The effect of basil seed gum and cress seed gum coatings on oil uptake and qualitative characteristics of fried carrot

Deep frying is commonly used in the food industry to produce a range of food products with high consumer acceptability, even though high fat contributes to obesity and cardiovascular diseases (Lumanlan et al 2019). When the food absorbs the fat, it may change the composition, texture, size, and shape of the food, resulting in loss of nutrients specifically vitamins. There is a growing interest to know the methods that could minimize the oil uptake and to reduce the fat content of fried food (Lumanlan et al 2019). Oil uptake is affected by oil quality, product and oil temperature, frying duration, initial moisture content of food ingredients, product shape and content, porosity of coating, and the method of frying (Khazaei et al., 2019). Since a high oil intake is linked to the medical risk of obesity, coronary heart disease, diabetes, hypertension and cancer, there is demand to develop products that absorb a smaller quantity of oil, leading to healthier fried foods. This has been a driving force in the food industry to develop novel products, machinery and food ingredients (Karimiet et al 2016). Using of gums to reduce the oil content is one of the simplest and most convenient methods which do not require variation in equipment design. Specifically, the hydrocolloid coatings are often known to reduce the oil uptake of fried foods. Basil seed gum (BSG) is a novel hydrocolloid extracted from Ocimum basilicum L. (Razi et al 2018), used in food product development as a gelling agent, thickener, edible film ingredient, fat replacer, and stabilizer (Razi et al 2019 a & b). Cress seed gum (CSG) (Lepidium sativum) belongs to the Brassicaceae family and is mostly cultivated in Iran, India, North America and some places in Europe. It contains a noticeable amount of D-galacturonic acid and D-glucuronic acid which makes CSG a polyelectrolyte (Gharanjig et al 2020). Nowadays, due to high-fat product problems, people are tended to produce and consume low-fat foods with desirable quality. The objective of our study was to investigate the influence of applying coatings based on BSG, CSG and a mixed solution of BSG and CSG as well as oil absorption, sensorial properties and textural characteristic of fried carrots.

BSG and CSG were purchased from Reyhan gum Persian Co., and carrot was prepared from local market. BSG and CSG solutions were prepared at concentrations of 0.5% and 1% (w/v) and 1% BSG-CSG mixture solution (1: 1 ratio). Carrots were washed and peeled and cut into 2cm. After-wards they were immediately immersed in hydrocolloid solutions at 20 °C for 2 min with a product weight to BSG and CSG solutions volume ratio of 1:3 (w/v). Frying was carried out in a controlled-temperature deep-fat fryer (Pars Khazar, Iran) filled with oil. Carrots were fried at 170 °C for 4 min. The coatings percent of samples was calculated based on adhered hydrocolloid to carrots surface. Moreover, absorbed and moisture were measured oil by using a solvent (n-hexane) and oven (105 °C), respectively. Besides, textural properties of fried carrots were measured by a texture analyzer (TA10-CT3, Brookfield, USA). Color parameters (L*, a* and b*) were measured by image j software. Sensorial properties of fried carrots were determined by a 5 point hedonic test and odor, taste, color, texture and total acceptance were measured. All experiments and measurements were carried out three times, and data were subjected to analysis of variance (ANOVA). Significant differences between means were determined by Duncan’s multiple range tests. p values less than 0.05 were considered statistically significant.

The results showed that BSG, CSG, and BSG-CSG mixture at the concentration of 1% had the highest coating percentage. Coating percentage is the amount of hydrocolloid coating adhering to the surface of carrots during immersion in the suspension prior to frying. The lowest amount of coating percentage was observed in the control sample. The moisture content of samples was determined by calculating the weight loss of the fried carrots upon drying in a convection oven at 105 °C until constant weight was reached. The control sample had the lowest moisture content and the coating increased the moisture content of the samples. Specimens coated with 1% BSG and 1% BSG-CSG mixture had the highest moisture content (p < 0.05). The lowest amount of absorbed oil was obtained in samples coated with BSG. There was no significance difference between control sample and those coated by CSG in amount of adsorbed oil. The hardness of the coated samples with 1% BSG, 1% CSG and 1% BSG-CSG mixture was significantly lower than other samples (p < 0.05). It could be due to a higher amount of moisture content at these samples. The control sample had the highest hardness value (p < 0.05). The lowest amount of L* was observed at control sample while coated samples had a higher L* value. It was higher at samples coated with 1% BSG, 1% CSG and mixture of BSG-CSG at concentration of 1%. The control sample had the highest a* value and coating with CSG and BSG decreased amount of a*. B* was significantly higher at control sample (p < 0.05) and sample that was coated with 1% BSG-CSG mixture had the lowest b* value. There was no significant difference between coated samples and control samples in sensorial properties (taste, odor, color, texture and total acceptance).

Frying is a cooking process to achieve desirable sensory attributes such as flavor, texture and appearance. One of the most important quality changes during the process is mass transfer, mainly represented by water loss and oil uptake, and heat transfer. High oil content greatly increase the risk of adverse health consequences such as obesity, high blood pressure and coronary disease Based on the results, the sample coated with 1% BSG with the lowest oil uptake and highest moisture content and overall acceptance was selected as the best sample. The control sample that was coated with water had a high oil uptake and hardness while moisture content and L* was low. The sensorial properties of all samples had no significant difference.