Technological Aspects of Preparing Porridges Made from Local Crops in Mozambique

Abstract

Child malnutrition is one of the major health problems in many developing countries and involves many sectors such as health, agriculture and research. Malnutrition in infants usually develops during the introduction of complementary foods, due to a deficit of nutrients, low energy density and the poor bioavailability of vitamins and minerals leading, in turn, to an increase in the risk of disease and infant mortality. These complementary foods are usually prepared from starchy plants, the flour being heated with water causing swelling, resulting in a viscous porridge that is not suitable for consumption by small children. To circumvent this problem, it is common practice to dilute the porridge with water, which further reduces its nutritional value. Meat is often unaffordable for most of the population in the developing countries, while starchy crops are readily available. The aim of this study was, therefore, to investigate the use of locally available crops to produce complementary porridges with a palatable consistency, while maintaining the nutritional quality and energy density.



Flours were produced from various crops: orange-fleshed sweet potato, cowpea, maize, sorghum and soybean. Three methods of measuring the swelling were investigated (centrifugation, gravity sedimentation and least gelation concentration), and the consistency of the porridges made from each flour was measured with the back-extrusion method. It was not possible to predict the consistency of the porridges based on the results of the swelling measurements, but it was possible to estimate the flour concentration that would give porridge with an acceptable consistency preferably using the gravity sedimentation method. Based on the results obtained for the consistency and assuming that the volume fraction contributions from different flours were additive, all possible two-flour combinations were investigated, all mixes gave a porridge with low consistency or in the predicted range.



Fresh orange-fleshed sweet potato and cassava flour were used to develop a new product similar to garri, by roasting. The retention of β-carotene, the consistency, energy density and the consumer acceptance were evaluated. The higher retention of β-carotene (88%), overall preference (above 60%) and a significant reduction in viscosity made this product a promising source of precursor of vitamin A, while having a high energy density.



Linear programming was used in an attempt to formulate a nutritious and affordable complementary food for children aged 1-8 years, using locally available crops. It was not possible to formulate a food with an acceptable nutritional value and consistency, using locally available crops that would be affordable for most rural residents of Mozambique. However, if the cost of supplemental micronutrients such as zinc and calcium can be reduced, the cost of this food could be reduced by more than 70%.

Abstract (Swedish)

Popular Abstract in English

Malnutrition is one of the problems affecting many developing countries, sometimes leading to disease and death. Complementary foods, especially infant porridges prepared by families in rural areas, are based on plants (cereals, roots and tubers). These porridges are mainly composed of starch, and when mixed with hot water the starch gelatinizes and swells, resulting in a thick porridge that cannot be eaten by small children. It is therefore common to dilute these thick porridges making it necessary for the child to consume large quantities. However, dilution reduces the energy density and the nutritional value of the porridge. Several complementary foods have been developed by research groups and the food industry, and greater attention is being paid to locally available crops in order to retain local traditions and to minimize the cost of the final product. However, little information is available on the consistency of these foods.

Porridges were prepared from flour made from local crops, and their consistency was predicted using the consistency of commercial instantaneous porridges as references. Using the model for consistency obtained from porridges prepared from individual flours, the consistency of porridges prepared from mixtures of two flours was predicted. A new product (G-OFSP) was then developed by roasting a mixture of two well-known locally grown crops, namely white cassava and orange-fleshed sweet potato. This new product has similar characteristics to a product known locally as rale, called garri in West Africa. The acceptability and consistency of the new product by the rural population were investigated. As this new kind of garri contains components that are easily degraded by heat, in particular carotenoids, the retention of carotenoids during the roasting process was investigated. Finally, a model was developed to help in the formulation of palatable foods with high nutritional value based on local crops using linear programming, in which the consistency was one of the governing factors.

It was found to be possible to estimate the amount of flour resulting in a porridge with an acceptable consistency. Using the consistency of porridges prepared from individual flours, porridges based on a mixture of two flours were formulated. In some cases, it was possible to predict the consistency of these porridges. However, for all mixtures containing germinated maize and some mixtures containing cowpea, the experimental results were below the predictions. This reduction in consistency in the mixtures including germinated maize may be to the proteolytic and amylolytic activities of germinated maize, which may have degraded the starch in the other flour used in the mixture. For some mixtures including cowpea flour the reduction in the consistency may have been due to the difference in particle size of the two flours. Smaller particles are accommodated in the interstices between larger particles preventing their swelling, and leading to a reduction in consistency.

The G-OFSP was ranked highest in the overall acceptance test, being preferred by more than 60% of the panellists. The energy density was almost twice that of the garri made from cassava using the amount of flour that gave porridge with an acceptable consistency. This new product may offer a means of improving the energy density and nutrients intake.

It is known that the level of β-carotene is reduced by degradation during heat treatment in the presence of oxygen. A high retention of β-carotene was observed in G-OFSP (about 88%) made from roasted orange-fleshed sweet potato and white cassava. This can be compared with 43% found in yellow cassava garri. It was therefore concluded that the β-carotene was less degraded in the process used to make G-OFSP. The lower levels of β-carotene in yellow cassava garri may be due to fermentation, as well as the temperature and time used in the roasting process. It is thus possible to provide about 51% of the safe daily-recommended intake level of vitamin A to children of preschool age, using G-OFSP.

Based on the values of porridge consistency obtained experimentally, linear programming was used in an attempt to formulate nutritious and affordable food for children aged 1-8 years using locally available crops. However, it was not possible to formulate a food with acceptable nutritional value and consistency, which would be affordable by most of the rural Mozambican population. If micronutrients such as zinc and calcium were available at affordable prices, the cost of this food could be reduced by more than 70% and linear programming could be used to formulate foods that fulfil both nutritional and sensory requirements.

• author: Carvalho, Irene
• supervisor: Yvonne Granfeldt
• opponent: ASSOCIATE PROFESSOR KIDMOSE, ULLA, Aarhus University, Denmark
• organization: Department of Food Technology, Engineering and Nutrition
• publishing date: 2014
• type: Thesis
• publication status: published
• subject: Food Engineering
• keywords: Child malnutrition, consistency, complementary porridge, developing countries, energy density, carotenoids
• pages: 158 pages
• defense location: Lecture Hall B, Center for Chemistry and Chemical Engineering, Getingevägen 60, Lund University, Faculty of Engineering LTH, Lund
• defense date: 2014-11-28 10:15:00
• ISBN: 978-91-7422-375-0
• language: English
• LU publication?: yes
• id: ab08e213-f5fe-4182-bbb3-c4bd48152f34 (old id 4738882)
• date added to LUP: 2016-04-04 14:25:33
• date last changed: 2024-01-30 10:28:43