips were fried at 180°C using a fryer and then various characteristics including coating percentage, oil absorption, and moisture content, texture firmness, peroxide value, acid number, color indices and sensory properties were examined. Design Expert 8.0.7.1 software was used to analyze the results and to draw the curves. Results and Discission The results showed that the increasing the amount of chitosan led to better coating formation in comparison with okra. The highest coverage was observed in the concentration of 1.2% chitosan and 0% okra mucilage (2.38%) and the lowest was observed in the control sample (0.11%). It was also observed that with increasing the concentration of chitosan and okra mucilage, the amount of oil absorption decreases. However, the amount of oil absorption in high concentrations of okra mucilage increased slightly. The highest oil uptake in the control sample was 20% and the lowest was observed in the sample of fried strips covered with 41% okra mucilage and 1.5% chitosan at 15.44%. The obtained model of oxidation index was not significant. The effect of okra mucilage and chitosan concentration on the texture of the samples (p <0.05) and the color indices of a* (p<0.01) and L* (p <0.05) were significant. For sensory attributes, the highest and the lowest taste score was observed for samples coated with 100% okra mucilage and 0.75% chitosan and samples coated with 18% okra mucilage and 0% chitosan respectively. Conclusion The aim of this project was to reduce the oil absorption of fried potato strips by coating them with chitosan and okra mucilage. Optimization to minimize the consumption of okra and chitosan mucilage showed that coating with 74% okra and 0.89% chitosan is suitable for coating potato slices. The desirability of this optimization was 71%, which is a reasonable percentage.
Food Engineering
Hassan Sabbaghi
Abstract
Introduction: Doughnuts are fried foods that absorb significant amounts of oil, and commercial doughnuts made from wheat flour typically contain 24 to 26 percent oil. The use of additives, especially hydrocolloid compounds, in reducing the oil uptake in doughnuts is a practical method because there is ...
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Introduction: Doughnuts are fried foods that absorb significant amounts of oil, and commercial doughnuts made from wheat flour typically contain 24 to 26 percent oil. The use of additives, especially hydrocolloid compounds, in reducing the oil uptake in doughnuts is a practical method because there is no need to make changes in the industrial design of the equipment. Usually, the level of these compounds used to achieve the desired properties in food systems is less than 2% dry basis. When these compounds are added to the dough, they form a gel as soon as possible, which has a high water holding capacity in contact with hot oil, and this will be effective in maintaining and controlling the moisture content of the product and preventing oil penetration. Controlling moisture outflow from the product reduces the rate of moisture migration and compounds from the food into the frying oil, and subsequent peroxidation reactions in the oil consumed are reduced, thus increasing the useful life of the oil. Therefore, in this study, the effect of xanthan gum and carboxymethylcellulose on doughnut quality characteristics was studied. Materials and Methods: For this purpose, in the formulation of doughnut dough, xanthan gums, carboxymethylcellulose and a combination of these two gums (50:50) were used at the rate of 0.5, 1 and 1.5 percent based on the weight of the dry matter of the dough. The doughnut dough was prepared and molded. The fermentation was carried out for 30 minutes under similar industrial conditions (40°C and 40% humidity). Then the frying process at 180°C, icing and packaging were performed, respectively. The moisture content of the dough and doughnuts, the oil uptake of doughnut, density, color and the porosity ratio of the samples were measured. Also, the qualitative characteristics of shelf life, including soft tissue assessment, non-absorption of icing and non-growth of mold were investigated within 14 days. Statistical analysis was performed in a completely randomized design (p<0.05). Results and Discussion: The results showed that, the moisture content of the samples always increased with elevating the percentage of hydrocolloid compounds. Oil absorption decreased with increasing gum percentage and the lowest oil content was observed in the samples containing xanthan gum. Unlike xanthan, the density decreased and the volume increased with elevating the percentage of carboxymethylcellulose gum. Therefore, the highest porosity and softness of the tissue were found in samples containing carboxymethylcellulose. The brightness parameter (L*) was higher in samples containing xanthan, which could be due to the higher moisture content. The red parameter (a*) was also higher in the samples containing xanthan, which due to the higher compression of the product, a relatively more red pigment was observed with increasing xanthan level. The yellowness parameter (b*) in xanthan-containing samples was lower due to reduced oil absorption. The intensity of the color changes (dE) decreased as the percentage of gums increased. Non-absorption of icing was less in hard sample containing xanthan, which could be due to xanthan's competition with gluten in suction of surface water. Mold growth was not observed for any treatment. Overall, the best additive ratio of xanthan gum was 0.5% in terms of reduced oil absorption. Also, the use of carboxymethylcellulose at the level of 0.5% alone could improve the softening of the product texture and made the doughnut with larger volume. Simultaneous use of xanthan gum and carboxymethylcellulose showed behavior under effect of xanthan gum.In general, xanthan gum was more effective than carboxymethylcellulose gum in reducing oil uptake and moisture retention at test levels. Xanthan has shown the greatest reduction in oil absorption due to its thermal gelling and thickening properties, as it has a high capacity for water retention when product is in contact with hot oil. Since the xanthan gum is inexpensive, its effects on product volume can be further investigated in research work, along with bulking agents or other hydrocolloid compounds.
Najimeh Taghavi; Aman Mohammad Ziaiifar; Habibollah Mirzaee; Alireza Sadeghi Mahoonak; Mohammad Ghorbani; Hassan Sabbaghi
Abstract
Introduction: Frying is a unit operation in which food is heated in oil to alter its eating quality. First reviews of frying performed on the principles of heat and mass transfer and oil uptake in foods, because during the frying process heat and mass transfer occurred between product and frying medium. ...
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Introduction: Frying is a unit operation in which food is heated in oil to alter its eating quality. First reviews of frying performed on the principles of heat and mass transfer and oil uptake in foods, because during the frying process heat and mass transfer occurred between product and frying medium. In fact, the food loses moisture content and lost water will replace with oil. The moisture loss in the product causes rapid formation of the crust while the core remains soft and moist; therefore higher oil uptake occurred in the crust. There is an argument about the effect of frying on the sensory characteristics of foods, changes of nutritional value and health concerns in fried foods and methods applied to reduce oil content. Consumers prefer eating foods with lower oil content. One of the typical methods for reducing oil uptake in food commodities is using of coating before frying process. Edible coatings are known as a thin layer of edible polymers which is placed on the surface of the food. Application of edible coating decreases some destructive factors like the presence of various gases such as oxygen and carbon dioxide and humidity. Hydrocolloides are referred to a group of polysaccharides and proteins which create many features such as consistency in aqueous solutions, foams stability, emulsions, improve the sense of mouth and create a similar state of fatty and oily mode for products with lower content. In fact hydrocolloid coatings can reduce the excessive oil uptake due to their interesting thermogelling properties and at the same time they are invisible and have no negative influence on the sensory attributes of fried foodstuff. Even more, fried products have low fat content with improved nutritional values, higher crispiness and better palatability. Pishmeh is described as deep-fried dough pastry which is usually prepared by local producers of Turkmen (Iran). This product absorbed high oil content during frying process. This study was carried out to evaluate the effects of hydrocolloid coatings including Aloe Vera, Carboxymethyl cellulose (CMC) and Xanthan on the oil uptake of Pishmeh.
Materials and methods: Hydrocholloid materials such as Aloe Vera, Carboxymethyl cellulose (CMC), Xanthan and complex of Xanthan-CMC were used. The gums were prepared at concentrations of 0.5 and 1% by dissolving in water at 70 ° C by stirring with a homogeneous mixer until a clear suspension was obtained. To extract the Aloe Vera gel, first, a thick epidermis (The shell) was separated from parenchyma using cutter. The parenchyma was immersed in a container of distilled water to lose bitter taste for 5 minand then parenchyma was taken out from water and transferred into a mixer (for 1 minute at 25 °C) and finally converted to a uniform colloidal solution. In the next step, the prepared dough samples were immersed in the colloidal suspensions for 1 min and the coated samples were placed on a mesh tray to remove the excess residuary coats. The samples were fried in sunflower oil at 170 °C for 6 min. The samples were then placed on a metal tray after frying to remove excess oil. After removing the oil and reaching the ambient temperature, physical and chemical tests were carried out on the sweet Pishmeh. The experiments included determination of moisture, fat content, measurement of coating parameters (such as coating ratio and frying efficiency) and color analysis.
Results and Discussion: The result showed that coating by hydrocholloid materials was led to decrease water loss in comparison to non-coated sample (control) during frying. Furthermore, oil uptake of coated samples was lower than control sample (p
Battol Attar; Seyedeh Zahra Seyed Alangi; Sara Jorjani
Abstract
Introduction: Value-added products, referring to the fact that a raw commodity or commodities are transformed into a processed product through use of materials and technology, may have different appearances, textures, tastes and smells than their raw material. Fried product is one of the most popular ...
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Introduction: Value-added products, referring to the fact that a raw commodity or commodities are transformed into a processed product through use of materials and technology, may have different appearances, textures, tastes and smells than their raw material. Fried product is one of the most popular ready to eat foods all around the world. They have excellent sensory qualities due to their appealing flavor and texture. Products such as shrimp usually coated with breading before frying to induce additional sensory and quality attributes. The process of battering and breading provides special functions in food products, including improved appearance of the products, increased texture crispness, reduced oil uptake during the frying process and increased the shelf life of the coated products.
Hydrocolloids are used extensively in food technology as thickening and gelling agents, stabilizers, and emulsifiers. In addition, the hydrocolloid coatings are of great interests due to their desirable barrier properties to gas/moisture and good mechanical characteristics. Thus, a variety of foods have been coated with hydrocolloids to prevent moisture loss, preserve texture, and maintain color, consequently extending the product shelf-life. Specifically, the hydrocolloid coatings are often known to reduce the oil uptake of fried foods. The mechanisms of the oil uptake during frying are associated with heat transfer from the frying oil to the food and the migration of water and oil. Various hydrocolloids have been tested as an oil barrier coating material and the effectiveness of hydrophilic and thermo-gelling hydrocolloids in reducing oil uptake during frying has been well reported in previous studies.
Material and Methods: Fresh peeled shrimp (Litopenaeus vannamei) was purchased from Gomishan city, Golestan province, Iran. Xanthan gum was bought from Asia Research Petrochemisry (Iran). White flour, corn flour, breading powder, oil and salt were prepared from the local supermarket. All other chemicals used in this study had analytical grade and were gained from Fluka or Merck companies.
The freezed shrimps were thawed at room temperature before processing. Four different formulations were applied in pre-dusting and battering as following:
Control= without xanthan in pre-dust and batter,
A=2% xanthan in predust,
B=2% xanthan in batter,
C=1% xanthan in predust + 1% xanthan in batter.
The batter formulation was consisted of wheat flour (75%), corn flour (24.5%), salt (0.5%). The dry ingredients were blended for 3 min at speed 2 m/s in a Kenwood Major Classic mixer (Kenwood-BL460) with water (1:1.4 solid to water ratio). In each treatment, firstly, pre-dusting was done and then, battering. Afterwards, it was allowed to drip additional batter for 30 s. For final coating, orange bread crumbs were used (Gols Company). The samples were pre-deep-fried by sunflower oil at 190 °C for 30 s (Fritaurus Professional 3 domestic fryer, Barcelona, Spain). The treatments were cooled to room temperature for 30 min. Then, they were placed in plastic freezer bags (LDPE film, thickness 150 μ) and stored at -18 °C.
Moisture content in the samples was determined in quadruplicate according to the Association of Official Analytical Chemists (AOAC) (2000) method. Fat content of fried products was distinguished using Soxhlet extractions according to the AOAC (2000) method No. 992.15.
Batter pickups (%) were determined as following equation:
Batter pickup (%) = (Weight of coated shrimp–Weight of uncoated shrimp)/(Weight of coated shrimp)×100
Product yield (%) was calculated by weight of the cooked shrimp block/ weight of the raw shrimp block × 100.
Quantitation of fatty acid methyl esters in raw and fried breaded shrimp was carried out by gas chromatography (Unicam-4600) with 30 mm×0.25 mm column (Film Tekness-0.22 μl) and FID detector, using glyceryl tritridecanoate (C13:0) as an internal standard (Sigma, Barcelona, Spain). Fatty acids were expressed as percentage of total fatty acid methyl esters or in absolute content (mg/100 g food).
Fried shrimp coated with the selected formulations was evaluated by a trained sensory panel of 12 members. Each sample was randomly numbered and presented to the panel member. A hedonic panel was also performed by the same panelists, who evaluated aroma, taste, texture, color, appearance and overall acceptability characteristics. A hedonic 5-point scale was used, 1s unusable, 2s dislike, 3s acceptable, 4s like and 5s like very much. All data are reported as mean± standard deviations of triplicate. One-way analysis of variance (ANOVA) was used to compare the means of all evaluated parameters. Differences were considered significant at P
Reza Farhoosh; Seyed Mohammad Ali Razavi
Abstract
Introduction: In this research, the effects of coating by Basil seed gum (BSG) (0.5 and 1%, w/w) compared to that by common gums such as xanthan and methylcellulose (MC) on the oil uptake, moisture removal, color, and texture in deep-fat fried potato strips were investigated. Today, numerous processed ...
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Introduction: In this research, the effects of coating by Basil seed gum (BSG) (0.5 and 1%, w/w) compared to that by common gums such as xanthan and methylcellulose (MC) on the oil uptake, moisture removal, color, and texture in deep-fat fried potato strips were investigated. Today, numerous processed foods are prepared by deep-fat frying all over the world, since in addition to cooking, frying provides unique flavours and textures that improve the overall palatability. In fact, the desirable characteristics of most fried foods are derived from the formation of a composite structure: a crispy, porous, and oily outer layer or crust, and a moist cooked interior or core, whose microstructures have been formed during the process. In addition, the high oil content is costly to the processor and results in an oily and tasteless product . Also, Excess consumption of fat is considered as the key dietary contributor to coronary heart disease and perhaps cancer of the breast, colon, and prostate . The concern to develop healthier products that contain less fat, absorbed during industrial pre-frying and frying processes, is one of the prevailing factors in the latest research trends in this area, prompting studies of ways to lower the oil content of fried food. An edible coating (EC) is a thin layer of edible material formed as a coating on a food product, the EC are applied in liquid form on the food, usually by immersing the product in a solution generating substance formed by the structural matrix (carbohydrate, protein, lipid or multicomponent mixture), When frying coated food pieces, the film hinders absorption of the oil, improving its nutritional qualities and reducing the fat content and calories of the final product. Basil (Ocimum basilicum L.) is one of the domestic plants in Iran that is produced and used as a pharmaceutical plant in high quantity. When the seed of the O. basilicum L. is soaked in water, the outer pericarp swells into a gelatinous mass due to the presence of a polysaccharide layer. the present study aimed to expands the scope of previous works and focus on the effect of basil seed gum (as a novel hydrocolloid) on oil uptake and product quality (texture and color) during deep-fat frying of potato strips. In the first part of the study, investigate and compare the effects of endemic hydrocolloid, basil seed gum with xanthan(xan) gum and methyl cellulose(MC) for use as commercial hydrocolloids for coating edible.Materials and methods: Aqueous suspensions of 0.5 and 1% (w/w) were provided and used for coating formulations. blanched samples of potato were dipped in the coating suspensions for 2 min and rinsed to removal excessive gum then dipped samples dryed in oven 150 ºC for 3 minute. Frying was carried out in a controlled temperature deep fat fryer (Moulinex, Toucan Automatic). For each stage, nine samples were fried in 3 L of blended oil of canola: palm olein: olive oil (75:15:10, respectively). The uncoated and coated potato strips were fried 6 min at three temperatures (160 °C, 180 °C, and 190 °C).Rheological characterization of gum dispersions were measured using a rotational viscometer (Bohlin Model Visco 88; Bohlin Instruments, Worcestershire, UK) equipped with a heating circulator (Julabo, Model F12-MC; Julabo Labortechnik, GmbH D-77960, Seelbach, Germany). According to the viscosity of dispersions, appropriate measuring spindles (C25 and C30) were selected during viscosity measurements. Moisture and fat contents were determined according to the method of AOAC (1996). The color Color of crust models was measured using an image processing technique . Crispiness of potato strips was evaluated in term of hardness by a penetration test performed in a Texture Analyser (QTS25 CNS Farnell, UK). The Conical prob diameter and the cross-head speed was 3 mm and 60 mm/min, respectively. Statistical analysis was performed using factor completely randomized design in Mstat version 1.42 software. The level of statistical significance was determined at 95%. If significant difference was found, the treatments were compared by using Duncan’s multiple comparison test.Results and discussion: Solutions of BSG and XAN exhibited interesting pseudoplastic behavior with the viscosity decreasing with increasing shear rate( from 10 – 1001/s). No Newtonian region was detected at low shear rates suggesting that the zero-shear viscosity could exist at very low shear rates. The presence of high yield stress in BSG solution was comparable to xanthan gum. The apparent viscosity of Xanthan was markedly higher but methylcellose at both concentrations had Newtonian behaivear during shear rate. with regard to the controlling role of water in oil uptake, the oil content in all coated samples was less than that of the control (uncoated potato strips). The potato strips treated with BSG 1% and 0.5% had the lowest oil uptake (0.14 and 0.16 % d.b., respectively). The highest amounts of the oil uptake were found for the control and potatoes coated with methylcellulose 0.5%, respectively. The potatoes treated with the hydrocolloids experimented showed that the moisture content in all coated samples was higher than that of the control. The samples treated with the BSG 1% and 0.5% had the highest amounts of the reduced moisture loss. Also, the samples treated with xanthan and BSG 1% had the highest total color change (∆E) and hardness. Conclusion: Results of this study showed that basil seed gum (as a novel hydrocolloid) can be suggested for coating and usage in industrial French fries production.
Mahdi Barmour; Jalal Dehghan nia; Babak Ghanbarzadeh
Abstract
The objective of this study was to evaluate the effect of process conditions and different pretreatments including ultrasound, microwave and osmotic dehydration on mass transfer and oil uptake during deep fat frying of potato slices. Ultrasound pretreatment was performed at frequency of 40 KHz for 10 ...
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The objective of this study was to evaluate the effect of process conditions and different pretreatments including ultrasound, microwave and osmotic dehydration on mass transfer and oil uptake during deep fat frying of potato slices. Ultrasound pretreatment was performed at frequency of 40 KHz for 10 and 30 minutes, microwave pretreatment was conducted at 5 W/g power and osmotic dehydration pretreatment was done in NaCl solutions with concentrations of 1 and 3 percent. Potato slices were then fried at 150, 170 and 190°C for 90, 180, 270 and 360 seconds. The results showed that ultrasound pretreatment for 10 minutes increases oil uptake of samples as compared with control sample, but when samples were exposed to ultrasound for 30 minutes, oil uptake was decreased. In addition, microwave pretreatment reduced oil uptake of potato slices insignificantly. Furthermore, osmotic dehydration pretreatment reduced oil uptake. In order to model oil uptake, experimental data were fitted with 6 models. The aforementioned models had the highest R2 and a minimum value of RMSE.
Masoud Hashemi Shahraki; Aman Mohammad Ziaiifar; Mahdi Kashani-Nejad; Mohammad Ghorbani
Abstract
Oil uptake occurs mainly during cooling immediately after frying. Post-frying centrifuge step used to remove the attached oil to the surface of friedproduct. Response surface methodology (RSM) technique was used to develop models for the responses to the centrifugal force (100, 200 and 300 rpm) and centrifugal ...
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Oil uptake occurs mainly during cooling immediately after frying. Post-frying centrifuge step used to remove the attached oil to the surface of friedproduct. Response surface methodology (RSM) technique was used to develop models for the responses to the centrifugal force (100, 200 and 300 rpm) and centrifugal time (20, 50 and 80 s), frying temperature (140, 170 and 200 C) and frying time (4, 6 and 8 min), Investigated factorsoptimized with respect totheoil and moisture contents, color and textural parameters. The models showed very well fitness with experimental data. The coefficients of obtained models with RSM, was optimized by using genetical gorithms and was observedthat GA optimized models showingbetterfitnesswith theexperimentalresults than RSM models. The resultssuggest thatpost-frying centrifuge step in300 rpm for 80 sand fryingin 175-180Cfor 7-8 minleadsto French fries withlowestmoisture and oil contentand best color and texture.
Fereshteh Dehghan Nassiri; Mohebbat Mohebbi; Farideh Tabatabaei Yazdi; Mohammad Hossein Hadad Khodaparast
Abstract
The objective of this work was to determine the effect of pre-frying elimination through the addition of methylcellulose and the influence of wheat flour partial replacement with corn flour (5 and 10%) on some quality factors of deep fat fried shrimp nuggets and compare the results with traditional process ...
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The objective of this work was to determine the effect of pre-frying elimination through the addition of methylcellulose and the influence of wheat flour partial replacement with corn flour (5 and 10%) on some quality factors of deep fat fried shrimp nuggets and compare the results with traditional process including pre-frying step. All batters showed shear-thinning behavior (n ≤ 0.624) and provided a good fit with power law model (R2 ≥ 0.979). Methylcellulose produced a significant increase in the consistency index of the batters. The highest pick-up value (57.68%) and the lowest oil content were found in 2% MC added batters that contained 5% corn flour, which was consistent with its high apparent viscosity. Results showed that the pre-frying elimination is an effective way in reducing oil content (%46) in deep fat fried shrimp nuggets.
