The effect of storage conditions on the physico-chemical and microbial properties of walnut cream

Walnut is one of the nuts, full of energy, protein, minerals and other nutrients. It also has plenty of oil, and that is why it can be turned into spreadable products. In this study, we evaluated the storage conditions of walnut spread (cream). For this, we prepared the walnut cream according to the formulation obtained by authors at preliminary experiments. We added 0-0.02% BHT as antioxidant to the formulation and packaged them in polyethylene jars. Then we stored the jars at 4, 25, or 40°C for 15, 55, and 90 days. After each storage time, the amount of oil separation, peroxide value, acidity and thiobarbituric acid value of the samples were determined. The analysis of the results showed that the oil separation was increased from 0.5% at 4°C to about 1.08% at 40°C. In addition, it was shown that after 15 days of storage the oil separation was only 0.47% and it was increased to 1.09% after 90 days. The peroxide value of samples was also increased from 2.13 at 4°C to 5.55 at 40°C. The addition of antioxidant decreased the peroxide value, however, this value was in acceptable range in the samples containing no antioxidant. The results of this study showed that the best temperature for storage of walnut cream was 4°C. At this temperature, we could store the walnut cream for more than 3 months without any artificial antioxidant.