Biscoito tipo cookie elaborado com substituição parcial da farinha de trigo por farinha de taro (colocasia esculenta)

Abstract

Taro (Colocasia esculenta) is a plant in the Araceae family and has large heart shaped leaves with a dark green color. It has high contents of carbohydrates, proteins, minerals and B vitamins, in addition to a low fat content. It can be used as human food in the form of cooked vegetable. Its characteristics are improved when added to baked goods. Despite its potential, it is still an unknown raw material with little use in Brazil. This study aimed to develop cookie by partial replacement of wheat (Triticum aestivum) flour by taro (Colocasia esculenta) flour. The taro flour was obtained by processing the rhizomes which were purchased at a local market. The physicochemical characterization of the taro flour was conducted. The yield for each processing step and the final yield of the taro flour were determined. The taro flour showed 72.48±1.62g/100g of total carbohydrates, 10.25±0.04g/100g of proteins, 92.55±0.07g/100g of dry matter, 4.94±0.03g/100g of crude fiber, 4.32±0.01g/100g of ash and 0.56±0.11g/100g of fat. pH and water activity (aw) were 6.68±0.01 and 0.41±0.00, respectively. The acidity value was 9.68 mEq NaOH 1N/100g which represents an important factor for cookie preservation. The final yield of taro flour was 9.00±0.55%, and the largest losses occurred in the selection and the manual peeling process (28.85±9.07%). Four formulations of cookies were prepared using different taro flour concentrations, 100:0 (standard, without addition of taro flour), 90:10, 80:20 and 70:30. Physical analyses, such as yield, weight, thickness increase, diameter increase, volume, specific volume and expansion factor, before and after baking the cookies were performed. The cookies’ yield varied from 84 to 87%. The thickness increase was larger for the 100:0 and 90:10 concentrations due to the higher gluten content in these concentrations. The diameter increase among the four formulations showed no significant difference. The 90:10 and 80:20 concentrations had the lowest specific volume. The expansion factor was 9.84±0.06 and is directly related to the diameter and thickness. The cookies had a darker color (lower L* value) with increasing concentration of taro flour. Consequently, the 70:30 and 100:0 concentrations had the darkest (L*= 67.16) and the lightest (L*= 75.99) colors, respectively. As for the sensory analysis, the cookies showed difference just in the texture of the 80:20 and 70:30 taro flour formulations. The cookies had the same purchase intention what shows that the assessors may or may not buy the cookies. Thus, the chemical composition was performed only for the 100:0 and 70:30 concentrations. Ash and crude fiber increased in the 70:30 concentration, as the taro flour has a higher content of minerals and fiber. With the replacement of wheat flour by taro flour in the 70:30 concentration, the pH reduced slightly and the acidity increased. Water activity was low for both cookies. In conclusion, it was found that the addition of taro flour to the cookies slightly increased the dark color, but no significant difference was found in the sensory acceptance compared to wheat flour cookies. Therefore, it is possible to replace up to 30% of wheat flour by taro flour in the cookie formulation with regard to the sensory acceptability of the product. Additionally, it has nutritional benefits, such as increased mineral and fiber contents.