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High-protein biscuits made with ragi flour and oil-seed flour blends

M. P. Vaidehi, Pushpa Bharati, and Lalitha Reddy
Department of Rural Home Science, University of Agricultural Sciences, Hebbal, Bangalore 560 024, India

This paper was accepted for publication because it illustrates a point often overlooked by food scientists who are concerned with technological and nutritional aspects of new products without having a simultaneous concern for acceptability and keeping qualities. Problems with consumer acceptability or excessive cost, or both, have plagued the attempted development of leaf protein concentrates, weaning-food mixtures, and other products of good theoretical potential.

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INTRODUCTION

Millets like ragi, bajra and sorghum are staple foods for large numbers of people living in the semi-arid tropics. Ragi is an important millet of Karnataka which has the well-known advantages of slow digestibility and high calcium content. The white grain variety of ragi has been reported to have more thiamine and protein than the brown varieties [1].

The traditional method of consumption of ragi by both rural communities and the urban poor is in the form of ragi dumplings called ragimudde. Ragi flour is also used in the preparation of rotis, dose, porridge, and other foods.

TABLE 1. Combination of flours used in the biscuits with their codes

Expanding the utilization of this millet would go a long way towards providing more variety in the foods consumed by these groups. Furthermore, use of this millet may be more acceptable to many non-ragi users in the form of new products like biscuits, breads, and pastries [2].

In the present study a combination of 70 per cent ragi flours and 30 per cent oil-seed flours was substituted for maida (all-purpose flour) in biscuits. The primary purpose was to compare the acceptability of biscuits made from maida with that of biscuits made from two oil-seed flours combined with white and coloured ragi flours and their malts.

MATERIAL AND METHODS

Ragi varieties Indaf-3 (coloured) and Indaf-11 (white) were procured from the Regional Research Station, UAS, Mandya, and were cleaned and milled and passed through an 80-mesh sieve. To produce malted ragi flour both varieties of ragi were soaked for 16 hours, germinated for 48 hours, roasted slightly, milled, and passed through an 80 mesh sieve. Defatted soya and defatted peanut flours were obtained from the Krishna flour mill, Bangalore. Full-fat soya and peanut flours were prepared by turning roasted and dehusked soya beans and peanuts into powder with a hand grinder.

Weighed amounts of flour (70 per cent cereal and 30 per cent oilseed) were mixed thoroughly for use in the experimental biscuits. These biscuits were compared with control biscuits in which 100 per cent maida was used. Sixteen combinations of flours were used in test biscuits and coded as shown in table 1.

Biscuit Preparation

Hydrogenated fat (60 9) and powdered sugar (60 9) were creamed together. One hundred grams of each of the test flour blends as well as the all-purpose flour was sieved together twice with a quarter-teaspoon of baking powder and added to the creamed mixture. A firm dough was prepared by mixing manually. The dough was rolled out to 2.5 mm thickness and cut into biscuits 2.5 cm in diameter, which were placed on greased aluminium trays and baked in a preheated oven at 350°F for 12 minutes. Two batches of each kind of biscuit were baked, pooled, cooled, and stored in tin airtight containers. The biscuits were subjected to sensory evaluation within a week of preparation.

Sensory Evaluation

Coded biscuits were served to a panel of ten judges between 11 and 12 a.m. or 2 and 3 p.m. Four test samples of control biscuits were served at each session. The appearance, texture, flavour, aroma, and overall eating quality were evaluated on a 5-point hedonic scale, according to which a score of 5 indicated a very good rating, 4 was good, 3 fair, 2 poor, and 1 very poor [3]. Each type of biscuit was evaluated twice by the panel members.

Statistical Methods

A one-way analysis of variance was made for the mean scores, and the least significant difference (LSD) at the 5 per cent level of significance was calculated to determine whether any differences existed in the qualities of the biscuits studied.

Protein Content

The protein content of the raw ingredients analysed by the Microkjohidal method (n x 6.25) was used to compute the protein content of all sample biscuits 14] .

Cost

The cost of the prepared biscuits was calculated taking into consideration only the costs of the raw ingredients.

RESULTS AND DISCUSSION

The analysis of variance of the mean scores of the senory evaluation showed significant differences between the tested biscuits regarding all the sensory characteristics studied (table 2).

Defatted (DF) Soya-flour Blended Biscuits (Type A)

The results of the least significant difference (LSD) test at the 5 per cent level of significance are shown in table 3. The blend of soya flour(DF) with coloured ragi flour (A-1) was found to differ significantly from the others in appearance and texture with lower scores of 1.8 and 2.6 respectively.

TABLE 2. Analysis of variance for the sensory characteristics of biscuits studied

a. Significant at 5 per cent level.

TABLE 3. LSD for the mean scores of sensory characteristics for malt biscuits^a

a. Score system: 5 = very good; 4 = good; 3 = fair; 2 = poor; 1 = very poor.
b. Means in italics do not differ significantly at the 5 per cent level.

The aroma and overall eating quality of the blend made with white rag; malt (A-4) was between fair and good and differed significantly from other blends. The flavour of these blended biscuits, however, was rated between fair and poor.

Full-fat (FF) Soya-flour Blended Biscuits (Type B)

All four combinations of full-fat soya-flour biscuits differed significantly only in appearance (table 3). Only the combination with coloured ragi flour (B-1) was given a rating in this category.

Defatted (DF) Peanut-flour Blended Biscuits (Type C)

The defatted peanut-flour combination biscuits did not differ significantly from one another in aroma, flavour, and overall eating quality: the scores were between fair and poor (table 3). The appearance of the white ragi flour biscuits (C-2) and the coloured ragi-malt-blended biscuits (C-3) was rated the same. The C-4 biscuits with white ragi malt had a comparatively better appearance than the others. The texture of white ragi-flour blend biscuits was poor, while that of the others was fairly good.

Full fat (FF) Peanut-flour Blended Biscuits (Type D)

The appearance of the biscuits made with full-fat peanut flour mixed with either white ragi (D-2) or coloured ragi malt (D-3) was fairly good, while that of those made with coloured ragi flour (D-1 ) was poor (table 3). The aroma and overall eating quality of the D-2, D-3, and D-4 biscuits were fair. For flavour, D-2 and D-3 biscuits scored between fair and good (3.6), differing significantly from the D-1 and D-4 biscuits, which were rated between poor and fair.

Overall Evaluation

None of the test biscuits received scores equal to those for the control biscuits in any of the sensory categories tested. The control biscuits were always rated between good and very good.

When the pooled means for all the sensory characteristics studied are taken into consideration for all the combination flour (test) biscuits, the peanut flour blends with either coloured ragi malt or white ragi flour proved to be the best, with overall scores of 3.5 and 3.4 respectively.

The coloured ragi flour combination with any oil-seed was poorly accepted, mainly due to its dark colour. Lorenz has studied the substitution of millet flour at the levels of 5, 10, 15, and 30 per cent in biscuit preparations and reported that with increasing levels of millet flour the colour of the biscuits became darker [5]. In our study, white ragi biscuits were rated as having a better appearance.

Protein Content

The estimated protein content of the control biscuits was 6.6g per 100g biscuits. In the test biscuits the protein content was the same or better 6.6g per 100g in the full-fat peanut flour combination biscuits with coloured ragi malt, and 11.9g per 100g in the defatted peanut flour with white ragi flour. The protein content was highest in biscuits made with white ragi flours and either of the defatted oil-seed flours.

Cost

The computed cost of the test biscuits ranged from 1.05 to 1.18 rupees per 100 9, except the full-fat peanut combination with white ragi malt, which cost 1.20 rupees per 100 9. These cost estimates indicated that a greater amount of protein could be obtained with the use of a coarser millet ragi blended with the oil-seed flours in a ratio of 7:3.

SUMMARY

Sixteen types of biscuits were prepared with all-purpose flour (maida) for the purpose of comparing the acceptability of the biscuits made from maida with that of those made from combinations of one of two oil-seed flours and either the white or the coloured varieties of ragi flours and their malts. Sensory evaluation on a 5-point hedonic scale showed statistically significant differences regarding the characteristics studied. Coloured ragi malt and white ragi flour blended with full-fat peanut flour were found to be the most acceptable alternatives. White ragi malt blended well with defatted soya flour in a ratio of 7:3. The protein content of the full-fat peanut flour blend with white ragi flour was 8.0 9 per 100 9 of biscuits, whereas it was 6.6 9 for the control biscuits, which were prepared without peanut flour. The defatted soya flour combination with white ragi malt had a protein content of 11.0 9 per 100 9, which was twice the amount found in the control biscuits. A cost evaluation showed that for the same cost of regular biscuit preparation, a higher amount of protein could be obtained using 70 per cent millet and 30 per cent defatted soya or peanut flours.

REFERENCES

1. P. Pushpamma and K. Chittemma Rao, Varietal Preference, Marketing, Storage, Processing and Utilization of Sorghum and Millet in Andhra Pradesh (Andhra Pradesh Agricultural University, Hyderabad, 1980), p.1.
2.. Vogel and M. Graham, eds., Sorghum and Millet: Food Production and Use (International Development Research Centre, Ottawa, 1968).
3. A. M, Amerine, R. Pangborn, and E. B. Roessler, Principles of Sensory Evaluation of Food (Academic Press, New York, 1965).
4. Association of Official Analytical Chemists (AOAC) Official Methods of Analysis (AOAC, Washington, D.C., 1975).
5. K. Lorenz, "Protein Fortification of Cookies," Cereal Foods World, 28: 449 (1983).

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