Effect of Fermentation Containers and Raw Materials on Chemical Composition and Sensory Quality of fermented cereals

Abstract

Effect of fermentation containers (plastic, wooden and earthen), cereals (millet, rice, maize and wheat) and cereal combinations (millet, rice and wheat) on chemical and sensory quality of fermented cereals were studied. Fermentation was carried out for 15 days at 26±2 ºC using defined starter made from S. cerevisiae and R. oryzae in rice flour. Finger millet fermented in plastic container had higher alcohol content (15.81% v/m) and TSS (11.96 ºBx) than that of earthen container while moisture and fixed acid contents remained unaffected. Total esters (1.813 g/l alc), total aldehyde (0.850 g/l alc), total acidity (1.58% m/m) and volatile acidity (0.296% m/m) were higher in millet fermented in earthen container. Fermentation containers had no significant (p>0.05) effect on the taste and smell of millet jand but color was comparatively superior in plastic container. Total ester (31.1 mg % m/v), TSS (3.97 ºBx), pH (4.67), total acid (0.41% m/v)) and fixed acid (0.37% m/v) contents were significantly higher in wheat jand compared to millet, rice, and maize jands, whereas no noticeable difference in volatile acidity (0.02 – 0.048% m/v) and alcohol (5.53 – 6.20% v/v) contents were found among four jands. Sensory evaluation showed that taste and smell of rice jand were superior (liked very much) while that of maize was rated as dislike slightly by the panelists. Addition of rice significantly increased the TSS of fermented millet while total acidity, fixed acidity and alcohol contents were not affected by cereal combinations. Addition of wheat decreased the ester content (0.431 g/l alc) to that of control (100% millet) (0.863 g/L alc). Total aldehyde content was significantly increased by both rice and wheat addition with a maximum value of 1.545 g/l alc in 20% rice added fermented millet. Finger millet substituted with 20% of rice had the maximum fusel oil (9.370 g/l alc) while a minimum value of 5.297 g/l alc was found in 20% wheat substituted fermented millet. Cereal combination did not have significant effect on methanol content and the values were in the range of 2.346 – 3.858 g/L alc. Addition of rice significantly increased the reducing and total sugar contents while 20% wheat addition decreased both the reducing and total sugar contents in fermented millet. Sensory evaluation revealed that cereal combination did not affect the color preference of jands, whereas addition of wheat significantly impaired the taste and smell of jand.DOI: http://dx.doi.org/10.3126/njst.v12i0.6521 Nepal Journal of Science and Technology 12 (2011) 330-339