Contents - Previous - Next

This is the old United Nations University website. Visit the new site at http://unu.edu

Processing and utilization quality

With the improvement in grain plumpness and test-weight, an appreciable increase in processing and utilization quality has been achieved. Flour extraction per cent-an economic factor in the milling industry-has improved from less than 60 per cent to over 65 per cent on average, and up to 71 per cent in specific cases. This top level is comparable to that of good bread wheats.

Similarly, water absorption and loaf volume are considered very important factors in the baking industry. Until 1975 most triticale strains produced breads of low loaf volume (less than 500 cc vs. more than 800 cc for good bread wheats) with undesirable crumb structure. At present, a large number of triticale lines yield a loaf volume of over 600 cc and up to 760 cc. In addition, mixtures of good triticale and bread wheat are suitable for bread manufacturing. An excellent bread quality can be obtained with a mixture of 60 per cent triticale and 40 per cent bread wheat

TABLE 5. Processing and Utilization Quality Characteristics of Selected Triticale Lines

Other food products such as flat, unleavened bread, like tortillas and chapati, or cakes, cookies, etc., can be satisfactorily made from triticale flour using suitable technology. A group of advanced lines selected on the basis of their processing and utilization quality characteristics are presented in Table 5.

Nutritional Quality

The emphasis put on developing highly fertile triticales with higher test-weights and plump kernels resulted in a decrease in the percentage of protein, from an average of 17.5 per cent in 1968 to 15 per cent in 1970. The protein content tended to drop with the increased yield levels. Although yields have continued to improve, the protein content has remained relatively stable, at substantial increase in protein yield per hectare (Figure 2).

Lysine is the first limiting amino acid in cereal proteins. Triticale protein is also deficient in lysine; however, this varies widely and it is thus possible to select and recombine improved types. The average lysine content in the 1968 crop was 2.83 per cent, ranging from 2.56 to 3.28 per cent. The 1976 - 1977 crop averaged 3.4 per cent lysine, with a range from 2.8 to 3.7 per cent. Some data are presented in Table 6.

FIG. 2. Grain Yield vs. Percentage of Protein in Triticales at CIMMYT, 1967 - 76

TABLE 6. Triticale Strains Selected on the Basis of Protein Percentage and Protein Quality

TABLE 7. Amino Acid Composition of Maize Samples Used in Nutrition Studies (9/16 9 nitrogen)

TABLE 8. Amino-Acid Composition of Triticale and Wheat Samples (9116 9 nitrogen)

Prospects for Triticale

The distribution of triticale nurseries internationally has exposed the crops to various environments, diseases, and climatic and soil conditions that differ from one place to another. The soil conditions under which triticales are grown are important; triticale seems to be highly adapted to low phosphorus, acid soils rather than to saline soils. Areas having proper soil conditions will probably be very satisfactory for the cultivation of triticales in the near future. In these and other areas where triticale has performed better than existing cereal crops, many tests on its utilization have been conducted with satisfactory results. This, combined with the superiority in protein and lysine content over some other cereal grains, suggests a potential for regions where cereals form a major part of the human diet. The nutritional quality and ability of triticale to be used as a forage crop is also being explored by many countries.

Biological Evaluation

Some of the most promising advanced materials (maize and triticale) that were previously selected through chemical analysis have been biologically evaluated at the National Institute of Animal Science in Copenhagen, Denmark. Amino acid composition of the materials tested is presented in Tables 7 and 8.

Maize Evaluation

Groups of five Wistar male rats weighing approximately 75 9 were used in these experiments, in which a preliminary period of four days and a balance period of five days were employed. Each animal received 150 mg N in 10 g dry matter daily throughout the preliminary and balance periods. Feeding took place once a day. The N was adjusted by using an N-free mixture.⁶

The response criteria are true digestibility (TD), biological value (BV), and net protein utilization (NPU). TD is the percentage of nitrogen intake absorbed by the animal or human subject. In cereal grain protein TD is known to be between 80 and 90 per cent. The maize samples show higher values (95.3 to 96.6 per cent). Less than 5 per cent of the dietary nitrogen was unabsorbed by the rats (Table 9).

Because BV is that part of absorbed nitrogen retained in the test animal, it indicates protein quality. The respective values are fairly high, between 72 and 78 per cent. The BV levels agree very well with the lysine values of the respective samples, being higher in the samples with higher lysine content (more than 4 per cent).

It should be mentioned that in the group of the three top samples (A, E, F) one is a soft endosperm type (A); the others are hard endosperm types. The hard endosperm samples also performed well. It is satisfying to see that the nutritional quality of the hard endosperm types is as good as that in the soft. In addition, hard endosperm varieties have more desirable kernel characteristics and consequently good acceptability, and are by far superior in nutritional quality to normal maize.

Samples of five triticales and one bread wheat, selected through chemical analysis on the basis of good agronomic traits and adaptability rather than for quality, were submitted for feeding studies. Data on essential amino acids in the samples are presented in Table 8. In general, essential amino acid content is slightly higher in triticale, especially lysine. However, as shown in data obtained in the nutrition studies, lysine is still the limiting amino acid in all samples.

TABLE 9. True Digestibility (TD), Biological Value (BV), and Net Protein Utilization (NPU) for Seven Maize Types

In contrast to rye protein, which is known to poorly digested-only about 75 to 80 per cent-wheat protein is highly digestible. The TD values of the wheat variety Hermosillo-77, as well as of the triticales, are high and close together-between 91 and 93 per cent-which is normally the range of wheat protein (Table 10).

The BVs, indicating protein quality, show differences that agree strongly with the corresponding lysine levels; the wheat check as well as the triticale Panda, which are relatively low in lysine, also show lower BVs compared with Beagle, which has 3.3 per cent lysine in its protein.

Concluding Remarks

Progress in improving protein quality in maize and triticale during the last five years can be summarized as follows.

In maize

• Considerable progress has already been made in developing quality protein materials that approach normal materials more nearly in kernel appearance and performance, including yield performance.
• Simultaneously, new laboratory techniques have been devised to assess quality characteristics. Laboratory activities are supporting breeding work in many countries.
• The BV of hard endosperm materials, as shown in a previous section, is comparable to that of soft endosperm Opaque-2, and quite superior to that in normal maize.

In triticale

- The total protein content and quality in triticale are slightly higher than those in wheat grown under the same conditions.

-The digestibility of triticale protein is comparable to that of wheat protein, and superior in its BV.

- Triticale is now a new crop alternative for food production in many regions of the world.

TABLE 10. True Digestibility (TD), Biological Value (BV), and Net Protein Utilization (NPU) for Five Triticale Samples and One Wheat Sample

References

1. E.T. Mertz, L.S. Bates, and O.K. Nelson, "Mutant Gene that Changes Protein Composition and Increases Lysine Content of Maize Endosperm," Science, 145: 279 (1964).

2. S.K. Vasal, CIMMYT Maize Annual Report (1977).

3. E. Villegas and E.T. Mertz, in Chemical Screening Methods for Maize Protein Quality at CIMMYT, CIMMYT Res. Bull. No. 20 (Mexico, D.F., 1971).

4. R. Mossberg, "Evaluation of Protein Quality and Quantity by Dye-Binding capacity A Tool in Plant Breeding", in New Approaches to Breeding for Improved Plant Protein (IAEA, Vienna, 1969).

5. M.M. Kohli and F Zillinsky, CIMMYT Report on Wheat Improvement (1977)

6. B.O. Eggum, "A Study of certain Factors influencing Protein Utilization in Rats and Pigs," Applied Research Laboratory Report No. 406, state committee on Animal Husbandry (Copenhagen, Denmark, 1973)

Contents - Previous - Next