Rice Science, 2010, 17(1): 51−59
Copyright © 2010, China National Rice Rearch Institute. Published by Elvier BV. All rights rerved
DOI: 10.1016/S1672-6308(08)60104-3
layoffOptimization of Bread Preparation from Wheat Flour and Malted Rice Flour Subajiny V ELUPPILLAI1, Ketheeswary N ITHYANANTHARAJAH2, Seevaratnam V ASANTHARUBA1, Sandragarampillai B ALAKUMAR2, Vasanthy A RASARATNAM2
(1Department of Agricultural Chemistry, Faculty of Agriculture, University of Jaffina, Sri Lanka; 2Department of Biochemistry, Faculty of Medicine, University of Jaffna, Sri Lanka)
Abstract: The feasibility of partially replacing wheat flour with malted rice flour in bread making was evaluated in veral formulations, aiming to find a formulation for the production of malted rice-wheat b
read with better nutritional quality and consumer acceptance. The whole grains of a local rice variety (Oryza sativa L. subsp. indica var. Mottaikaruppan) were steeped in distilled water (12 h, 30°C) and germinated for 3 days to obtain high content of soluble materials and amyla activity in bread making. The quality of bread was evaluated by considering the physical and nsorial parameters. When the wheat flour was substituted with malted rice flour, 35% substitution level and the malted rice flour from 3 days of germination was the best according to the physical and nsory qualities of bread. The quality of bread was improved by the addition of 20 g of margarine, 20 g of baking powder and 20 g of yeast in 1 kg of flour. Among different ratios of yeast and baking powder, 2:1 was the best. Bread improver containing amylas and oxidizing agents at the concentration of 40 g/kg was lected as the best concentration. When comparing the final formulation made in the bakery with wheat bread, malted rice-wheat bread contains more soluble dietary fiber (0.62%), insoluble dietary fiber (3.95%), total dietary fiber
(4.57%) and free amino acid content (0.64 g/kg) than tho in wheat bread (0.5%, 2.73%, 3.23% and 0.36 g/kg,
respectively).
Key words: rice; bread; malted rice flour; wheat flour; physical parameters; nsorial parameters
festival怎么读Bakery foods are the major cereal products available to consumers and bread has been the principal food in over half of the countries around the world [1]. Due to the increa in the involvement of females in labour market, bread plays an important part as breakfast food among urban Sri Lankan populations. Wheat is not grown in Sri Lanka becau the soil and climatic conditions are not suitable. Therefore, total requirement of wheat is fulfilled by importation. Nowadays the increasing price of wheat grain in the world market forces Sri Lanka to find other locally available raw materials for bread making.
Alternatives for wheat flour such as germinated and non-germinated soy bean flour [2], malted and fermented sorghum [3], banana flour [4],composite flours of wheat, plantain and soybeans [5], maize-soybean flour blends [6],cassava[7], rice flour, corn starch and cassava starch [8-9], rice, corn and soy flour [10] and rice flour [11-14] have been reported. A part of wheat flour was substituted with rice flour at the levels of 50, 100, 150 and 200 g/kg for bread making and the overall acceptability of the product was the best when wheat flour was substituted with rice flour up to the 150 g/kg replacement [14]. Another study revealed that the incorporation of rice, corn and soy flour in wheat up to a level of 10% produced the bread without any negative effect in quality attributes, while 30% and 50% substitution levels had very low scores for the acceptability [10]. When the whea
t flour was substituted with plantain flour at the levels of 5%, 10%, 20% and 30%, breads with acceptable qualities were formulated when the wheat flour was substituted with plantain flour only up to 20% level [4]. Wheat flour can be substituted with cassava flour only up to 20% [7].
Among the cereals, wheat and rye contain the protein called ‘gluten’, which makes them superior to other cereals for the production of porous baked goods. The main function of gluten in dough during dough mixing is to swell and hold water, forming cells with strong elastic walls which capture carbon dioxide formed during fermentation [15]. Therefore, when substituting wheat flour with other flours, the amount of gluten is reduced and there will be a lack of gluten net work to capture the carbon dioxide formed during fermentation.
Received: 17 June 2009; Accepted: 31 September 2009 Corresponding author:Vasanthy A RASARATNAM ()
52 Rice Science, Vol. 17, No. 1, 2010
The rice flour is far from the ideal as the structural component of leavened bread rolls or loaves, and the rice grain contains none of the gluten which gives wheat flour its unique ability to form highly exp
anded, tender, white and flavorful yeast leavened or chemically leavened baked products [16]. However, it may be possible to u malted rice flour instead of raw rice flour in the preparation of bakery items since many changes occur in the grains during germination. During ed germination, the breakdown of ed rerves, carbohydrates and proteins takes place. Germination caus increa in veral vitamins [17]. The natural process accompanying sprouting of grains creates or releas in active form relatively large quantities of enzymes and changes the original components of the grains in many other ways [16]. Therefore, addition of malted rice flour may improve not only the nutritional quality but also the texture of breads when the wheat flour is substituted with malted rice flour.
The aim of the prent study is to evaluate the possibility of substituting wheat flour with malted whole rice flour for the preparation of bread, improve the physical and nsorial properties of malted whole rice-wheat bread and statistically establish the optimal amounts of each ingredient in malted whole rice-wheat bread, in order to produce the bread with good textural properties and nutritional value.
MATERIALS AND METHODS
Materials for bread preparation
Grains of rice (Oryza sativa L. subsp. indica var. Mottaikaruppan) were purchad from a local market and husked. The reagents ud were of analytical grade. The ingredients ud in bread making were: wheat flour, malted rice flour, table sugar, table salt (NaCl), margarine (AB Mauri Lanka, Sri Lanka), yeast (commercial strain of Saccharomyces cerevisiae of Fermipan bakers yeast from Gist-Brocades, Waterings-1, Delft-Holla, Netherlands), bread improver (SK 9000, ESS KAYE Enterpri, Kelaniya, Sri Lanka) which contains wheat flour, sugar, amylas and oxidizing agents as ingredients and baking powder (Motha Confectionary Works Ltd, Sri Lanka). All ingredients were purchad from a local market and the same trade products were ud in all experiments. Evaluation of bread quality
Evaluation of bread volume
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Volume of the bread was determined one hour
after the end of baking process using the formula:
specific volume (cm3/g) = Volume of bread (cm3) /
Dough weight (g). After weighing, the volume of the
sample was measured by the method of displacement
of millet eds [8].
Bread nsorial evaluation
Bread preparations were submitted to a nsory
analysis in order to evaluate flavor, crumb colour,
crumb texture, crust colour, crust texture and degree
of mouth satisfaction or acceptability. The bread samples
were homogenously sliced and rved with water. The
samples were prented in identical containers. Ten untrained panel members were lected from students
and staff of the Department of Biochemistry, Faculty
of Medicine, Sri Lanka to perform the evaluation
using a hedonistic scale of 5 points (Table 1). Breads prepared with different formulations were submitted
Table 1. Scores assigned for the evaluation of flavor, mouth
satisfaction, crumb colour, crumb texture, crust colour and
crust texture of the breads under different treatments.
Attribute Character Score
Flavor Sweet 1
Savor 2 Fermented
3 Raw
dough
4 Bitter
5 Mouth satisfaction Dislike very much 1
Dislike 2
Like nor Dislike 3
Like 4 Like
very
much
5 Crumb colour Reddish 1
Reddish
brown
wiperblade2 Brown
3 Light
brown
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4 White
5 Crumb texture Crumbling 1
Buttery 2 Floury 3
Soft 4 Sticky 5 Crust colour Reddish brown 1
Brown 2 Light
brown
3 Whitish
brown
4 White
5 Crust texture Brittle 1
Hard 2 Dry 3 Soft 4 Sticky 5
Subajiny V ELUPPILLAI , et al. Optimization of Bread Preparation from Wheat Flour and Malted Rice Flour 53
to an acceptability test using proper questionnaire. Evaluation of proximate composition
The contents of moisture (gravimetric method), total sugar [18], total protein [18], free amino acids [19], fat [18], fiber [20] and ash [18] of the final bread formulation were evaluated. Malting of rice grain
Husked and unpolished rice grains were steeped in distilled water (grain to water ratio is 1:2) at 30°C for 12 h and germinated for 3 days in a sterile moistened cloth bag kept in dark. Moistened conditions were maintained throughout the germination period by spraying distilled water. The grains were dried under the sun to arrest germination and the dried grains were
pulverized in a domestic grinder at 30°C to obtain malted rice flour.
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Bread making with traditional ingredients
Bread making started from a basic formulation (BF) given in Table 2. Breads were baked for 40 min at 230°C. All the experiments were performed in triplicates.
Bread making with malted rice flour by altering the formulation
First the breads were prepared from wheat flour substituted with different amounts of malted rice flour, and then the malted rice flour obtained after different days of germination were tested to find out the effect of malting in the preparation of bread. Subquently,
Table 2. Amount of ingredients ud in different experiments.
Factor changed in the formulation Formulation No. Wheat flour (%) Malted rice flour (%) Baking powder
(%) a
Yeast
(%) a
Fat (%) a
Bread improver (%) a Days of germination (d)
Basic formulation BF 100 - 0 1 2 1 -
I-a 100 0 - 1 2 1 - I-b 90 10 - 1 2 1 4 I-c 80 20 - 1 2 1 4 I-d 70 30 - 1 2 1 4 I-e 65 35 - 1 2 1 4 Malted rice flour
I-f 60 40 - 1 2 1 4 II-a 65 35 - 1 2 1 1 II-b 65 35 - 1 2 1 2 II-c 65 35 - 1 2 1 3 II-d 65 35 - 1 2 1 4 Days of germination
II-e 65 35 - 1 2 1 3 III-a 65 35 - 1 1 1 3 III-b 65 35 - 1 2 1 3 III-c 65 35 - 1 4 1 3 III-d 65 35 - 1 6 1 3 Fat
III-e 65 35 - 1 8 1 3 IV-a 65 35 0 1 2 1 3 IV-b 65 35 2 1 2 1 3 IV-c 65 35 3 1 2 1 3 IV-d 65 35 4 1 2 1 3 Baking powder
IV-e 65 35 5 1 2 1 3 V-a 65 35 2 1 2 1 3 V-b 65 35 2 2 2 1 3 V-c 65 35 2 3 2 1 3 V-d 65 35 2 4 2 1 3 Yeast
V-e 65 35 2 5 2 1 3 VI-a 65 35 2 2 2 1 3 VI-b 65 35 1 2 2 1 3 VI-c 65 35 0 2 2 1 3 VI-d 65 35 2 0 2 1 3 VI-e 65 35 2 1 2 1 3 Ratio between optimum amount of baking powder and yeast
VI-f 65 35 1 1 2 1 3 VII-a 65 35 1 2 2 0.5 3 VII-b 65 35 1 2 2 1 3 VII-c 65 35 1 2 2 2 3 Bread improver
VII-d 65 35 1 2 2 4
3
a
giffgaffPercentage of flour.
To all bread formulae, 1.67 g of salt and 3 g of sugar were added.
54 Rice Science, Vol. 17, No. 1, 2010
different bread formulations were tested by changing the amount of an ingredient at a time to get optimum amount of each ingredient (Table 2). Breads were evaluated for the physical and nsorial properties. Specific volume and nsory qualities of the breads were determined.
Comparison of malted rice-wheat bread with wheat bread
Malted rice flour-wheat bread and wheat bread made in the bakery were compared by analyzing specific volume and proximate composition. Breads also were submitted to nsory evaluation to evaluate flavor, crumb colour, crumb texture, crust colour, crust texture, degree of mouth satisfaction and over all acceptability by asking the degree of likeness. The scores assigned for each attribute are: 1, Dislike very much; 2, Dislike; 3, Like nor Dislike; 4, Like and 5, Like very much. Statistical analysis
Results obtained for specific volume, moisture content and proximate composition of breads were statistically analyzed by ANOVA and nsorial data were statistically analyzed by the Friedman test using the SAS analytical package.
RESULTS
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Effects of different concentrations of malted rice flour on bread quality
Malted rice flour from four days of germination was ud for the preparation of bread. Considering the substitution of wheat flour with malted rice flour,
difference in specific volume was significant (P <0.05) under all the different substitutions considered.
The highest specific volume (4.71 cm 3/g) was obtained for 100% wheat bread (Formula I-a) and the specific volume of the breads decread significantly (P <0.05) from 4.57 to 2.95 cm 3/g whereas the moisture content of the breads was incread as the substitution level increas. Regarding moisture content, significant increa (P <0.05) from 29.4% to 33.4% with increasing level of malted rice flour was en.
Extreme outliers in the results were omitted for the analysis. The nsory analysis showed no significant differences (P >0.05) for the attributes of flavor and crust texture of the malted rice flour-wheat bread compared with 100% wheat bread, while significant differences (P <0.05) for the attributes of crumb colour, crumb texture, crust colour and degree of mouth satisfaction (Fig. 1-A). Crumb colour and crust colour were incread from whitish to reddish with increasing level of malted rice flour substitution. Bread with the 40% (Formula I-f) substitution level produced sticky crumb texture and the lowest scores for mouth satisfaction. Even though the 35% substitution level (Formula I-e) had low level of mouth satisfaction and low specific volume, by considering the nutritional value, this formula was lected for further studies to improve the taste and specific volume. Effects of fat content on bread quality
The specific volume was incread significantly (P <0.05) from 3.8 to 3.9 cm 3/g when the fat conten
t of flour was incread from 10 to 20 g/kg. After that, with increa in the amount of fat, the specific volume
decread, but the decrea was not significant
Fig. 1. Effects of different contents of malted rice flour (A) and fat (B) on the mean scores for the attributes of flavor, mouth satisfaction,
crumb colour, crumb texture, crust colour and crust texture of breads.
Subajiny V ELUPPILLAI , et al. Optimization of Bread Preparation from Wheat Flour and Malted Rice Flour 55
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(P >0.05) for 40 g/kg (Formula III-c) and 60 g/kg of flour (Formula III-d). Moisture content of the breads under different treatments ranged from 29.47% to 29.88% and did not differ significantly (P >0.05) among treatments. Sensory analysis (Fig. 1-B) showed that a significant difference (P <0.05) was obrved only for crumb texture. The crumb texture became sticky as the fat content increas. While other attributes such as flavor, crumb colour, crust colour, crust texture and mouth satisfaction did not differ significantly (P >0.05) among treatments. Bad on the results, the fat content of 20 g/kg of flour (Formula III-b) was lected as the best one.
Effects of malting time of rice on bread quality Significant differences (P <0.05) in specific volumes were obrved among the breads made from rice flour malted for 0 (raw rice) (Formula II-a), 1 (Formula II-b) and 2 days (Formula II-c), whereas the specific volume of breads made from rice flour malted for 3 (Formula II-d) and 4 days (Formula II-e) did not differ significantly (P >0.05). The specific volume incread from 2.3 to 3.8 cm 3/g with the increa in the germination time.jamescameron
Moisture content (ranged from 29.82% to 30.05%) and all the attributes of nsory evaluation showe
d no significant difference (P >0.05) among different treatments. Mean score obtained for the attributes of different treatments are shown in Table 3.
Effects of baking powder on bread quality
The specific volume showed a significant decrea
(P <0.05) from 3.91 to 3.31 cm 3/g with increasing levels of baking powder whereas the moisture content (ranged from 30.37% to 32.20%) did not differ significantly (P >0.05). Sensory evaluation showed no significant difference (P >0.05) for flavor and crumb colour among the treatments. Other attributes such as crumb texture, crust colour, crust texture and mouth satisfaction differed significantly (P <0.05) among the treatments (Fig. 2-A). Crust colour was incread towards reddish with increasing level of baking powder. Baking powder at the level of 20 g/kg of flour (Formula IV-b) produced soft crumb texture. Comments showed that baking powder at the levels of 30 (Formula IV-c), 40 (Formula IV-d) and 50 g/kg of flour (Formula IV-e) gave bitter taste. The Formula IV-b showed a higher score for the degree of mouth satisfaction than the control (without baking powder). Therefore, the Formula IV-b was lected as the best one.
Effects of yeast concentrations on bread quality
In order to find out the optimum concentration of
Table 3. Effect of germination days of malted rice on the mean
scores for the attributes of flavor, mouth satisfaction, crumb colour, crumb texture, crust colour and crust texture of breads. Germination time (d) Flavor
Mouth satisfaction Crumb colour Crumb texture Crust colour Crust
texture
0 3.0 3.6 4.0 4.1 2.9 1.0
1 3.0 3.5 4.1 4.0 2.9 1.0
2 3.0 3.7 4.1 4.0 3.0 1.1
3 3.0 3.8 4.0 4.1 2.9 1.2
4 3.0 3.9 4.1 4.1 2.9 1.0
The ratio of wheat flour and malted rice flour is 65:35.
Fig. 2. Effects of addition of different amounts of baking powder (A), yeast (B) and different ratios between optimum amount of yeast (20
g/kg) and baking powder (20 g/kg) (C) on the mean scores for the nsory attributes of flavor, mouth satisfaction, crumb colour, crumb
texture, crust colour and crust texture of breads.
