AGAR-AGAR a sticky business

Korero (AEWS), Volume 2, Issue 22, 6 November 1944, Page 9

AGAR-AGAR a sticky business

A KORERO Report

Agar-agar — agar for short —is a vegetable gelatine. This fact may not appear either interesting or spectacular, but the story of its development in New Zealand is typical of the way science has come to the aid of industry to defeat what might have been a paralysing shortage. You may have seen on a packet of jelly crystals the warning, “ dissolve in hot, but NOT BOILING, water.” Jelly crystals are made from animal gelatine, extracted from certain slaughterhouse refuse, and animal gelatine cannot be guaranteed to set, or “ gel,” after it has been boiled. However, in canning meat the contents are put into the tin at boiling heat and under pressure in order to ensure that all germs have been destroyed, and where gelatine is required it must be able to stand up to this temperature without losing efficiency. Have you ever noticed the translucent jelly that surrounds the contents in a tin of canned tongues ? This is agar, put in at boiling temperature, and setting as the contents cool. Incidentally, ordinary gelatine would not remain set under tropical conditions, and a tin of tongues would become a cold stew. There is another use for agar, one even less generally known, but nevertheless one of great importance. When a bacteriologist is on the track of the germ that causes a disease, he must have some way of growing colonies of these

germs in order to study their habits. These colonies of germs are called cultures, and since they are hardly the sort of pets one can keep in the back yard, they must be grown in some suitable medium. Gelatine is ideal for this purpose, being translucent and practically colourless, as well as providing food for the growing germs. But, before growing the cultures, the bacteriologist must make sure that there are no stray germs already in the medium — other words, he must sterilize the gelatine, which is most easily done by boiling it under pressure. For this reason culture media are generally prepared from agar. The vaccine on which the health of armies may depend owes its preparation to agar, as do certain sera for innoculations. So far, so good, but here arises the difficulty. Before the war, practically all our agar came from Japan and was, moreover, a costly substance. With the outbreak of . war, importation of agar naturally ceased, and there appeared to be no other sources readily available. At this stage a representative of the meat-canning industry suggested to one of the universities that possibly one of its students interested in research might care to look into the agar problem. However, when the university came to consider the problem it realized that some of the world’s leading chemists were working on it, and that many of its secrets were still mysteries, and the

problem was hardly a fair assignment for a student. They therefore passed the problem on to the Department of Scientific and Industrial Research. The Department remembered that the Japanese obtained their agar from seaweed, and passed the problem on to its Botany Division. The Botany Division, armed with an illustrated text-book on seaweeds (technically known as algae), went out and collected some seaweed.

Now, a ma tai always looks like a matai, and once you have seen a totara you can be fairly sure of identifying any other you meet, and so with most of the denizens of the plant

world ; but seaweeds vary according to the depth at which they grow, the temperature of the water, the type of bottom, and currents and surges, and so on, so that three or four specimens of the same species of weed may be so different in appearance as to appear like different species. Our botanist therefore collected specimens of everything that resembled at all the ones marked in the book, took them back, and tried them

out in test-tubes. _ It was found that , . r the most satisfactory

algae belonged to the family Gelidiaceae, and that of this family the most suitable one was called Pterocladia lucida. Unfortunately, few seaweeds have common names, so it is difficult to avoid the scientific terminology. Pterocladia lucida is a pinkish or reddish fern-like seaweed, quite common in coastal waters round the North Island, particularly, up the East Coast, and in the Bay of Plenty. Finding out just where the weed grew in suitable quantities was, incidentally, a problem in itself.

At this stage a chemist from one of the meat-canneries asked why, since the extraction of agar required no special machinery or chemicals that would have to be imported, some one did not try it out. With this piece of encouragement the Department obtained half a ton of weed and set to work to try an experimental batch. For this purpose the children of Native schools in the Bay of Plenty were recruited, and with the co-operation of the school-teachers sufficient weed was soon obtained, hung to dry on the school fences, and forwarded to the Department.

The results were most encouraging, and the problem then became one of collecting the material on a commercial scale and of finding a firm to undertake the manufacture. A certain amount of negotiation about prices, a small adver- • tising campaign, and the weed began to come in. Native schools again helped, and the fact that the children invariably sent in the right weed showed the feasibility of the scheme. Then School Committees and parents began to realize that the additional -£5 or Z lO added to

the school funds came from seaweed, and gradually the idea of money from seaweed spread. The coastal Maoris in particular were enthusiastic ; a day’s picnic by the beach, unlimited swimming and skylarking in the water, and finally a cheque. Kapai ! The local storekeepers saw money coming into their districts, and assisted ; school-teachers co-operated. The School Journal lent itself to propaganda, and the weed began to roll in. Some of it came in sacks, some was pressed into wool-bales, some had been pressed and baled in hay-balers,

but there was very little rubbish or foreign matter among it, and very few people had sent in the wrong weed. Meanwhile preparation was going ahead for the extraction of agar. The process is a simple one ; briefly it comprises boiling the weed until a “ soup ” is obtained, filtering off the liquid, and then freezing it, when the agar separates out. Here the business proved really sticky; on one occasion the agar “ gelled ” or set unexpectedly, and the experimenters found their equipment neatly set in gelatine. Ultimately, however, all difficulties were overcome and agar came on to the local market in sufficient quantities to meet New Zealand’s needs. There followed further investigation of Pterocladia lucida to see whether it would regenerate fast enough to keep up the supplies, or whether picking would have to be regulated. It appears, however, that, picked by the methods now in use, there will be ample weed for New Zealand requirements over an indefinite period. The possibility of other weeds being used has not been overlooked, and

research is still proceeding, but so far no better source than Pterocladia has been found. Up till April, 1944, over 120 tons of the dry weed had been received, the Internal Marketing Division acting as purchasing agent, and of this

weight about one-quarter was agar. Since then the industry has grown steadily. What of the quality of our agar ? Tests carried out by the Imperial Chemical Institute, South Kensington, reveal that it closely resembled Saghalien strip (a Japanese product) and gave a gel strength at least twice as strong as that of the best Japanese. As a result, manufacturers are able to use solutions of as low a strength as o-6 per cent, to give a gel strength equal to i per cent. Japanese solution. Biologists report also that the agar now being supplied is excellent for the growth of bacteria and fungi, giving results equal to that given by the best Japanese agar. This, then, is the story of a combination of science and industry to overcome an urgent problem. Now that the industry has been started, it is unlikely that Japan will ever regain the market which she held for so long, which is to say that so much more money will circulate in New Zealand. One minor incident of the research adds piquancy to the story. By a small wharf in a northern town was a meatcannery, and over that wharf hundreds of pounds worth of expensive Japanese agar had been landed. Underneath the wharf was growing our friend Pterocladia lucida— agar on tap.

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