Abstract

This study investigated the use of African walnut oil to improve the physical, chemical, sensory and microbiological quality of cream during storage in the refrigerator at 4^oC. Cream was prepared and divided into four equal parts; the first part without oil served as fresh sample (control), the second to fourth part had 0.5%, 1.0% and 1.5% concentrations of African walnut oil added separately and stored for 15, 30 and 45 days in the refrigerator at 4^oC. Physical and chemical properties of cream indicated that additions of African walnut oil in different concentrations resulted to increase in peroxide and refractive values and decrease in acidity, saponification and iodine values of cream during storage 15, 30 and 45 days. Sensory score results showed that cream with 0.5 % African walnut oil was most acceptable by the panelists. Microbial examination of cream samples when fresh and during storage with and without the addition of 0.5 %, 1.0 % and 1.5 % African walnut oil led to the non-detection of proteolytic and lipolytic bacteria during 15 and 30 days storage except 45 days. At 45 days storage period, the proteolytic bacterial count of fresh control cream was 10 x 10¹ and cream samples had 6 x 10¹, 9 x 10¹ and 8 x 10¹ while lipolytic bacterial count for fresh control cream was 9 x 10³ and cream samples had 4 x 10¹, 7 x 10¹ and 3 x 10¹. Coliforms, yeasts and molds were not detected in all the cream samples.

Key Words: African walnut oil, Cream, Physicochemical properties, Sensory properties, Microbiological examination