Production of free-gluten bread from some cereal crops

INTRODUCTION

Celiac disease (CD) is an immune-mediated enteropathy triggered by the ingestion of certain cereals, including wheat, rye, barley, triticale and oats in genetically susceptible persons (Bascuñán et al., 2017 and Leonard et al., 2017). To develop gluten-free (GF) breads for celiac patients, a number of alternative flour types, such as corn, rice, cassava, soybean, chickpea, teff and pseudocereals (e.g. quinoa, buckwheat and amaranth) have been evaluated to substitute wheat flour (Capriles and Areas, 2014; Martínez and Gomez, 2017; Sarabhai et al., 2017 and Romero et al., 2018 a). Quinoa flour is used as a food for patients suffering from celiac disease, where quinoa flour is mixed with white rice flour and yellow corn flour to increase nutritional value (Pico et al., 2017 and Romano et al., 2018 b).

Different flour types have been investigated for developing free- gluten of flat bread. Quinoa, which follows the Chenopodium quinoa Willd family, is a source of protein, mineral salts and vitamins. It is also free of gluten and therefore is considered as the suitable diet for celiac disease patients, which provides them with beneficial nutrients (Föste et al., 2014 and Peñas et al., 2014).

Rice is the seed of the grass species Oryza sativa (Asian rice) or Oryza glaberrima (African rice). As a cereal grain, it is the most widely consumed staple food for a large part of the world's human population, especially in Asia (Torres et al., 2014).

The corn is followed Zea mays L., and it is the essential item for the production of bread. Corn has become a staple food in many parts of the world, with total production surpassing that of wheat or rice (Brites et al., 2010).

The objectives of this study are to compare the influence of replacing 20%, 40%, 60% and 80% of quinoa flour with white rice flour and yellow corn on the textural characteristics of the flat bread, freshly baked and stored for 3 days, and to assess the sensory characteristics of the fresh flat bread.

MATERIALS AND METHODS

Characterization

Commercial types of quinoa flour (100 % extraction), white rice flour (100 % extraction) and yellow corn flour (97 % extraction) were milled to obtain different blends using hummer laboratory mill as presented in Table (1).

Preparation of Flat Bread

Different blends were used to prepare the flat bread, with the addition of yeast and low sugar, to activate the yeast function, with the use of boiling water temperature of 100°C (traditional method). The bread was formed and flattened manually. The dough left to ferment for 30 minutes and then bread. The following blends, which include the raw materials (quinoa flour, white rice flour and yellow corn flour) are used.

Table 1. The percentage of different experimental flour blends.

Chemical Analysis

Raw materials and blends were chemically analyzed using eleven properties. Some of the properties are related to the basic components of the grain, namely: Moisture, Protein Content, Total Fat, Total Carbohydrate, Fiber and Ash Content. The other is concerned with minerals elements, namely: Calcium (Ca), Iron (Fe), Zinc (Zn), Sodium (Na), Potassium (K). According to method described by A.O.A.C. (2005).

Preparation of Flat Bread

 Flat bread was prepared using the gelatinization method. In traditional method, (100g) of flour from any raw materials or blends were mixed with (0.5 g) salt, (1 g) yeast and (1 g) sugar. Then added 80 mL boiled water at degree up to 100 ^°C, to form dough which was divided into (50g) portions 20 Cm diameter shaping and left to ferment for 30 minutes. The dough was baked in oven at 350 °C for two min, then ventilated the bread, packed in polyethylene bags and stored at 4^oC until analyses. This coincides with the results of (Choi and Kerr, 2004).

Evaluation of Flat Bread

To evaluate the resulting bread, the sensory evaluation and the staling were doneto the flat bread.

Sensory Evaluation of Flat Bread

Flat bread was evaluated for Loaf rising, Crust Quality, Crust color, Crumb color, Odor, Taste and Crumb uniformity. The quality scoring was conducted by using a maximum of twenty a committee of experienced panelists from food technology research institute (FTRI) to evaluate organolyptically the different characteristics of flat bread. Score of each parameter as reported by Twillman and white (1988).

Staling Evaluation of Flat Bread

The staling of flat bread at different storage times 0, 12, 24, 36 and 72 h at room temperature, was tested by alkaline water retention capacity (AWRC) determination according to the method of Kitterman and Rubenthaler 1971. The loaves were dried in air oven at 35-40 °C, milled in hummer mill and passed through wire sieves with 30 mish. five grams of dried flat bread was placed into a dry plastic centrifuge tube of 50 mL capacity then, 25mL of NaHCO₃ solution (8.4 g sodium bicarbonate dissolved in one litter distilled water) was added. The tube was stoppered and shacked until all flat bread flour was wetted, the mixture left for 20 min with shacking every 5 minutes. The contents were centrifuged at 2500 r.p.m. for 15 min, the supernatant was decanted and the precipitate was left for 10 min at 45 angles (to get rid of free water). The alkaline water retention capacity (A W R C) are given using the equation: A W R C = (Weight of Precipitated of bread loves – weight of bread loaves) X 100

Statistical Analysis

All the data are analyzed using SPSS v 20. The two ways analysis of variance (ANOVA) (Blocked Design) is used to analyses the data. The null hypothesis (H₀) is that all the means are equal (there is no significant differences between the treatments), and the alternative hypothesis (H₁) is that all the means are not equal (there we a significant difference between the treatments). We accept the null hypothesis when the p-value for the interaction F-test is greater than 0.005 (P > 0.05), and reject the null hypothesis when the p-value for the interaction F-test is less than 0.005 (P < 0.05). (Kleinbaum et al., 1998 and Snedecor and Cochran, 1980. To show the relationship between the staling and its factors, a regression equation was gotten (Graybill et al., 1994).

RESULTS AND DISCUSSION

Physicochemical Properties

The physicochemical analysis for the used materials and different blends are shown in Table (2). It is noticed that, the protein content found with the highest value in the quinoa flour (14.4) and the lowest value in the white rice flour (6), while the yellow corn flour contains (6.6). To explain the result of the ash content, it must be looked into the data of the total fiber, since there is a positive relation between them. It is found that the quinoa flour has the greatest amount of the fiber (6.8), followed by the yellow corn flour (3.3) and the white rice flour has the lowest rate (2.4). Due to the bran layers has the highest mineral content. 

Table 2. Physicochemical properties of 100% extraction rate of quinoa flour, 100% extraction rate of white rice flour and 97% extraction rate of yellow corn flour and different blends.

Source: prepared by the researcher based on the results of the experiments.

Sensory Evaluation

The objective of sensory evaluation method is to measure the human response to product characteristics that can be perceived by the sense evaluation. Seven characteristics of sensory evaluation were evaluated by twenty panelists. The seven characteristic are: Loaf rising, Crust Quality, Crust color, Crumb color, Odor, Taste and Crumb uniformity. Results of sensory evaluationof flat bread prepared with quinoa flour 100% extraction rate blended with yellow corn flour 97 % and white rice flour 100 % extraction rate are shown in Table (3).

Table 3. Sensory Evaluation of flat bread prepared from quinoa flour 100% extraction rate blended with yellow corn flour 97 % and white rice flour 100 % extraction rate.

Source: prepared by the researcher based on the results of the experiments

From the statistical analyzed for the three raw materials (thequinoa flour, the white rice flour and the yellow corn flour), it is found that allthecharacteristics have significant differences (P < 0.05). while, when using the multiple comparisons, it is found that there is similarity in allcharacteristics (P > 0.05) (except the crumb uniformity) between the quinoa flour and the corn flour. This similarity may be due to the composition of rice starch differs from maize and quinoa starch in terms of percentage of amylose and amylopectin.

When adding the white rice flour by ratio 80% to quinoa flour, it decreased the values of sensory to the flat bread made from this blend compared with the 20%, 40% and 60%. This decline may be due to the different in chemical composition between the white rice flour and quinoa flour. From the statistical analysis for the four different levels of thequinoa flour supplemented by white rice flour, it can be noticed that allcharacteristics have no significant differences (P > 0.05) except the crumb color (P < 0.05). While using the quinoa flour as control, it is found that allcharacteristics have significant differences (P < 0.05). When using the white rice flour as control,the crumb uniformityand taste only have no significant differences (P > 0.05). These results are consistent with Patil and Arya (2018).

Concerning to the yellow corn blends group, values indicated that when increasing the ratio of yellow corn in blends, we observe an increase in the values of all characteristics. It may be due to the chemical composition is somewhat similar between both quinoa and yellow corn, which improves the quality of the resulting bread. When comparing statistically the results of the four blends (without control) it was found that each increase in the ratio of yellow corn in the blends leads to differences between the groups except crust quality, crumb uniformity and taste. Taking quinoa or corn as a control, it is found that there is a difference in all characteristics except crust quality. This shows that the differences occur in groups with high corn ratio, these results are in agreement with those reported by Al Shehry(2016).

Adding the white rice flour by 80%, 60%, 40% and 20% to yellow corn flour, decreased the values of the sensory. This may be due to the difference in the chemical structure between white rice flour and yellow corn flour. When comparing the blends without any control, there is no significant differences in crust quality, odder and taste only. Also using white rice as control there is no significant differences in crust quality and taste. While yellow corn flour and quinoa flour are used as control, it is found that allcharacteristics have significant differences. These findings are consistent with Ávila et al. (2017).

In the blends which containing the three raw materials, we note that increasing the ratio of white rice flour and yellow corn flour lead to increasing in the values of the sensory properties. This is may be due to the effect of the white rice flour is better than the effect of the yellow corn flour. When comparing statistically the blends which contains the three types of flour with quinoa flour as control. It is noticed that all characteristics have significant differences (P < 0.05). When comparing the blends without any control, there is no significant differences in crust quality, crumb uniformity, odor and taste. While using white rice flour and yellow corn flour as control all characteristics have significant differences except crumb uniformity.

Generally, starch grains (granules) in quinoa flour are small in comparison to starch grains (granules) in both white rice flour and yellow corn flour, which means that they carry a wide range of temperatures for the process of crystallization. Therefore, the high percentage of quinoa flour in the mixture may give good characteristics to the resulting bread

Staling Evaluation

From Table (4), it is noticed that the staling for flat bread prepared from white rice flour has the maximum values, followed by the quinoa flour. While the values of that prepared with yellow corn flour are the minimum. This is may be due to that the rate of amylose and amylopectin in the white rice starch are varying than their rate in the quinoa flour and yellow corn flour, this result agrees withSeyhun et al. (2005) and Sidhu et al. (1997). These reasons may be lead to that the flat bread is more refresh than which made from corn flour.

When comparing the different blends, it is found that the values of stalling are improved by increasing the ratio of white rice in the blends.

This means that the greater the proportion of rice flour in the produced bread, the more it will be freshness in other blends.

The regression equation is

y = 368.725 + 0.29 Q + 0.23 R - 0.041 C - 1.697 hours.

Where:y is the staling values (the dependent variable). The independents variables are: Q: the proportion of quinoa flour. R: the proportion of white rice flour. C: the proportion of yellow corn flour. hours: time of staling .

Table 4. Staling of flat bread prepared with 100% extraction rate of quinoa flour, 100% extraction rate of white rice flour and 97% extraction rate of yellow corn flour and different blends.

Source: prepared by the researcher based on the results of the experiments.

REFERENCES