TESTING OF NEW-ZEALAND-GROWN WHEATS.

New Zealand Journal of Agriculture, Volume XXVII, Issue 2, 20 August 1923, Page 89

TESTING OF NEW-ZEALAND-GROWN WHEATS.

II. STRENGTH OR QUALITY OF FLOUR.

L. D. FOSTER,

Analyst, Chemistry Section, Wellington.

The best wheat is that one which will produce the greatest amount of flour of the best quality. In the previous article, printed in last month’s Journal, the amounts of flour obtained from wheats grown in various localities in New Zealand were considered. Yield of wheat per acre and yield of flour are indeed important considerations ; the miller, however, has to supply the market with a product of as good quality as possible. He judges a flour largely by colour, strength, and weight, of flour per bushel of wheat. By blending the very best wheats with more average samples he endeavours to maintain a satisfactorily high standard, and one z which satisfies the requirements of the baker and the consumer. Since it is the quality or strength of the flour which really determines the demand and the value of a wheat, this factor of strength is no less important than those other considerations. A strong wheat has been defined as one which yields flour capable of making well-piled loaves.

The strength of flour, then, is its apparent and potential ability to produce a large loaf of good texture : a hard wheat will generally produce a strong flour, a soft wheat a weak one. It is a well-known fact that, if the starch is carefully washed away from flour a curious plastic elastic mass remains. This is the so-called gluten, which is a mixture of two nitrogenous chemical compounds, ’gliadin and glutenin. Gluten imprisons gas generated by the fermentative processes due to the addition of yeast, and in this way enables a loaf to retain, after baking, that texture so characteristic of well-baked bread. Many attempts have been made to correlate strength with any one constituent as determined by chemical analysis. For many years discussion of strength centred on ' whether the protein (or gluten) content of a flour was or was not a true indication of this quality. Proteins, it will be remembered, are . a group of compounds present in plant (and animal) tissues, easily assimilated by the body and contributing to the formation of muscle, &c. It was at first thought that the amount of gluten (which is very closely related to the total amount of protein) was the controlling factor ; then the idea became general that the quality of the gluten was all-important and the quantity rather negligible. Many other factors which ■ at first sight have appeared rather contradictory have been considered at length, and in the light of fuller knowledge found often to be supplementary in character rather than otherwise. It is true that much remains to be done ; at the same time it is likely that the truth lies between many divergent statements of fact and of theory. Stockham (1) thinks that the total quantity of gluten present is important, and that a consideration of quantity no less than quality is essential to an understanding of strength. In applying the statistical method Zinn (2) has compiled a large amount of published data on the

chemistry of wheat, and computed the coefficients of correlation for the important chemical characters; he has shown that there is a very close connection between quality, quantity, and amount of gluten present.

Another method of arriving at the strength of flour is to determine the amount of water retained by the gluten extracted from any sample (3). In New South Wales the proportion of water taken up by the flour itself has been regarded as a good indication of strength (4). Lastly, the percentage of ash serves, among other things, as an indication of the skill of the miller (5 and 6).

These methods may not apply equally to wheats grown under New Zealand conditions. But even if no single property is an unfailing measure of strength, it is probable that from a consideration of several a very good idea of the quality may be obtained. Only by further investigation of varieties grown under local conditions, and collection of data obtained from them, will more information be obtained.

It was pointed out in the previous article that the cause of strength, or lack of it, is due to three main factors—climate, soilfertility, and variety. Fertility, of course, affects yield of wheat, but apparently not strength of flour (7 and 8). There remains the varietal factor, and there is no doubt that strength may ’ often be improved by proper selection and breeding.

EXPERIMENTAL WORK

Some sixty-six samples were milled in this Laboratory, and further examination was made as to the probable strengths of the resulting flours. A selection of the results obtained is tabulated in the accompanying Table II. •

It is to be regretted that only a few samples of Pearl were received. It will be remembered that this variety gave as a rule a very good yield of flour. Referring to Table II, it will be seen that the sample with the lowest percentage of flour (P 305) contained the most valuable amount of protein ; but the other three samples — on the other hand, all yielded very good amounts of flour —were all very close in protein content to the highest. The amount of water absorbed per cent, of flour reached a good average in these samples. It will be seen that the amount of dry gluten was approximately the amount of total protein present; the ratios of wet to dry gluten showed considerable divergence, but in view of the small number of samples received nothing further can be said on these figures.

A more satisfactory number of samples of Velvet was received. The sample giving the second highest yield of flour (P 294) also contained 15-75 per cent, of protein, which is a remarkably good figure. Its water-absorption figure was also high, and the ratio of wet to dry gluten was satisfactory. This wheatfrom Dumbarton,* near Roxburgh —appears to be a wheat of all-round excellence. It is followed closely by three samples which also showed very' good protein content. Of these three it appeared that the lowest in protein

was probably the best all-round wheat, a conclusion that was arrived at from a consideration not only of the protein present, but also of its very good milling-properties. Its capacity for water was also higher than that of the other two. All three, however, were very good wheats. The three remaining samples were fairly good wheats and better than the average ; O 814, however, was rather low in its milling - properties. Velvet, then, in 1922, was an all-round good variety. The absorption-of-water figure was always high, a fact of much' interest and importance to < the baker. This variety also gave a good average yield of flour per bushel. Lastly this is always important —the average protein content was good, and, when, grown in some localities, excellent. In this respect it is interesting to note the very . good sample of wheat from Dumbarton, and the high average of the three samples from the Upper Taieri, districts near the borders of the area of lowest rainfall in New Zealand. As a variety, Velvet would be classified in Australia as a “ medium strong ” wheat. There is no doubt that at least four individual samples among those now under discussion might with justification be classified as “ strong ” wheats.

Three samples of College Hunters were good wheats, and might be called medium strong; the fourth was a medium wheat with 9-54 per cent, protein. The best of these was from Dumbarton, with a yield of 73-6 per cent, flour, and containing 10-94 per cent, protein ; its capacity for water and the ratio of wet to dry gluten were both good.

The best of three samples labelled Tuscan came from Malaghan’s, Lake County, part of which is the driest district in the Dominion; this wheat milled well, with 72-6 flour, possessed a fair capacity for water, and contained a good amount of —quite a good all-round wheat. Two samples of White Tuscan and two samples of Solid-straw Tuscan contained moderate amounts of protein. A Purple-straw Tuscan was rather better in this respect. ’ It will be remembered that the samples of Victor gave generally very good yields of flour. In 1922, however,' they appeared in most cases to be lacking in strength, but P 322, from Domett, Cheviot, was a sample above the average for this variety.

The Miscellaneous samples gave some interesting■ results. It is true that usually only one sample of each was received ; nevertheless the information obtained is sufficient to warrant further investigation of these lesser-grown varieties. One of the outstanding samples milled in 1922 was the Burbank's Super, grown at Flaxton, Eyre. It is said that this variety compares favourably with other wheats in yield per acre, and that its chief characteristic is early maturity. This particular sample milled rather poorly, with 70 per cent, of flour but it more than made up for this deficiency by its protein content, which was as high as 14-44 P er cent. This is nearly 1 per cent, higher than the average of the strong red wheats exhibited during recent years at the New South Wales Royal Agricultural Society’s show at Sydney (9). The absorption figure was very good, and, although the ratio of wet to dry . gluten was unexpected, it was observed that the physical condition of the extracted gluten was better than is usually the case. One cannot, of course, judge a variety by one sample, but the figures undoubtedly show that the adaptability of the variety to local conditions is well worth looking into.

From a sample of Huron (apparently a Canadian wheat), grown near Dumbarton, results as interesting as those of Burbank's Super were obtained. Its milling-yield (74-9 per cent, flour) was very good, and, in addition, its protein content reached the high figure of 12-69 per cent. This is an-excellent strong sample.

A sample of Thew, also from Dumbarton, milled moderately well, and contained a very good amount of protein (12-50 per cent.); it had a fair capacity for water, and the ratio of wet to dry gluten was satisfactory. It might be classified as a medium-strong wheat. In the same class might be placed the sample of Rymer (grown at the same place), which is a rather poor milling-wheat but one of good strength (12-25 per cent, protein) ; it is also classified in New South Wales as of medium strength.

Marquis, originally a Canadian variety, is now extensively grown in Australia, where it is classified as a strong red wheat ; in certain American States it fetches highest prices (10). The one sample tested here hardly maintains that high level, but its milling-yield is good, and it still contains a good percentage of protein.

John Brown, from Winton, yielded only 70 per cent, of flour, but it possessed a good amount of protein, and appears to be a mediumstrong wheat. It is interesting as being a Farrer cross, which in Canada has the reputation of being a strong wheat with . a good average yield per acre, and giving better all-round results than many Canadian varieties.

Two good all-round samples are those of Dreadnought, grown in Waitaki County. Both gave very good milling-yields, and both contain good percentages of protein, being medium-strong wheats well above the average.

VARIETIES AND LOCALITIES.

In grouping the 1922 samples into districts it must be remembered that at present, because - of lack of sufficient data, no general comparison between varieties is possible. In a few cases, however, the results do seem to point to one or two outstanding characteristics which should be noted.

Nine samples were received from the drier parts of the TuapekaUpper Taieri districts. Here the very well defined good quality of these wheats and the high average which they maintain are clearly apparent. Not only are they good milling samples, but five appear to be strong wheats, while four of them are medium-strong samples. Some of them are not widely known in New Zealand, and only further experiment will show if they can maintain this standard. It is probably no coincidence that three samples of Velvet occupy prominent positions among this collection of strong wheats.

The Waitaki wheats contained medium-strong samples of Dreadnought. Of the others, one was a Velvet with a very good milling figure of 73-1 per cent, flour, and containing a very good amount of protein, 12-78 per cent. This could be considered a hard wheat, giving a flour of very good strength. Among the others a fair average was maintained.

From Springs County six samples were received, of which two, a College Hunters and a Velvet sample, were good medium-strong

wheats samples of Velvet (P 812) and Pearl (P 811) were .average samples. A sample of College Hunters from Ellesmere was a good wheat, with 12-19 per cent, protein. Lastly, from Eyre came the excellent sample of Burbank’s Super, referred to at length in a previous paragraph.

SUMMARY AND CONCLUSION.

Wheats may be classified into [a) strong, (&) medium-strong, and (c) weak samples.

On examining Table II it will be found that in 1922 one variety, Velvet, stands out as being generally the best wheat grown in - its district. In particular, when grown in the drier parts of Tuapeka and Upper Taieri districts bordering on the area of lowest rainfall in New Zealand, three samples of Velvet are conspicuous even among strong wheats. Varieties which, although represented often by single samples, give promise of being wheats of good strength are Burbank’s Super, Thew, and Huron. Others which appeared to be good mediumstrong wheats are John Brown, Dreadnought, Marquis, and Rymer.

It is apparent that variety has a considerable influence on strength. Some varieties maintain a relatively high standard under different environments ; such a variety is Velvet. Others show a fairly large range in protein content, some samples contai ring high percentages of protein ; but the average for such a variety may often be low. In such a case, notwithstanding these better exceptions, the variety as a whole must be regarded as a soft wheat. Only in special cases, such as suitability of climate and soil favouring production of the better samples of the variety, should such a wheat be grown—from the milling and breadmaking points of view.

Another important factor is that of climate, samples from some districts showing to distinct advantage. It will be noticed that the drier districts in general produce stronger wheats. To a marked degree this is true of Central Otago, a notably arid district, as evidenced by the samples from Tuapeka and Upper Taieri. This is what one would expect from data published in other countries where it has been observed that comparatively high temperatures, long days, and absence of excessive moisture during ripening, hasten maturation of the grain and increase its content of gluten, and hence its protein (8 and 11). There are probably other districts in the Dominion with characteristic climates which the examination of further samples will prove also to be specially adapted to the growing of strong wheats.

It is probable that no.one variety possesses combined the desired characteristics of yield per acre, protein content, Hour-yield, weight per bushel, and the required milling-qualities. Evidence may be obtained, however, by experimental milling and chemical investigation, indicating which varieties combine most of these qualities and are therefore most profitable to grow or . to use for selection.

Finally, although individual samples may often be regarded as possessing the elusive quality of strength to a marked degree, a variety may be classified as a strong or medium-strong wheat only from data obtained from many individual samples and extending over a period of years.

REFERENCES IN TEXT.

(i.) Stockham, W. L. : Some Factors related to the Quality of Wheat and Strength of Flour. Bulletin igg, North Dakota Exp. Station, 1920.

(2.) Zinn, J. : Correlations between various Characters of Wheat and Flour. Journal of Agricultural Research, 1923, p. 529.

(3.) International Review of the Science and Practice of Agriculture, Rome, 1922 P- 1331-

(4.) Guthrie, F. B. : Wheat and Flour Investigation. . Science Bulletin No. 7, Department of Agriculture, New South Wales, 1912.

(5.) Jago, W. : The Technology of Breadmaking, p. 307

(6.) Snyder, H. : Bulletin No. 85, Agric. Exp. Station, Minnesota, 1904

(7.) Humphries, A. E., and Biffen, R. H.: The Improvement of English Wheat. Journal of Agricultural Science, Cambridge, 1912, p. 1.

(8.) Shutt, F. T. : Influence of Environment on the. Composition of Wheat Journal of the Society of Chemical Industry, 1909, p. 336.

(9.) Agricultural Gazette of New South Wales, 1918, 1919, 1920, and 1921.

(10.) Experimental Station Record, 1922, pp. 131, 337.

(11.) Roberts, H. F. : The Relation of Protein Content to Variety Types. Journal of Agricultural Science, Cambridge, 1920, p. 121.

*This and all other samples from Dumbarton were grown at the Moa Seed Farm.

Laboratory ' No. . Variety. Locality Flour. Moisture. Absorption Water. Gluten, Wet. Gluten, Dry. Ratio Wet Dry Gluten. . Nitrogen. Protein. Ash. Per Cent. Per Cent. Per Cent. PerCent. Per Cent. Per Cent. Per Cent. Per Cent. Per Cent P Pearl Kowai. Balcairn, Cent. .71-0 12-92' 51-6 27-22 9'74 2-79 : 1 i-6o 10-00 0-48 71-0 Per Cent. 12’92 Per Cent. 51-6 PerCent. 27-22 PerCent. 9-74 Per Ce 2’79 nt. I Per Cent. I -6o Per Cent. 10*00 Per Cent 0-48 O Springs. 73’8 12-98 54’4 26-94 9-51 : l-S 8 9-88 0-48 I I-58 9-88 0-48 382 Lake Frankton, 74'3 13’53 56-0 24-O5 8-89 1 : 2-71 i-54 9-63 0-58 I i-54 9-63 0-58 P 307 Weedon’s, Paparua 75’2 12-83 53-o 31’35 10-12 3-10 I i-54 9-63 o-6o Velvet Weedon’s, Paparua 75’2 12-83 53-o 31-35 10-12 3-1° : 1 i-54 9-63 o-6o P 294 Dumbarton, Tuapeka 74-1 13-40 57'5 45-70 I5-84 2-88 : 1 2-52 15-75 0-67 Velvet Dumbarton, Tuapeka 74-1 13-4° 57’5 45’7° I5-84 2-88 I 2-52 15-75 0-67 P 291 Upper 72-6 13-5° 57'4 45’00 I5-65 2-88 2-38 14-88 o-54 I 2-38 14-88 o-54 290 71-8 13-67 57-o 39'73 I3-82 2-87 I 2- 1 1 13-19 0-56 Windsor Downs, Waitaki. . 71-8 I3-67 57-o •39-73 I3-82 2-87 : 1 2-XI I3-W 0-56 262 Windsor Downs, Waitaki. . 73’1 12-87 58-6 42-78 14-06 3-°4 I 2-04 12-78 0-65 » 73’1 12-87 58-6 42-78 14-06 3-04 : 1 2-04 12-78 0-65 292 Upper . 72’9 13-62 57-8 34-13 II-4I 2-99 i-8i 11-31 o-54 I i-8i 11-31 o-54 814 Springs 70-8 12-89 56-0 28-85 10-52 2-74 : 1 1-69 10-56 0-51 Doyleston, Ellesmere 70-8 12-89 56-0 28-85 10-52 2-74 I 1-69 10-56 0-51 812 O 75’2 I2-8o 57’0 30-65 10-74 2-85 I i-6i 10-06 o-59 Doyleston, Ellesmere 75’2 I2-8o 57’0 30-65 io-74 2-85 : 1 i-6i 10-06 o-59 308 College 71’5 12-73 52-2 33-57 12-77 1 i-95 12-19 0-56 I i-95 12-19 0-56 P Dumbarton, Tuapeka 73’6 13-79 54-o 32-31 11-15 1 2-90 i-75 xo-94 0-69 I i-75 10-94 0-69 T 3 Springs 71-7 13-09 50-4 34’93 n-68 1 2-99 . i-74 • io-88 0-56 I 1-74 io-88 0-56 265 Airedale, 73’0 13-18 52-4 27-73 9-65 1 i-53 9’54 0-63 I i-53 9’54 0-63 383 Tuscan Lake 72-6 13-80 53'4 32-13 11-09 2-90 1-78 11-13 o-6o I 1-78 n-13 o-6o 201 White . Marlborough 70-4 13-34 5i-4 30-21 10-44 2-89 1-64 10-25 o-59 I 1-64 10-25 o-59 P Southland Winton, 1 7 13-78 52-4 25-02 9-02 2-77 : 1-58 g-88 0-72 I 1-58 9-88 0-72 317 Solid-st Horrelville, Eyre 71-1 12-94 53-o 28-02 io-59 2-65 i-57 9-81 0-58 I i-57 9-81 0-58 Tuscan 416 Tuscan Ditto S. . Carterton, 7°’5 . 14-69 51-8 29-37 10-30 2-85 1 i-53 9’54 o-6o I i-53 9’54 o-6o 256 e-straw Avon . Windsor, 7 12-93 53'6 29-16 10-46 2-80 1 1-67 10-41 0-62 I 1-67 10-41 0-62 Tuscan P 322 Tuscan Victor Domett, Cheviot 74'4 13-04 5°-2 24-53 8-39 2-92 : 1 i-54 9-63 0-56 Miscellaneous. / Victor Domett, Cheviot 74’4 13-04 50-2 24-53 8-39 2-92 I i-54 9-63 0-56 815 Burbank’s Super Flaxton, . Eyre A 70-0 Hscellcmec 12-96 57’2 41-10 14-85 2-77 : 1 2-31 . 14-44 0-50 12-96 us. 57’2 41-10 14-85 2'77 I 2-31 14-44 0-50 P 43i Huron Dumbarton, Tuapeka 74’9 13-67 51-6 31-84 11-58 1 2-75 2-03 12-69 o-74 I 2-03 12-69 o-74 P 432 Thew 71-1 13-45 54'2 35-6i 12-52 2-84 I 2-00 12-50 o-68 • • « « • • 71-1 13-45 54-2 35-6i 12-52 2-84 : 1 2-00 12-50 o-68 430 Rymer . * « 70-4 13-51 53-2 29-88 10-63 2-81 : 1-96 12-25 o-6i I 1-96 12-25 o-6i 429 Marquis • 11 72’4 13-54 56-2 30-65 n-44 2-68 1-84 11-44 0-69 I 1-84 n-44 0-69 P 466 Brown John Southland Winton, 70-0 13-86 53'2 31-76 n-53 2-76 x-8i 11-31 o-66 I i-8i 11-31 o-66 P 260 Dreadnought . Waitaki. 75-o 12-77 51-0 33-82 8 2-97 1-67 10-41 o-57 I I -67 10-41 o-57 P 259 Kia Ora, Waitaki 73’1 13-10 49’8 35’60 12-00 2-97 I i-75 10-94 0-64 Kia Ora, Waitaki 73’1 13-10 49-8 35-6o 12-00 2-97 : 1 i-75 10-94 0-64 >>

TABLE II.- TESTS FOR STRENGTH OR QUALITY OF FLOUR OF NEW-ZEALAND-GROWN WHEATS (SELECTED RESULTS).