Dietary fiber is becoming very popular these days. The benefits of dietary fiber to maintain the function of digestive system, stabilizes blood sugar levels, lower cholesterol levels and the risk of cardiovascular disease, even prevent colon cancer are well known by the public. Even BPOM (Indonesian FDA) already allow nutrition and health claims on processed foods containing certain food fibers with a certain degree.
Academy of Nutrition and Dietetics (AND) which is the largest organization for professionals in the field of food and nutrition in the United States recommends people to consume various types of dietary fiber. As is generally known, dietary fiber contained in many plant-based foods such as fruits, vegetables, nuts, tubers and cereals. Some of fiber-rich foods can be consumed directly, but some others must be processed before it can be consumed. Most types of dietary fiber also can be used as supplements and food additives such as thickeners, emulsifiers, stabilizers and bulking agents.
Here is the food processing guidelines for some groups of foodstuffs rich in fiber:
1. Fruits
Fruits are rich in fiber food that can be consumed directly without having to go through the process of cooking or other processing. With direct consumption, the benefits of dietary fiber can be obtained to the maximum, as well as other nutrients. Wash fruit before peeled or processed for sanitary reasons and maintaining its nutritional value. Soaking the fruit with a solution of sulfite (NaHSO3), vitamin C, citric acid, salt and hydrogen peroxide (H2O2) can improve or reduce the occurrence of browning reaction. Soaking in lime water also can improve the texture of the fruit as it can react with dietary fiber pectin contained in the fruit to form calcium pectate. Use a blender or juicer for processing fruits into fruit juice or fruit concentrate commonly done, but of course the dietary fiber content of the fruit will be much less than direct consumption. If you want to process the fruit into a drink, it would be nice if the waste is not disposed of, because there are a lot of fiber in them. Some kinds of fruits such as grapes, apples and pears even have higher fiber in the skin, so better not peel off or discard the skin. If you buy a commercial fruit jam or jelly in the market, choose the one which have texture closer to the original pieces, not too fine in order to maximize the benefits of its fiber.
2. Vegetables
As well as fruit, generally the benefits of vegetables will be maximized if consumed directly. Certain vegetables can be consumed raw in the form of fresh vegetables or salad. Washing vegetables before processing will be better in terms of sanitation and nutritional value. Another way to consume raw vegetables safely is using blanching technique, namely washing by dipping a few minutes in hot water or steam, which is then immediately poured cold water so the heating process does not continue. This method is useful to deactivate enzymes to inhibit browning reactions, decrease the number of microbes, improve palatability, and maintains other nutrients, including dietary fiber. This method is good for cooking on a variety of vegetables such as spinach, broccoli, cabbage, mustard greens, beans, and carrots. Blanching time is determined by the texture of fresh ingredients. Therefore, blanching should be done for each vegetable, not mixed with each other. Vegetables should be blanched in one piece and the cutting is done immediately after the blanching process is complete. If you want further processing, cooking time should be as short as possible in order keep the texture, dietary fiber and other nutrients value. Stir-frying vegetable is one of the good ways of processing vegetables for a relatively short time. Too long cooking time will make the texture of the vegetables are wilted and less crisp when eaten.
3. Tubers
Tubers like yam and cassava have a higher fiber content than rice. In contrast to the vegetables and fruits, tubers cannot be consumed raw. There are several ways of processing the tubers that can maintain the nutritional content of their food, including fiber, such as boiling, steaming, baking and grilling.
– Boiling is a way of cooking that is easy, fast and most safe for health. Rinse the tubers before boiling and select the most appropriate covered pot to the size and shape of the food, to minimize the amount of water used. Boil the water first, before entering the tubers to maintain the color and nutritional value of the food. Use enough waters, because too much water will dissolve more nutrients from foods that are boiled. Among the advantages of this process are the bulbs become more tender and easier to absorb seasoning.
– Steaming is to cook with boiling water vapor so that foodstuffs are not in direct contact with water. Although it requires a longer time, this cooking method makes the colors, original taste and nutrition of food are maintained. Before entering tubers into the steamer, ensure the water in it is boiling so that tubers can be cooked evenly and simultaneously. If the water addition is needed, add boiling water instead of cold water, because the cold water will lower the temperature that affects the process of maturation and cooking results. Wrap the steamer lid with a thin cloth and cover the steamer tightly to prevent it from wet so steamed tubers can be cooked perfectly.
– Baking with the oven is considered the healthiest way because it makes the cooking time becomes short, so that the nutrients can be maintained with optimal foods. The principle is to make the food to be dried and baked in a closed hot oven. Preheat oven to a temperature corresponding to the foodstuffs to be baked and place food in heat-resistant container in the center of the oven rack in order to mature evenly. To bake sweet potatoes, especially “Cilembu” honey sweet potato, it should not be peeled to maintain the nutrient value. Peel when it’s cooked and ready to consume.
– Grilling is a method of cooking foods directly over the coals using direct fire, charcoal, wood, coconut shells or iron grills. Putting the tubers on top of the iron grills that were not preheated yet can make food stick and burnt so that the burner or grill should be preheated. If using charcoal, heat the charcoal properly. Once the fire are formed, move the furnace in order to flame continue to burn coal. Do not pour oil over the coals with the aim of speeding up the heating as it can cause harmful explosion effects. As is the case with oven roaster, roast potatoes without peeling them first, peel while to be served. Often tossing and turning cassava and sweet potatoes in order to prevent burnt & get them evenly matured. Sweet potato types “Cilembu” is preferred to be baked or grilled to release its honey content because the honey cannot be released by boiling or steaming it.
4. Cereals
Cereals are a group of plants that are grown for the seeds as a source of carbohydrates, such as rice, wheat, corn, oat and sorghum. For cereals, the food processing has major impact to the fiber content of food. The fiber content of food on white rice or white flour, for example, has been too much reduced compared to grain or whole wheat that has not been processed. Therefore, if we want to gain more benefits of fiber, we should select foods that still contain a lot of fiber such as brown rice than hulled rice, and whole wheat bread than white bread. In the cooking process, brown rice and brown rice requires more water than polished white rice. The higher the degree of milling, the whiter the color of milled rice produced, but the poorer nutrients content that are beneficial to the body, including dietary fiber.
5. Nuts
Boiling is the best way to process the nuts. Before boiling, preferably most types of nuts such as green beans and red beans soaked overnight so that the texture is soft and easy to be processed. For soybeans, the fermentation is the best way to process them as fermented soy products like tempe is easier to be digested and absorbed by the body. The fiber content in fermented soy beans also higher than soy beans that have not been fermented. Other processed nuts that also contain fiber goodness are peanut sauce and peanut butter.
The Indonesian version of this article has been published in Kulinologi Magazine (January 2015 edition)
References:
AACC Report (2001). “The Definition of Dietary Fibre”. Cereal Foods World (dalam bahasa English) 46: pp. 89–148. ISSN 0146-6283
Permenkes RI No. 033 Tahun 2012 Tentang Bahan Tambahan Pangan
Peraturan KBPOM RI No. 15 Tahun 2013 Tentang Batas Maksimum Penggunaan Bahan Tambahan Pangan Pengental
Peraturan KBPOM RI No. 20 Tahun 2013 Tentang Batas Maksimum Penggunaan Bahan Tambahan Pangan Pengemulsi
Peraturan KBPOM RI No. 24 Tahun 2013 Tentang Batas Maksimum Penggunaan Bahan Tambahan Pangan Penstabil
Peraturan KBPOM RI No. 25 Tahun 2013 Tentang Batas Maksimum Penggunaan Bahan Tambahan Pangan Peningkat Volume
Peraturan KBPOM RI No. HK.03.1.23.11.11.09909 Tahun 2011 Tentang Pengawasan Klaim dalam Label dan Iklan Pangan
Penuntun Praktikum Teknologi Pengolahan Pangan. 2001. Lab. Rekayasa Proses Pangan. Jurusan Teknologi Pangan dan Gizi. FATETA-IPB.
Tien R. Muchtadi dan Sugiyono. 1989. Petunjuk Laboratorium Ilmu Pengetahuan Bahan Pangan. Depdikbud, PAU Pangan dan Gizi, IPB.
Zulkarnain, M. R. 2015. Panduan Pengolahan pada Pangan kaya Serat Pangan. Kulinologi 1 vol VII 2015 (p. 33-36)