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Food-science

The role of tofu processing in development and the alleviation of malnutrition in West Java
Studies on reduction in viscosity of thick rice gruels with small quantities of an amylase-rich cereal malt

The role of tofu processing in development and the alleviation of malnutrition in West Java

Fransiska Zakaria and Tien Ruspriatin Muchtadi
Food Technology and Development Centre (FTDC), Agricultural University, Bogor, Indonesia

INTRODUCTION

Malnutrition is a serious problem in developing countries. In Indonesia, it is most severe among the rural population. Nutrition-oriented agriculture and food processing—that is, choosing certain agricultural commodities and processing them into acceptable foods—are important in combating malnutrition, and the choice of commodity becomes more significant if it is economically sound and socially acceptable.

Indonesia, with its current population of 150 million, is estimated to consume 130 kg of rice per capita per year. Rice alone is nutritionally incomplete, so it is necessary to combine it with other inexpensive agricultural products to make up a balanced diet. Meat, eggs, and milk are well known for their superior nutritive value; however, for most people they are far too expensive. Since to change the rice-eating pattern would require enormous efforts, it should instead be taken advantage of, and soybeans provide a perfect nutritional match for rice.

Among the many soybean products, tofu (soybean curd) and tempo (fermented soybean) are the most popular and inexpensive protein sources. It is not surprising that although Indonesian scientists continue to explore protein sources for the future (algae, single-cell protein, and others) to meet the increased demand, most experts still consider soybean and its various products to be the most realistic and promising source of low-cost, high-quality protein available in large enough quantities.

The industry that produces tofu is usually characterized by its small scale, simple technology, and orientation toward consumers. Gainful employment for thousands of rural people and a substantial amount of locally generated income could be produced by this industry.

Foods are consumed for a variety of reasons, and nutrition may not always be one. In Indonesia, where most persons have a low income, buying capability, coupled with food habits, plays a major role in what a family eats. In West Java, as is common in Indonesia, people first buy rice as their staple food. If they have money left, they then buy other foods. Those that are generally chosen, in order of price from the cheapest to the most costly, are salted fish, tofu and fermented soybean products such as tempe and oncom, vegetables, fresh fish and other seafoods, poultry, milk and milk products, and meat and meat products. When people have a higher income and are more able to meet their basic needs, food preferences and nutritional value become more important, and usually they have a wider range of food choices.

Food consumption is also related to tradition, social factors, and religion. Fortunately, soy-based products such as tofu and tempe are frequently eaten by the people of West Java and Indonesia in general, especially the at-risk population.

Since tofu is a well-accepted dish and an excellent inexpensive source of protein as well as other nutrients, and because its processing requires only simple technology, expanding tofu production will not only improve the nutritive value of the low-income population's diet but will ensure a chain of productivity involving farming, processing, and marketing among the rural population. Furthermore, the tropical climate of Indonesia is suitable for soybean cultivation.

One aim of this research was to find information on how much tofu is really consumed by the at-risk population in West Java, how important tofu is compared to other dishes, and how available it is. The other aim was to investigate the prospect of expanding tofu shops and the economic growth that would result. We then reflected on the degree to which the processing of tofu in West Java constitutes a means of supplying nutritious food to the at-risk population and of generating employment for the poor in the surrounding area, while making use of the soybean crop produced by farmers.

Muto et al. [10] tested tofu as a source of protein in the solid diet of weanling infants and evaluated its performance with respect to acceptability, weight gain, nitrogen balance, and serum protein level. Based on these criteria, it was judged that tofu was nutritionally equivalent to the protein derived from a mixture of eggs, fish, and liver. Furthermore, although soybean protein is deficient in methionine and cystine, the fact that it has a much higher content of lysine (6.7 g per 16 g N) [13] than most cereal proteins contributes much to its protein value in cereal-based diets. Thus, the proteins of rice and soybean are complementary and the mixture has an excellent protein valve.

FIG. 1. Basic tofu processing

However, the quality of a mixed protein does not always show a linear relationship with the increased amount of complementary protein in the mixture [3] . A diet containing 8 per cent soy flour plus an additional 4 g protein by supplement consists of 43 per cent soy protein and 57 per cent rice protein and is considered of optimal nutritional value [5].

Tofu is a traditional, natural soybean product prepared in essentially the same way today as it has always been. After the whey has been ladled off, the soybean curd is left to curdle in barrels (fig. 1). As these processes do not require high technology, tofu can be made at home.

Tofu has a relatively short shelf life. At room temperature, without any method of preservation, it will spoil within 24 hours. Tofu producers utilize simple methods of preservation to prolong the shelf life, such as boiling to reduce the number of contaminating micro-organisms. Turmeric extract is one of the preservative agents, and at the same time gives the tofu an attractive yellow colour.

For marketing, tofu is usually kept in water to protect it from direct contact with air micro-organisms. Keeping it in a cold room also lengthens its shelf life.

The economic value of tofu shops was recently discussed in a national newspaper. In Sumedang, a town in the eastern part of West Java well-known as a tofu town, there are currently about 150 tofu shops that use almost 10 tons of soybean daily. Half of the amount is imported, while the rest is grown locally. The national soybean production for 1983 to 1984 was estimated to be 974,000 tons.

The shops are reported to employ more than 1,500 labourers in addition to generating lucrative by-products such as soymilk cakes for making oncom, a fermented food product. During the last decade, these shops have been replacing the traditional stone mills with simple electric mills, a change that has multiplied the production intensity ten times and the capacity three times.

RESEARCH METHODS

Marketed Tofu

To obtain reference weights and prices, the correlation of each price category and average weight of tofu sold in the community was observed. Samples were purchased from two markets in Bogor in each county and tofu vendors in several villages. Tofus of each price category were weighed and the protein content was determined using the micro Kjeldhal method. The calculated average weight of each price category was used as a reference weight.

The investigation was carried out by interviewing groups of families that were classified according to monthly income:

Group I: Less than $40.00.
Group II: Between $40.00 and $100.00.
Group III: Between $100.00 and $200.00.
Group IV: Between $200.00 and $300.00
Group V: Between $300.00 and $400.00.

Surveys were conducted in Ciomas and Semplak counties in West Java. From each village, at least five families were chosen to represent groups I and II. To obtain families to represent groups III, IV, and V, surveys were conducted in Bogor and among persons living in university housing.

The interviews covered parents' occupation, nutritional attitude, food consumption, tofu preference to salted fish, ability to buy tofu, and family size. Nutritional attitude was scored 1, 2, and 3 for poor, fair, and good respectively. Tofu consumption, expressed in grams per person per day, was measured indirectly after converting the quantity of a certain price of tofu consumed to its weight, using the standard weight previously obtained (table 1). Other food consumption was ascertained directly from the interviews. The amount of tofu a family could buy if they used their discretionary income was also recorded. The results were further used in estimating the amount of tofu that could be supplied in each village by multiplying it by the village population. The latter figures were obtained from the local government office.

Tofu Shops

To project the economic contribution of tofu shops, a survey was carried out among 20 shops in Bogor City. The shops observed were chosen randomly, and interview topics included source, price, and quantity of soybean used, and processing cost including labour and fuel. Production was estimated, based on the yield of the university pilot plant, and was observed in several of the shops visited. The shops were categorized as small-, medium-, and large-scale production and the production characteristics of each category were described.

RESULTS AND DISCUSSIONS

Tofu Locally Available

In Bogor, local tofu markets are scattered throughout the city, although vendors are sometimes the sources for a family. In the villages, where a market does not always exist, the primary suppliers are vendors. Even so, the vendors, who travel on foot carrying the tofu on a simple shoulder-pole, do not come to each village every day.

In the two counties visited, one market is shared by at least five villages. These markets are mostly used daily by those who live within walking distance and occasionally by those who come from farther away to purchase all their daily necessities Tofu sold in these markets and by vendors comes mostly from shops outside Bogor. If tofu is to be made more available in these villages, either shops must be built there or more effective vehicles must be provided to the vendors. The former alternative is discussed in the last part of this article.

TABLE 1. Price, weight, and protein content of tofus taken from local markets and vendors

a. US$1 = Rp 997.
b. Samples taken from local tofu vendors. The rest were from two local markets.
c. Unpressed tofu.

In both city and villages, tofu is bought by pieces that vary in price. In the city markets, it is sold in more diverse sizes, the larger sizes usually being heavier and more expensive. However, some pieces of the same price could have different weights (table 1), because of the non-uniformity of the pressure applied to the soy milk curd before the pieces are cut in the shop. Some shops do not even press their product in order to make "pong" tofu, which is used as a snack. Thus, apart from the size of the pieces, the difference in weight is also a reflection of high water content.

It was necessary to obtain a reference weight for a certain price of tofu in order to calculate the amount consumed, as the respondents are not used to buying it by weight. The reference weight of the various prices, which is the average weight derived from each price category, is presented in table 1.

Amount of Tofu Available in the Villages

The amount of tofu that could be purchased by the village community, except for Bojong village, was higher than the amount consumed. This indicates that even poor families have some discretionary income. It is possible that these families spend as much money on food snacks and drinks as on food for meals.

An increase in the distance from the market and main street did not discourage tofu consumption.

Economic Value of Tofu Protein

The price, size, and hence weight of tofu available in the market do not affect the price of its protein. Thus, a single value of 0.3 or 2.3 cents per gram protein is applicable to all the tofu available.

This represents a large economic advantage of tofu protein over meat protein. At present, the price of meat protein in the two counties' markets observed is 3.5 cents per kg or 9 cents per gram protein, which is close to four times that of tofu protein.

Tofu Consumption

Effect of Income Level

Tofu was consumed by persons of all income levels in increasing amounts parallel to increasing income level.

TABLE 2. The average side-dish consumption (g/person/day) of the five monthly income groups in two counties in West Java

a. Tempe consumption was obtained from 5, 3, 10, 3, and 3 family respondents for income groups I, II, III, IV, and V respectively.

FIG.2. Curve of tofu consumption of the five income groups in West Java

TABLE 3. Tofu and other protein consumption (g/person/day) of the five monthly income groups in West Java

However, when income level reached $300 to $400 per month (group V) the consumption stopped increasing. The highest amount of tofu consumed was 48 g per person per day by group III, income level $100-$200 (table 2 and fig. 2). As the income increased, except for salted fish, the food choices included more meat, eggs, and milk, as was indicated by the corresponding increased consumption of these food items.

This evidence is supported by the amount of tofu the groups could buy. Group I (income level less than $40) had the lowest ability to buy. Almost all of the respondents in this group were able to buy only 50 g or less per person per day, while approximately two-thirds of those in group II (income level $40 to $100) were able to buy up to 100 g if they used their discretionary income. The number of respondents able to buy 100 to 200 g and more was smallest in the lowest two income categories.

Even though persons in income groups III, IV, and V, who lived in the city and/or university housing, were able to buy more than 100 g per person per day, they actually consumed far less 148.0 9). Also, in the eight villages, where all respondents represented income groups I and II, the average additional amount that could be bought was 63.7 9; however, actual consumption was 28.7 g per person per day. It seems that 50 g of tofu per person per day was the maximum consumed. This quantity is only slightly above twice the amount actually consumed in the villages.

Contribution of Tofu Protein to the Total Food Protein Consumption

The quantity of protein consumed by all income groups was calculated from the data in table 2 (see table 3). There was only a slight difference in total side-dish protein consumption for groups I and II. Sharp increases in total protein consumption occurred in groups III and IV, followed by a slight increase in group V. Besides rice protein, tofu, and other soybean products, tempe and salted fish provided most of the protein. In group III tofu made up the greatest quantity of side-dish protein.

As shown in figure 3, the amount of side-dish protein consumed becomes greater as income increases. This is due to the increasing consumption of almost all foods, especially meat, with the exception of the decreasing consumption of salted fish. In the three lower-income groups, tofu protein contributed much to side-dish protein consumption; in group I it constituted 19.6 per cent of total side-dish consumption (table 4). As income increased, the level of tofu protein increased to 27.0 per cent in group III, then decreased to 13.7 and 17.3 per cent in groups IV and V. On the average, tofu protein contributed 21.2 per cent of total side-dish protein consumption and 12.8 per cent of total food consumption.

The average adult rice consumption in the low-income population reported by Guharja and Khumaidi [8] was 333.7 g. Assuming that the average family number of the lowest-income group is six and consists of three children, the average rice consumption of these two groups will be 225 g per person per day. This amount is estimated to contribute 13.5 g rice protein per person per day to the total side-dish protein consumption.

To adapt to the soy-rice protein diet suggested by Elias et al. [5], ideally the percentage of soy protein in the diet should be at least 43 per cent to attain the maximum protein-energy ratio (PER) of 2.88. This percentage is more than three times greater than the actual soy protein (12.8 per cent) consumed in the villages. As previously discussed, the present rural tofu consumption is only one-third of the amount the village could possibly buy; in other words, if the villagers" currency were used maximally, they would be consuming a diet with the mixed soy-protein ratio. Calculating the quantity needed, about 10.2 g of protein or 100 g tofu is required to balance the 13.5 g of rice protein ingested daily to achieve a diet with PER of 2.88.

FIG. 3. Comparison of tofu protein consumption to all side-dish and all food protein consumption

TABLE 4. Tofu protein contribution to the side-dish and all food protein consumption in five monthly income groups in West Java

It is apparent that although tofu protein plays an important role in the population's diet, it is not independent of other food sources in meeting rural protein requirements, especially those of animal sources. Furthermore, even though villagers did not use their full ability to buy, protein requirement was still not met. Also, the contribution of rice protein of 13.5 g reached its peak considering the volume of rice consumed. Care should also be taken, since the increasing amount of soy protein in a mixed soy-rice diet after it reaches its optimum quantity will further reduce the PER value of the mixed protein.

Additional results of this investigation revealed the consumption pattern of the other cheap food protein sources, namely tempe and salted fish (table 2). Tempe is a fermented whole soybean product that has undergone a substantial amount of investigation [14]. This product is consumed in approximately equal amounts to tofu, salted fish, and probably oncom, In contrast to tempe, oncom has received little attention and so its nutritive value is still unknown. It was recently noted by Bressani [4] that the soy cake left after pressing soy puree in tofu production had a higher protein value than soy curd, owing to the higher lysine content. None the less, these products should be given first priority in the battle to overcome the problem of protein malnutrition among the at-risk population in Indonesia.

Preference for Tofu over Salted Fish

Salted fish is an indispensable side-dish accompaniment to rice for the low-income group, and it is therefore neccessary to use this food as a reference. As shown in figure 4, the two low-income groups did not show specific preference for tofu over salted fish. We concluded that for these persons tofu is as acceptable as salted fish.

FIG. 4 Preference for tofu or salted fish in the five income groups

In contrast, only a small portion of group III preferred salted fish to tofu. Group IV liked tofu as much as or more than salted fish, and group V preferred tofu to salted fish. This evidence may also explain the levelling of the tofu consumption pattern as affected by income.

As income increased, tofu was preferred over salted fish. Even in the lowest income group, only about one-third of the respondents preferred salted fish. This contradicted the consumption pattern of this product (see table 3), which was equal to or even higher than tofu consumption. This is probably because the respondents were reluctant to admit their preference for salted fish, which suggests that tofu has a higher social and/or economic standing.

The fact that the greatest amount of tofu was consumed by group IV and that the parents' education in this group varied from illiterate to university level suggested that those with sound education but lower income consumed tofu the most. Moreover, the decreasing amount of tofu consumption in groups IV and V supported our assumption that tofu possesses less social value than the meat, eggs, and milk group. This led to an early conclusion that greater nutritional knowledge about tofu could increase its consumption.

Effect of Family Size

As was discussed previously, families with an estimated monthly income of $200 and above were able to buy at least 200 g of tofu per person per day. This finding was not affected by the family size since increased income seemed to be followed by increased family size.

Family interviews provided evidence that this increased family size did not reflect an increase in offspring, but rather in the number of relatives and in-laws that live in the same house. Almost all of the houses visited in the village were occupied by more than a single family. Still, this type of collective living should not affect the average food intake. The small family size in group V suggests that persons in the higher income group mostly live in the city or in university housing, and either have fewer offspring or are less open to collective living.

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