Development and optimization of the production process for a composite snack bar for children 5 to 13 years

A thesis submitted to the Directorate of Research and Graduate Training in partial fulfillment of the requirements for the award of a Master of Science Degree in Agricultural Engineering of Makerere University.

Malnutrition is one of the major causes of morbidity among children worldwide especially in low- and middle-income countries like Uganda. As a result, many parents depend more on snacks and other fast foods for their children due to changing work trends and busier schedules. Many of the snacks and fast foods available on the market are high in carbohydrates and fat and low in protein and vitamins, and those that are more nutritious are usually more expensive and unaffordable to many consumers. The aim of this study was, therefore, to develop a nutritious snack bar for children 5 to 13 years as well as a semi-automated machine for its production. Mangoes, pineapples, carrots, lemon, raisins, honey and popped amaranth grain were used as the main ingredients in the production of the snack bar. The ingredients were selected basing on their nutritional and sensory attributes as well as their availability and price. The fruits and vegetables were cleaned, peeled, chopped into 3 mm thick slices and dried to 10% moisture content. The dried fruit portions were then weighed and mixed at 8 different levels within ranges obtained from Nutri-survey. The study also included the variation of amounts of honey added (30g to 80g) with compression force applied. The machine parts were made of stainless steel and aluminum, because of the materials availability, price, versatile machinability and requirements for food grade use. Efficiency of the machine was determined in consideration of quality of output and time taken to produce a batch of snack bars. A formulation with 60.0 g (42.9%) amaranth grain, 20 g (14.3%) mango, 25 g (17.9%) pineapple and 15 g (10.7%) carrot was found to yield the optimal snack bars with a composition of 12.17g/100g of Protein, Carbohydrates level of 71.56 %, Beta-carotene content of 15.82 mg/100 g, Vitamin C levels of 10.62 mg/100 g, Iron content of 5.44 mg/100 g, Zinc of 4. 35 mg/100 g, Fat content of 3.28 %, Fibre of 5.56 g/100 g, Ash of 5.43%, and Moisture content at 19.18 %. The composite snack bar also had desirable sensory quality and it was highly acceptable by all consumers with overall acceptability of score of 7.6. The designed machine had an efficiency of 74% and is capable of producing a total of forty-eight snack bars in 15 minutes. This production time was found to be half of the time usually used to manually produce the same number of snack bars. All this indicating that the machine has higher production rate and thus a more efficient option. The results of the snack bar in addition to the fabricated moulding tool can be used in the manufacture of snack bars and any other food products that require similar equipment.