Investigation of quality and shelf life of Fouman cookie fortified with rice bran using symmetric and asymmetric multivariate methods

Introduction: Rice is one of the most important cereals consumed in the world, especially in Asia. Therefore, the amount of bran has great importance. Rice is milled before consumption and the purpose of milling is bran separation. Bran is a brown outer subcutaneous layer of rice grain that is generally separated in multi-stage mills. Rice bran has about 13% fat. it is a natural antioxidant because of its high tocopherol content. Also, it is known as a source of frying oil due to the its low linolenic acid content. Rice bran can also greatly provide the body's need for micronutrients, amino acids and vitamins. However, attention to rice bran is more focused on its effect on decreasing cholesterol which is attributed to its soluble fibers and its lipid interference with cholesterol synthesis (Shakeri et al. 2013). Rice bran is a rich source of fiber and increases water absorption as a moisture retaining agent and increases the softness and shelf life of bakery products (Bagheri 2011). The use of bran in food or livestock products with high shelf life and industrial value requires the removal or separation of spoiling agents and contaminants. Inactivation of enzymes should be completed and irreversible (Nourizen et al. 2013). Regarding the nutritional value of rice bran, the purpose of this study was to investigate the effect of rice bran on the quality and shelf life of Fouman cookies. Results of this research will lead to produce a useful product enriched with one of the agricultural wastes of high nutritional value, increase the value of agricultural wastes and employment in this area and move towards improving the general health of society. Since very few studies have been done on the quality and shelf life of Fouman cookie, it is necessary to investigate the effect of rice bran on physico-chemical, sensory, shelf life and parameters obtained from Fouman cookie image processing. In the next step, the relationship between different characteristics of Fouman cookie was evaluated using multivariate symmetric methods including determination of correlation coefficients and analysis of principal and asymmetric indices including partial least squares regression.
Material and methods: The flour used for the production of cookies was a mixture of Setare flour of 18% and 15% of Guilan Khoushe factory (Rasht, Guilan) in equal proportions. The consumed bran was prepared as an isolated rice bran from Giltaz Company (Chaf, Guilan, Iran). Fouman pancake samples were baked at the bakery of Guilan University and transferred to the laboratory for testing. AACC (2000) methods were used to measure the moisture, ash, fat, fiber and protein content of cookies. Samples were scanned with scanner, and saved in JPEGs to evaluate the color of the samples. Imaging was performed with Canon software (version 4.9) and a resolution of 180 dpi. Then, 500 × 500 pixels’ fragments were cut from the center of the cookies and converted from RGB color space to Lab using Image J software (GJ version 1.4). To investigate other properties of crumb, the thresholding process was applied at level of 200 in black and white and the background was removed. After analyzing the components, the cavity size parameters (ratio of the number of cavities to the total surface area of the cavities) and the porosity (ratio of the total surface area of the cavities to the total surface area of the image) were obtained (Pourfarzad et al. 2009). The texture of the Fouman cookies was evaluated by a Brookfield texture analyzer model CT310K with Texture Pro CT software. A 25 mm thick aluminum probe was used for vertical shear analysis. To perform the dual compression test (TPA), the probe penetrated to 50% depth at a speed of 2 mm / s with a delay of 30 seconds between the first and second pressures. The graph was plotted by TPA graphics and calculated to measure compression, strength, adhesiveness, elasticity, and resilience. This was done on the first, third, and seventh days after production (Gomez et al. 2007). The sensory properties of the cookies were determined by Rajabzadeh (1991) method and by considering the number 1 as very bad and number 5 as very good. Eight attributes of form and shape, upper surface property, bottom surface property, cavity and porosity, firmness and softness of texture, chewability, odor, flavor and taste, and overall quality score were evaluated. Data analysis and investigation of the effect of rice bran on the sensory, chemical, image processing, and texture properties of the manufactured Fouman cookie were performed in a completely randomized design. Duncan's multiple range test with 95% confidence level was used to investigate the significance of the difference between the mean numbers after analysis of variance. Each experiment was performed in three replications. PCA and PLSR were performed on image and sensory data sets. Statistical analysis of the data was done using Minitab software (Minitab 15, Minitab Inc., State College, PA, USA).
Results and discussion: The results showed that there was no significant difference between the color score, texture and the overall quality of control and samples containing 10% bran, but their scores decreased significantly with increasing the amount of bran up to 20%. The moisture and ash contents of the samples increased significantly with increasing the amount of rice bran. Also, by adding rice bran, the parameters of crumb L, crust L, crust b, porosity and average size of Fouman cookie significantly decreased. Addition of rice bran increased the hardness of the samples on the first day, but there was no significant difference between the hardness of the control and samples containing10% rice bran during storage. The best physico-chemical, sensory properties and shelf life of Fouman cookie were obtained at 10% fortification level. Obtained Partial least squares regression models had very high R2 indicating the high efficiency of these equations in predicting the sensory properties of Fouman cookies using color analysis indices.
Conclusion: Nutrition enrichment is one of the major strategies for controlling micronutrient deficiency that is practiced in almost all countries of the world. Considering the nutritional potential of rice bran, it is necessary to pay attention to this product for its use in industrial applications, especially food industries. According to the results of this study, rice bran up to 10% is recommended. From the analysis of the principal indices analysis chart, it can be seen that improving the properties obtained from image processing has led to an increase in the sensory properties score. Among the texture characteristics, hardness on different days of storage had the highest Pearson correlation coefficients.
Keywords: Fouman Cookie, Quality, Rice Bran, Shelf Life.