Sugars in the Canning of Fruits And Vegetables P. W. ALSTON
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Spreckels Sugar Co., 2 Pine St., San Francisco, Calif.
For many years only cane sugar was considered as the essential sugar for canning. Improved methods of beet sugar refining made beet sugar as satisfactory as cane sugar. During the second quarter of this century starch conversion products be-came an economic factor in the canning of fruits and vegetables. Sugar and starch conversion products have different physical and physiological properties and cannot be indiscriminately sub-stituted one for the other. It appears that there is much need for sound research to determine the proper medium for each product on a basis of quality as well as of economics.
F e w developments d u r i n g the past century have added more to the increase i n the standard of l i v i n g than the contribution of the a r t and science of canning. C a n ning may be defined as the method of food preserving i n a permanently sealed container. The invention of the canning process by Nicholas A p p e r t and the extraction of sugar from the beet by Delessert, both i n France d u r i n g the Napoleonic W a r s , were the results of food shortages caused by blockade. I n the early descriptions of methods of preservation of f r u i t s , water alone was used to complete the filling of the container—usually a bottle. The h i g h price of sugar prompted the offering of awards for alternative methods of food preservation. F i v e guineas were voted to Thomas Saddington for a cheap method of preserving f r u i t without sugar for use as sea stores. H e advised the consumer to use p a r t of the first liquor poured off for flavoring pastry and to cook the remainder of the pack w i t h a little sugar. Increase i n sugar production soon brought the price down where the sugar could be added d u r i n g the canning process. I n 1810 sugar sold i n London for 60 shillings per pound. A skilled artisan, such as a carpenter, received 30 shillings per week. Today, a week's work would buy 1200 pounds of sugar. Sucrose was the only suitable sugar available u n t i l the second quarter of the present century. I n the first quarter of the century much time and temperature, which are both essential i n their proper usage, were wasted i n a controversy over the relative merits of beet and cane sugar as preserving media. This conflict died down w i t h the development of the present methods of processing beets to granulated sugar. Today practically a l l canners i n the West use both cane and beet sugars without distinction of quality differences. J u s t as W o r l d W a r I I resulted i n a new alignment of opposing political forces, the beet and cane sugar i n dustries and the corn products industry now confront each other i n a polemic discussion of the relative merits of the several media used i n canning. Reading the literature on the subject of the preferred media leaves one as confused on the problem as he is likely to be after the campaign speeches i n a national election. The chief impression to be obtained f r o m such literature is that scientific conclusions are not the objective of much of the experimentation reported; rather the presentations are offered for purposes of propaganda. Joselyn (1), reporting on the influence of the several media on flavor, texture, and color i n the frozen food industry, states that there is too little technological i n formation on the basis of which proper selection of sugar can be made. This remark 75
In USE OF SUGARS AND OTHER CARBOHYDRATES IN THE FOOD INDUSTRY; Advances in Chemistry; American Chemical Society: Washington, DC, 1955.
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can be made w i t h greater emphasis i n regard to the older a r t of canning. The newer industry of quick-freezing required intensive work i n order to produce an acceptable product that could compete w i t h the canned goods. However, the older industry has not deemed i t necessary to determine so precisely the effect of the several materials on the quality of the finished product. Economics has apparently been the principal stimulus to the use of mixtures of various sugar, so much so that the most voluminous information available is i n the form of polemic argumentation before the federal agency concerned with what is printed on a label. It would appear to any conscientious investigator of the question of sugars i n canning that there is no one answer to a l l the packs. The fact that a pure sucrose sirup is best for one p a r t i c u l a r f r u i t does not indicate that i t is the best for a l l . There is such a wide variety of original materials and a divergence of properties of packing media that i t must be an axiom that concerted, concentrated, and honest research is necessary to develop the optimum for each p a r t i c u l a r case. The h i g h income of the A m e r i c a n customer makes h i m quality conscious. A n indication of the type of concerted research desired may be gathered f r o m the few scattered reports available. The stability of certain pigments is affected by lévulose and f u r f u r a l . M i x t u r e s of sugar are preferred for mild-flavored f r u i t s to maintain a desired density without excessive sweetness which tends to mask the delicate flavor. I n canned vegetables sugars are not desired as sweeteners, but are used i n low concentration as a seasoner. Industrial Uses
The industrial usage of sugars as sweeteners has increased twofold i n the past 15 years, d u r i n g which time the population has increased by 1 9 % . This represents an increase i n income and also a decrease i n home preparation. T h i s tendency is expected to grow w i t h increase i n income and population, which w i l l ensure i n creased demand but w i l l also cause more careful selection on the basis of quality. It seems that the problem here is not one of preference of one medium over the other, but what is the most suitable for each p a r t i c u l a r article of commerce. A n increase i n quality w i l l result i n an increase i n demand, which, i n t u r n , w i l l benefit a l l parties concerned. The present trend here i n the West has been to all-liquid media. Beet and cane refiners supply liquid sugars to the canners as l i q u i d - s u g a r of the sucrose type. Starch conversion products i n liquid f o r m are supplied as corn sirup unmixed, high conversion corn sirup, and enzyme conversion corn sirup. The adoption of the liquid media i n canning has been of immense economic advantage to the canning industry i n C a l i f o r n i a . F o r the canning of certain types of nonacid f r u i t s and vegetables the canning medium must be low i n acid-forming thermophilic bacteria. Specifications issued by the N a t i o n a l Canners' Association (2) are easily met by the competent producers of either medium. S u l f u r dioxide is undesirable i f the concentration is above a few parts per million. The delicate color of the f r u i t is impaired and i n some cases the metal of the can is corroded. Direct consumption cane sugars produced by the sulfitation process are usually undesirable for canning but the supply is limited to one section of the country. S u l f u r dioxide is used i n processing beet sugars but not as a bleach as was the practice earlier i n the industry. It is now recognized that a few parts per million of sulfur dioxide added before the evaporation of the t h i n juice act as an inhibitor to the nonenzymatic browning and result i n a sugar w i t h less than 1 p.p.m. of sulfur. I n the same manner the starch-conversion producers have been able to eliminate the objectionable hydroxymethyl f u r f u r a l , an undesirable side reaction product i n starch conversion. Artificial Sweeteners
Some special dietetic packs are prepared w i t h artificial sweeteners. Saccharin, benzoylsulfonic imide has been used since the eighties of the last century. More recently a new nonnutritive substance, sucaryl, the sodium salt of cyclohexanesulfonic acid, has been produced i n two f o r m s — S u c a r y l sodium and S u c a r y l c a l cium. The calcium type is proposed for those whose ordinary salt ration should In USE OF SUGARS AND OTHER CARBOHYDRATES IN THE FOOD INDUSTRY; Advances in Chemistry; American Chemical Society: Washington, DC, 1955.
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be limited. The Food and D r u g A d m i n i s t r a t i o n treats these compounds i n the manner prescribed for saccharin. Two other artificial sweeteners, dulcin (sucrol) and P-400, are classed as poisonous substances and are forbidden for use i n food preparation. Literature Cited
(1) J o s l y n , Μ. Α., et al., Food Technol., 3, 8-14 (1949). (2) Owen, W . L . , "The Microbiology of Sugars, Syrups, and Molasses," p. 156, Minneapolis, M i n n . , Burgess Publishing Co., 1949. 1953.
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RECEIVED September 3,
In USE OF SUGARS AND OTHER CARBOHYDRATES IN THE FOOD INDUSTRY; Advances in Chemistry; American Chemical Society: Washington, DC, 1955.
