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. |
