Physico-chemical analysis and sensory evaluation of bread produced using different indigenous yeast isolates

Abstract

This study carried out the physico-chemical analysis and sensory evaluation of bread produced using different indigenous yeast isolates in order to offer an insight into the overall quality of the bread. Four (4) different yeast species were isolated from sweet orange, pineapple and palm wine. The yeasts were characterized and identified using the API 20C AUX kit. Each of the yeast isolates were used to ferment wheat flour dough. The specific volume, proximate analysis were carried out before baking. Commercial yeast served as positive control. The heavy metal analysis of the baked bread was investigated. The sensory evaluation of the baked bread was carried out with nine (9) point hedonic scale using ten (10) selected penalists. The yeasts were identified as Rhodotorula mucilagnosa, Rhodotorula minuta, Candida colliculosa and Candid krusei and the results of the physical properties obtained, showed that the bread sample CS2B had the highest specific volume (3.60cm³/g) while the negative control had the lowest value (2.03cm³/g). The proximate analysis of the bread samples revealed that the moisture content ranged from (0.2959-24.1), protein (3.325-5.425), fat (4.165-6.80), fibre (1.49-3.50), ash (1.331-3.1029), carbohydrate (43.325-89.112) and energy (256.20- 407.2298). The bread sample PW7B had the highest value of moisture (24.10), protein (4.90) and fat (7.45) while AC1B had the highest value of carbohydrate (89.11) and energy (407.23). No trace of lead and arsenic were found in all the bread samples, the value of iron, copper and calcium recorded falls within the permissible limit of FAO/WHO. The analysis showed that there was no significant difference (P>0.05) between the yeast isolates used to produce the bread and the perception of the different qualities of the bread. Generally, the bread samples were within the regulatory specifications of standard organisation of Nigeria (SON) and all the bread samples produced were generally accepted by the consumers in relation to their organoleptic properties. Fruits are excellent source of yeasts with dough fermenting abilities and bread of acceptable quality can be produced from these yeast isolates. The high proximate values of the bread samples recorded confirmed that they are capable of meeting most nutritional provisions as a staple food.

Keywords: Yeast isolates, bread, physico-chemical analysis, sensory quality