Product and Process Development of Ready to Eat Sorghum-green Gram Cookies Enriched With Mango Powder

Abstract

The triple burden of malnutrition is still a major challenge in most developing countries including Kenya. Currently, the increased dependence on convenience foods has contributed an increased consumption of energy-dense and nutrient poor snacks which have been associated with rising trend in non-communicable diseases. The utilization of healthier options for these products such as cereals and legumes can help improve the convenience food trend as well as address malnutrition problems in Kenya. Despite sorghum being a powerhouse of nutrition, it is still one of the highly underutilized cereals in Kenya with most of the sorghum products utilization being limited only at the household level. The basis of this research was therefore to develop and optimize the processing of Ready to Eat (RTE) sorghum-based products to address the underutilization of cereals and legumes through value addition and commercialization. The study employed an experimental study design with factorial arrangements of 3 treatments (whole grain, malted, fermented) sorghum at different levels of substitution with green gram flour supplemented with dried mango powder. Further, the study sought to determine the nutritional properties, consumer acceptability and shelf-storability of the developed cookies. The study also sought to determine the effects of malting and fermentation as well as addition of green gram flour to the properties analyzed. Malting, fermentation and addition of green gram flour significantly improved (p < 0.05) the protein contents of the cookies. Ash, protein, fat and fiber contents of the cookies increased significantly (p<0.05) with increased substitution with green gram flour while carbohydrates decreased significantly from 61.68 to 54.18%. Cookies from malted sorghum flour had the highest in vitro protein digestibility with values ranging from 90.05% - 86.44%. Vitamin (B1, B2, C) increased significantly (p ≤ 0.05) with malting and fermentation of sorghum flour. Iron and zinc contents were highest in fermented cookies at 60% (2.69 ± 0.02 mg/100g), and 60% (4.64 ± 0.08 mg/100g) while Calcium was highest in cookies from malted sorghum flour at 60% (44.48 ± 0.13 mg/100g). Malting and fermentation of sorghum significantly lowered the phytate content by 36.62% and 41.10% and tannin content by 16.16% and 25.36% respectively. Significant differences (p < 0.05) were observed in the phenolic contents of the cookies. Highest phenolic contents were observed in whole grain sorghum (60:30:10) - 382.3 mg/100g and fermented sorghum (60:30:10) - 427.2 mg/100g samples. Cookies from malted sorghum flour registered the lowest values of phenolic contents between 338.3 mg/100g to 363.7 mg/100g respectively. Overall acceptability of the cookies was highest in fermented cookies with a score range between 6.8 – 7.5. Most acceptable product was from fermented sorghum flour at 60:30:10 (Sorghum: Green gram: Mango powder) substitution level. Cookies from malted and whole grain sorghum were also above acceptable limits. The formulated products were packed into two different packaging materials - laminated resealable pouches and certified thermopack recyclable plastic containers- then subjected to storage under accelerated conditions (550C and 55% RH) where microbial load and peroxide values were monitored daily for 5 days. The microbial load and peroxide value increased significantly (p<0.05) in both packaging materials during the storage period however products packed in laminated resealable pouches exhibited better keeping quality. Shelf-life analysis showed a shelf stability of 3 months for the formulated cookies with no visible yeasts and mold spoilage. The study found that optimization of the malting and fermentation processes can be applied with sorghum grain processing for commercialization of baked products with improved nutritional, microbial and sensory attributes in an effort to promote food and nutrition security in Kenya.