发酵食品的未来(英文版)

FUTURE OF FERMENTED FOODS C. W. HESSELTINE* OJ Official Ue.~ 4852 Future of Fermented Foodst C. W. Hesseltine* Foods prepared by fermentation, aside from those well known in the West, will increas~ in amount and use ~nd will.spread to other parts of the world, including the western developed countries. The author discusses the factors influencing the greater use of traditional fermented foods. Introduction A look at where fermented foods are going in the next few years seems to be an appro- priate exercise. One can speculate wildly about the future and, at the time of writing, no one can fault the opinions given. The author's only qualification to look into the future is that the Northern Regional Research Center has been involved in sporadic research from the late 1940's to the late 1950's, at which time research on a small, but continuous, scale was initiated; it is still continuing today. Besides the author's work, people from various countries (Brazil, Thailand, Indonesia, and Japan) have worked on programs in this laboratory. PL 480 funds have supported projects in Israel, India, Taiwan, and Japan on fer- mented soybean foods. These contacts have done much to give us cultural, econo- mic, and scientific information and under- standing about foods produced by fer- mentation. In this paper fermented foods exclude alcoholic beverages and well-developed Western foods such as bread, cheese, sausage, sauerkraut, yogurt and pickles. Rather, the fermented foods dealt with here were not produced in the West until recently, or are still unknown outside the native area in which they have been pro- duced for centuries, many going back even before recorded history. In making a projection on fermented foods, a number of conditions are having a positive effect while there are others having a negative one. At least six positive factors suggest a greater role for traditional fer- mented foods: 1. All food preparation requires various inputs of energy. Energy costs have increased dramatically, and there IS no indication that cost ever will be reduced. These costs affect people of less wealthy countries tPresented at the Vlth International Fermentation Symposium. London. Ontario. Canada. July 20-25. 1980. 2 The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned. -The author's address is Northern Regional Research Center, Agricultural Research, Science and Education Administration. U.S. Department of Agriculture,2 Peoria. Illinois 61604. even more than those of the prosperous countries. Energy is required in four differ- ent phases of food production; namely, the amount used for agronomic activities (ploughing, seeding, cultivation, harvesting, etc.); transportation to market from the farm and from the factory to the consumer; preservation (chemical preservatives, drying, canning, and refrigeration); and processing (physical and chemical modification and packaging). Each step requires energy. Because energy is recognized worldwide as a critical economic and political issue, there is a mounting interest in ways of reducing its use in all processes, including the produc- tion of food. 2. Because of the increasing world popula- tion, the food supply now has become critical and will be even more so in the future without worldwide control of the birth rate or the decimating factor of war. This suggests that one of the strategies in the future must be to produce more food and to do a better job of saving it from decay, insects and rodents. The world's crop losses from disease represent 11.1 % of the soybean crop and 9.4% of the corn crop, and may go as high as 23% of the banana crop. I 3. Besides considering the energy input, the pollution that usually accompanies processing must also be considered. The added pollution results in either the use of money to control the problem or the deterioration of the environment and its consequent adverse effects on man, directly or indirectly. In addition, much food is lost in the processing. For example, in modern and Western society more and more wood products are being used for packaging of food and nonfood products. As a result, of the increased production, more wood sugars are being dumped in streams; these sugars could be fermented away with the addition of a cheap nitrogen source to make single cell protein. To a small extent, this product is now made from paper manufacturing wastes which is used in human foods as a source of protein and vitamins. 4. Losses due to spoilage by bacteria, yeasts, and fungi have increased as the distances and time required to transport the product have increased between the farmer and the consumer. Ripe tomatoes grown in the Peoria area can be harvested and sold directly to the consumer, resulting in very little loss due to microbial spoilage; but tomatoes grown in Mexico and shipped to New York offer a different problem. The trend in the last few years has been to concentrate production of crops in certain areas which, in turn, supply the whole country. This applies to field crops as well as vegetables and fruit. Likewise, because of labour costs, there is a strong trend towards more meChanical harvesting and handling at a higher moisture content (as in the harvesting of corn) with more mech- anical damage due to crushing and breaking, all conducive to more microbial spoilage. All organic matter is subject to attack by microorganisms within a proper moisture and temperature range. 5. Tillable land is decreasing throughout the world for the production of food. This suggests that one of the strategies is to bring into use a better utilization of plant and animal products now unfit or not used for human food. A good example is the waste fish such as undesirable parts and small fish' which could be upgraded by fermenta- tion'to make desirable, acceptable, and safe. foods high in protein and acceptability. Although this process currently is being used to contribute to the food economy, still the process is greatly under utilized. 6. Food habits are slowly turning towards more foods of vegetable origin, partly because of food costs and partly due to a belief, at least in the West, that a bulky, low-meat diet is beneficial to the consumer. Some are advocating that foods with less processing are more healthy because of increased fibre, less food additives, and a higher vitamin content. This latter feeling is- a controversial matter; nevertheless, it does affect th~ food habits of a great number of people. Opposed to the positive forces encourag- ing increase in production of fermented foods, the following six are negative factors. (1) In any microbial process there will be a loss in the starting material for the simple reason that energy is required for growth of the microorganism. In vigorous fermenta- tions, such as tempeh making, the 'Ioss is appreciable even though the fermentation lasts only 'a matter of hours. (2) Fermenta: Table 1. Annual production and import of soybean in Korea Table 3. Amounts of soybeans used in Indonesian fermentations Table 2. Consumption pattern of soybean foods in Korea about 75,000 tons of soybeans as com- pared to 41,000 tons for tofu. 3,4 The daily consumption of tempeh is from 30-120 g per capita.4 Tempeh is becoming an impor- tant food in Malaysia. Table 3 shows the amounts of soybeans used in Indonesian fermentations.4 268,285 282,875 255,407 318,786 384,946 371,555 442.803 Total (MIT) 36,291 60,573 31,468 72,964 66,370 61,000 147,854 Import (MIT) 83,845 tons of soybeans are used in Indonesia, with a U.S. dollar value of 39 million. 5 Tempeh is produced in 41,200 shops by 128,391 workers, with the largest factory producing 422 tons per year. This tempeh is sold at about $).23 per pound on the retail market. Japan Shoyu has been produced in Japan for 1500 years: The annual production of shoyu in this country is about 120,000,000 kilolitres per year; this figure has remained almost unchanged since 1974. With 3600 shoyu producers in Japan, five companies account for half of the total production. Consumption per capita averages 12 litres per year; of this 63% is consumed in the home and 37% is used in food industries and restaurants. Daily consumption of about 34.1 g per day contributes 14.0 calories, 2.4 g protein, 0.2 g fat, and 5.8 g salt to the diet. Natto is of two kinds: hamanatto which resembles miso in taste, and itohikinatto, made with Bacillus natto 7 • The 100,000 metric tons produced in 1970 has increased to 158,000 in 1979. The total production of fermented soybean foods have gone from 932,000 24.5% 10.6% 18.3% 6.6% 28.5% 9.0% 0.14% 2.4% 16.1 0.371 0.882 8.8 Tons Value Rp in billions 75,600 501 415 41,405 231,994 222,302 223,939 245,822 318,576 310,555 294,949 Production (MIT)Year 1970 1971 1972 1973 1974 1975 1976 Tempeh Kecap Tauco (like miso) Tofu (not fermented) Curd (tofu) Shoyu (soy sauce) Paste (miso) Hot soy paste Oil and defatted meal Sprouts Milk Other tions require some knowledge of micro- biology, or at least some specialiZed training with the microorganisms one is using.. Without some knowledge of microbiology, disaster is just around the corner. For example, copra is sometimes used as an adulterant in making tempeh; however, if the fermentation becomes contaminated with Pseudomonas cocovenenans, illness and death occur due to a poison that affects the central nervous system. (3) Because all fer- mentations can be considered as controlled spoilage of the substrate, there are some hazards from bacterial and mold toxins. In koji-making, strains of Aspergillus oryzae are used to make enzymes. But, a closely related species, A. flavus, which has the same growth appearance and growth require- ments, will produce varying amounts of aflatoxin. When selected strains of A. oryzae are obtained from reputable culture collec- tions supervised by expert mycologists, no problem occurs. (4) Various fermented food products have special inherent dis- advantages due to their characteristics. For example, shoyu and miso have a high salt content that allows the product to be kept for long periods of time without refrigeration. However, this high salt con- tent limits the amount of product that can be consumed at a meal. Fresh tempeh cakes, on the other hand, must be consumed within 1 or 2 days or the mold proteolytic enzymes will cause ammonia to form, which results in an undesirable taste. (5) It is obvious that even the simpler fermenta- tion processes involve added costs because of the extra handling, labour, and fermen- tation equipment. (6) Some people find products made by fermentation objection- able. Western people in general reject any product made with molds. The only mold products they are acquainted with are certain cheeses in which Penicillium is used, and even these familiar products are. rejected by some. Trends in production of fermented foods In looking at the future of traditional fer- mented foods, it is instructive to see what has happened in the past few years to some of these products, both in the United States and abroad. Unfortunately, the actual amounts of materials consumed usually are not known, and some of the data may be questionable. Data will be presented by country rather than by food product, because the foods are different from one country to another. Korea Fermented soybean products (paste and soy sauce) go back at least to 634 A.D! In 1976, the consumption of soybeans per capita was 12 kg. The annual production and import of soybeans has been going up as shown in Table 1 (taken from the above reference). The breakdown of the use of these soybeans is shown in Table 2 (adapted from Fig. 12 ). Thus, about 35% of the 442,803 metric tons of soybeans is fermented. Indonesia In Indonesia the tempeh industry uses Table 4. Utilization of soybeans and soybean meal in fermented foods and tofu in Japan4 Category 1973 1974 1975 1976 1977 1978 (1,000 metric tons) Frozen & dehydrated tofu United States 28 24 28 26 28 29 Chinese 5 9 7 3 0 1 Total: 33 33 35 29 28 30 Shoyu On terms of beans) United States 249 240 231 230 240 251 U.S. beans 16 14 11 10 8.5 6 Natto United States 3.7 3.7 3.0 40 45 46 Chinese 66.1 72.7 71.0 24 15 15 Japanese, domestic 3.7 4.1 4.0 5 10 10 Total: 73.5 80.5 78.0 69 70 71 Miso United States 38 27 16 98 130 11 Chinese (PRC) 132 132 169 80 40 129 Canada 1.5 2 5 5 Japanese, domestic 17 17 12 10.5 10 40 Total: 187 176 198.5 190.5 185 185 Tofu and aburage United States 379 371 357 383 402 420.5 Chinese (PRC) 20 20 20 10 5 5 Brazil 1 2.5 2 1.5 Canada 5 6 8 10 Japanese, domestic 10 11 10 10 10 8 Total: 409 402 393 411.5 427 445 Table 5. Production of kaffir beer by industrial fermentation" in South Africa Table 6. Consumption of fermented shoyu in the United States and Japan Bulk Pack beer Total Year millions of millions of millions of Total value litres Iitres lit res (million rand) 1974 425 518 943 68 197'5 409 504 913 76 1976 342 501 843 82 1977 348 531 879 90 "Home production may be nearly as much! metric tons of soybeans in 1971 to 946,000 tons in 1976.8 It is instructive in determining the status of fermented food to see the amounts of soybeans being used over the last few years in Japan for fermented foods. These data are shown in Table 4. It is apparent from Table 4 that total usage for tofu has increased somewhat but that other products have stayed con- stant. The country of origin for soybeans in the various fermentations is not the same. For example, until recently the Japanese bought mostly Chinese soybeans for miso making, whereas almost all the shoyu is made from U.S. soybean meal. Year Gallons of liquid shoyu car:sumed Pounds of shoyu solids consumed United States" Japan United States" Japan South Africa One of the fermented food products in South Africa for which production figures are available is kaffir beer. This is a native beer that is consumed more as a nutritious food than as a drink for pleasure. Data on this fermentation over a period of 4 years are shown in Table 5. 1974 2,600,000 311,676,000 1975 2,900,000 293,331,000 1976 3,300,000 320,728,000 Annual per capita consumption in: Japan 12,000 ml U.S. 57 ml "Domestic production plus imports from the Orient. Table 7. Tofu shops and soy dairies in the West" 8,840,000 9,860,000 11,220,000 1,059,698,000 997,325,000 1,090,475,000 the West, it now appears that several foods (shoyu and tofu) are becoming known and being accepted by non-Oriental people, especially among those interested in vege- tarian diets. The reasons for no growth or decline in consumption of fermented foods in some countries is not known. One can surmise that several factors, acting together, could bring this about. As incomes increase, there is a trend towards replacement of vegetable protein by red meat, dairy prpducts, and poultry. Added to this, perhaps, is the inability of the manufacturers to change and adopt to the younger generation's changing food habits. The more progressive companies are beginning to adjust in various ways. Some miso companies are now developing a low-salt miso and suggesting ways of using miso in sauces for Italian types of food now popular in Japan. Another factor that may be working against traditional fermented foods is the desire to eat new foods brought in from the West. For example, beer sales in Japan have adversely affected the sale of their tradi- tional drink, sake. There now follows a look at what the future may hold for fermented foods, aside from those well known in the West. An increase in consumption of these tradi- tional foods in countries where these foods were not formerly produced may be expected and a spreading of fermented products to other parts of the world. They will undergo modification in taste and appearance and, in some instances, will be used in other ways than the ·traditional ones. It is hardly expected that soybean paste will ever be used as a base for a hot breakfast food in the West, but it is likely to find use as a flavouring agent in sauces, salad dressings and spreads. On the other hand, tempeh will probably be sold as a protein food, just as it is used in the East Indies. Shoyu is already sold widely in the West as a modified sauce, such as teriyaki sauce for use in barbecuing poultry and meat. There are a number of factors that may have an effect on the wider use of fermented foods in the West and in coun- tries where those foods already are known. 1. Prevention ot food poisoning. The fer- mentation of a commodity often will result in a product that is protected from food- poisoning microorganisms that grow and produce toxins. Typical food poisonings are caused by the botulinal toxins, which cause a number of deaths each year in the United States (114 cases reported in 1977), and the enterotoxins, which although not fatal, cause acute illness. The conditions during fermenting that prevent the growth of such toxins are the low pHs encountered due to the growth of lactic acid bacteria, the high salt content, and the presence of antimicro- bial' agents. The use of fermentation is such an effective method that it is still used in the highly developed countries for proces- sing cabbage, olives and cucumbers. These methods are still used because the fermenta- tions (1) yield certain desired organoleptic qualities, (2) provide a means for extending the processing season, and (3) require little mechanical energy input.'o The Food and Drug Administration has found no reported illness due to botulism in commercially processed fermented foods in the United States. Canada, the United Kingdom, and Japan.'o Besides the rapid lowering of the pH, lactic acid bacteria produce compounds that are antagonistic to spoilage bacteria. Clostridium botulinum growth is prevented United States The four products to be considered here are shoyu, tempeh, miso, and a traditional but nonfermented product, tofu. However, in the Orient, tofu is sometimes fermented to make sufu, a fermented soybean cheese product. Data has been presented (shown in Table 6) on shoyu consumption in the U.S. as compared to consumption in Japan. 6 U.S. consumption is increasing rapidly but is less than 1/200th of that in Japan. Tofu (precipitated soybean milk) is growing rapidly in popularity in the United States among the non-Oriental population. Table 7 shows the increase in number of tofu shops and soy dairies in North America and in other Western countries (Europe, Australia, and South Americal. The number of tofu shops in the United States run by non-Orientals rose from zero in 1975 to 96 in just 4 years. According to Richard Leviton, editor of the journal Soycraft, the estimated retail value of tofu in the United States is $33,750,000, repre- senting sales of 188 companies which employ 680, people. Today, tofu can be purchased in many supermarkets and usually is displayed in the fruit and vege- table section. The number of shops selling Tempeh (an Indonesian fermented soybeans product) has risen from a total of 22 shops in 1978 to, 29 in November 1979. Unfor- tunately, no data on the amount of miso imported or made in the United States could be obtained. It is reported that one company makes about 500 tons of miso yearly in the United States. From this admittedly sketchy and incomplete data on the use of fermented foods, it appears that in those countries where production figures are available- and where fermented foods have been made for centuries, the amount produced is staying approximately constant. For the less deve- loped countries, there is no data on the consumption of fermented foods and no one can even make an estimate, but it is probably surprisingly high. HO"Yever, in Year 1975 1978 1979 North American Caucasian o 63 96 Oriental 53 51 68 Other West 2 10 36 Total 55 124 200 at a pH of 4.6 or b