EFFECTS OF PARTIAL SUBSTITUTION OF WHEAT FLOUR WITH RICEBERRY FLOUR ON QUALITY OF FRIED DONUT

Transcription

1 EFFECTS OF PARTIAL SUBSTITUTION OF WHEAT FLOUR WITH RICEBERRY FLOUR ON QUALITY OF FRIED DONUT 1 SUPATCHALEE SIRICHOKWORRAKIT, 2 APINYA MANEEWONG, 3 APINYA KLONGCHAI 1,2,3 Department of Food Science Technology, Faculty of Science and Technology, Suan Sunandha Rajabhat University, Bangkok, Thailand 1 supatchalee.si@ssru.ac.th.com, 2 zaten_@gmail.com, 3 prawkitty16@hotmail.com Abstract- Riceberry rice (Oryza Sativa L.), a cross-bred strain from the Khao Hom Nin Rice and Khao Dawk Mali 105, was processed into flour and used to substitute wheat flour as a composite flour at different proportion of 100:0, 90:10, 80:20, 70:30, 60:40 and 50:50 (wheat flour : Riceberry flour). The formulated blends were used to produce donut. The donuts were subjected to proximate, texture, color analysis and sensory evaluation. The results of the study revealed that the ash, crude fat and crude fiber contents increased while moisture and protein contents decreased with increase Riceberry flour. The hardness of donut increased as the Riceberry flour increased, but the cohesiveness, springiness index, chewiness and specific volume decreased. Color of crust and crumb (chroma value) increased, while lightness and hue angle decreased distinctly with the addition of Riceberry flour. Overall acceptability for the 10-30% Riceberry flour additions did not differ significantly from the score of the 100% wheat. Keywords- Riceberry flour, Donut, sensory evaluation, Texture analysis. I. INTRODUCTION Rice, Oryza Sativa L., is the most important cereal crop and the staple food source consumed by over half of the world s population. Cooked rice and the rice product are generally recognized as easily digested for the human body, and non-allergic due to the ordinary composition and gluten free. Thailand produced more than million tons of rice in [1]. Although widely consumed as white rice, there are many special cultivars of rice that contain color pigments, such as black rice, red rice and purple rice [2]. Recently, purple rice have become popular due to the health-promoting effects of anthocyanins and phenolic compound [3]. Riceberry rice (deep purple grain ; Oryza Sative L.), a cross-bred strain from the Khao Hom Nin Rice variety which is well known as containing high antioxidant properties and Khao Dawk Mali 105 which is well known as a fragrant rice [4]. It contains high antioxidant contents such as -oryzanol, - tocopherol, -tocotrienol, -carotene, lutein, coenzyme Q10 [5], phenolic compounds, quercetin, isorhamnetin and other active compounds [6]. Previous studies show the incorporation of rice flour in bakery products. [7] replaced 20% of wheat flour with black rice flour in bread and there was no difference in sensory characteristics of black rice wheat bread. [8] who reported that increasing level of rice, corn and soy flour (30-50%) resulted in decreasing dough strength, extensibility and loaf volume due to the replacement of gluten by the added protein. Therefore, the objective of this project was to use Riceberry flour as an ingredient to make donut of high nutritional quality. The effect of Riceberry flour was investigated in terms of physicochemical, textural and sensory of donut. II. DETAILS EXPERIMENTAL 2.1. Raw Materials Wheat flour (UFM All Purpose Flour) was purchased from a local market in Bangkok, Thailand. Riceberry rice was purchased Chiameng Marketing Co., Ltd.. The rice was ground to flour in a grinder and passed through an 80-mesh screen. Riceberry flour was kept in sealed container at 4 C until future analysis [9]. All other chemicals used were reagent-grade Donut Preparation Wheat donut and donut with Riceberry flour were formulated Table 1. Five additional donut samples were prepared by substituting wheat flour with 10, 20, 30, 40, and 50% Riceberry flour. The donut dough was prepared using a hand-mixing the flour, sugar, salt, nonfat dry milk powder and yeast in a mixing bowl. The Egg was added and combined with the dry ingredients, followed by the water. Shortening was then added and blended in. The mixture was kneaded to form a dough and transferred to cutting board, and lightly dusted with flour. It was rolled to a thickness of about 1.0 cm and cut into a cm square. Donuts were then allowed to proof for 60 min at 35 C. Proofed donuts were fried in a deep-fryer containing 1.5 L of vegetable oil (rice bran oil) heated to 160 C. The dough was fried for 80 s on each side for a total of 160 s until it became golden brown on the outside and well cooked on the inside. The fried donuts were then drained on the strainer for 30 min at room temperature. 123

2 Table1: Recipes for donut preparation Donut Color Analysis The color of the crust and crumb donut samples was measured by spectrophotometer (Hunter Lab, Color Quest XE, USA) equipped with a D65 illuminant. Lightness, chroma value and hue angle were measured. L* value measures brightness (0-100); chroma value measures color saturation or intensity; hue angle represents the red-purple, yellow, bluishgreen and blue follow counterclockwise at 0, 90, 180 and 270 respectively of the product. All measurements were performed in triplicate Sensory Evaluation The fried donut samples were measured after 30 min of cooling. All donut samples were evaluated for color, flavor, taste, texture and overall acceptability of the samples by 30 untrained panelists which consisted of students, employee and visitors of Suan Sunandha Rajabhat University (Bangkok, Thailand) using nine-point hedonic scales, where 9 = extremely like and 1 = extremely dislike Proximate Analysis The chemical proximate compositions of Riceberry flour and donut samples were analyzed according to AOAC methods [10] Specific Volume Volume of the donut was measured using rapeseed displacement method after 60 min of frying of donuts [11]. Three donuts were put in metallic container with know volume (V). The container was topped up with rapeseed, the donuts removed and volume of the rapeseed was noted (V R ). Volume (V L ) was then calculated according to following formula: V L (ml) = V - V R Then donuts were weighed on a digital scale, W (g). Specific volume (V s ) of donuts was calculate as V s (ml/g) = V L / W 2.5. Donut Texture analysis Texture profile analysis was performed using a Texture Analyzer (Lloyd Instrument, TA plus, UK) with a maximum force of 50 N to imitate the chewing action of the teeth. An adaptor, a cylinder with a diameter of 20 mm, was used. The fried donut samples were measured after 30 min of cooling. The donut samples were compressed at the center to 50% of their original height at a test speed of 1.0 mm/s. The texture parameters, such as hardness, cohesiveness, springiness and chewiness were measured [12]. Three replicates of donut at each level of Riceberry flour were determined. Donut samples were offered in plastic white bowls coded with random 3 digit numbers. Each panelist evaluated six samples in a balanced sequential order. The optimal ratio of Riceberry flour in the donut was investigated using sensory qualities in comparison to the control donut. Sensory evaluation was repeated on two different days. III. RESULTS AND DISCUSSION 3.1. Proximate Compositions The chemical compositions and color characteristics of Riceberry flour are presented in Table 2. The moisture, crude fat, crude fiber, protein and ash contents of Riceberry flour were 5.85, 0.66, 2.76, 6.56 and 1.45 g/100 g., respectively. Color of Riceberry flour had appeared dark red-purple. Lightness, chroma value and hue angle were 42.05, and respectively. The proximate compositions; moisture content, ash, protein, crude fat and crude fiber of fried donut with added Riceberry flour and control donut are shown in Table 3. There were significant differences in the proximate compositions. The results showed that the moisture content of all donut samples was in the range of g/100 g. The moisture content decreased and crude fat content decreased when the Riceberry flour amount in the donut increased. These results are in the agreement with [13] who reported that the moisture content of donut replaced with longgrain rice flour had lower than the control donut. On the other hand protein content decreased when the Riceberry flour amount in the donut increased due to protein content in Riceberry flour was lower than wheat flour. The crude fiber and ash contents were obtained in the donut with the addition of Riceberry flour. The control sample showed the lowest while the donut containing 50% Riceberry flour possessed the highest value of the Riceberry flour, which were related to the crude fiber and ash content of Riceberry flour Table 2. The crude fiber and ash content of all donut samples were in the range of and g/100 g., respectively. 124

3 Table2: Chemical compositions and color characteristic of Riceberry flour. Table4: Color characteristics of crust and crumb donut with added Riceberry flour. Table3: Chemical compositions of donut with added Riceberry flour. significant difference. (P 0.05) 3.3. Texture and Specific Volume of Donuts The texture parameters and specific volume of donuts with added Riceberry flour are presented in Table 5. The control donut specific volume was not significantly different with addition of 10-40% Riceberry flour but it was significantly different with 50% Riceberry flour. The highest donut specific volume was 2.99 (ml/g) obtained with 0% Riceberry flour (control), while 50% Riceberry flour resulted in the lowest donut specific volume of 1.62 (ml/g). significant difference. (P 0.05) ns = no significant difference (P 0.05) 3.2. Color Characteristics of Donuts The color of the crust and crumb has been important parameter for donut with added Riceberry flour. Fried products are desirable to obtain a dark, crust, and significant limitation of product darkening could negatively affect sensory properties of the final product [14]. Color of all crust and crumb donut is shown in Table 4. The L* value indicates the lightness of the crust and crumb. As compared between wheat donut and donut supplemented with Riceberry flour, the results indicated that L* value decreased while chroma value increased as the amount of Riceberry flour increased. In donut crumb Maillard reactions are much less intense because during frying much lower temperature is obtained and a higher content of moisture of the crumb can be achieved, compared to crust [14]. Furthermore, the hue angle of all donuts supplemented with Riceberry flour had appeared more red-purplish. That was affected by the natural color of Riceberry flour used for donut preparation. The Riceberry flour used in this study has high anthocyanin pigment caused dark flour color [15]. It might be the lower levels of gluten network in the dough and consequently less ability of the dough to rise; due to the weaker cell wall structure. This is in agreement with [16] who reported that the specific volume of bread decreased as the amount of rice flour increased. Donut texture was determined as hardness, cohesiveness, springiness index and chewiness using a Texture Analyzer. As shown in Table 3, it is evident that all texture parameters of the experimental donuts were significantly different. The results shown that as the amount of Riceberry flour increased the hardness of donut increased. The hardness of control donut was not significantly different with 10-30% Riceberry flour. The cohesiveness, springiness and chewiness were significantly different with the variation of Riceberry flour content increased. The results indicated that cohesiveness, springiness and chewiness decreased as the amount of Riceberry flour increased. The springiness and chewiness of control donut were not significantly different with addition of 10-40% Riceberry flour. It might be due to the lower gluten content of those samples. The addition of Riceberry flour, a non-gluten flour, in the fabrication of donut diluted the gluten strength of the wheat flour and interrupted as well as weakened the overall structure of donut. This is in agreement with [17] who reported that the hardness of bread replaced with waxy black rice flour increased as the amount of waxy black rice flour. 125

4 Table5: Specific volume and texture characteristics of donut with added Riceberry flour. increased hardness and chewiness and decreased cohesiveness, springiness index and specific volume with Riceberry flour. Acceptable donut could be made by substitute with up to 30% Riceberry flour. ACKNOWLEDGMENTS This research was supported by Research and Development Institute, Suan Sunandha Rajabhat University. REFERENCES 3.4. Sensory Evaluation The sensory of donuts with Riceberry flour addition was done to choose the most appropriate Riceberry flour that is 10, 20, 30, 40, 50% for the formulation of the donuts. The results presented in Table 6. The donuts were evaluated for their sensory quality characteristics color, flavor, taste, texture and overall acceptability. The results indicated that color score increased with the addition of 10-20% Riceberry flour donuts and decreased by the addition of 30-50% Riceberry flour donuts. The quantity of Riceberry flour increased, the color of donuts darken which had an effect on color score decreased. The flavor score increased with the addition Riceberry flour increased due to Riceberry rice is well known a fragrant rice like Khao Dawk Mali 105. The highest taste score of donut were 8.00 obtained with 30% Riceberry flour, while control donut resulted in the lowest taste scores of donut of The texture score of control donut was not significantly different with 10-20% Riceberry flour and decreased significantly by the addition of 30-50% Riceberry flour. The overall acceptability score of control donut was not significantly different with 10-30% Riceberry flour and decreased significantly by the the addition of 40-50% Riceberry flour. This finding might conclude that using the Riceberry flour as a proportional substitution for wheat flour up to 30% could obtain the similar quality and pleasant appearance as control donut. Table6: Sensory evaluation of donut with added Riceberry flour. significant difference (P 0.05) CONCLUSIONS Higher levels of substitution of wheat flour with Riceberry flour resulted in lower moisture, crude fat and protein content and increase in crude fiber and ash content of donut. There were significant differences in lightness, chroma value and hue angle among the different levels of substitution. However, crust and crumb color was directly related to the level of substitution. Increasing the level of Riceberry flour [1]. Thai Rice Exporters Association, 2016 Thai Rice Exporters Association, Total production of Thai rice. < production.htm> (31 August 2016). [2]. C. Hu, J. Zawistowski, W. Ling, and D.D. Kitts, Black rice (Oryzasativa L. indica) pigmented fraction suppresses both reactive oxygen species and nitric oxide in chemical and biological model systems, Journal of Food Agricultural and Food Chemistry, vol. 5, pp , [3]. R. Chatthongpisut, S.J. Schwartz, and J. 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