Chemical,sensory and microbiological changes of gamma irradiated coconut cream powder

摘要

A study was carried out to determine optimum decontamination dose for a locally manufactured coconut cream powder.Samples were gamma irradiated(0-15kGy)and ageing process was achieved using GEER oven at 60 °C for 7 days,which is equivalent to one-year storage at room temperature.Iodine value(IV),ranging from 4.8 to 6.4,was not affected by radiation doses and storage,however peroxide value and thiobarbituric acid(TBA)generally increased with radiation doses.In most samples,peroxide value(meq/kg)reduced after storage,whilst the TBA(mg malonaldehyde/kg),indicator for product quality,slightly increased.The sensory evaluation conducted using 25 taste panellists indicated that scores on odour,creamy taste and overall acceptance for all irradiated samples at more than 5 kGy were significantly lower(P<0.05)than the control.However,the panellists could not detect any significant differences among the irradiation doses(P>0.05).All stored products were significantly different in colour,creamy taste,odour and overall acceptance(P<0.05)when compared to the non-stored non-irradiated control.Microbiological count of the samples prior to irradiation was in the range of 1 x 10~2 1.7 x 10~3cfu/g with no detection of Salmonella sp.and Escherichia coll.No microbial colonies were detected after irradiation.Based on the TBA and overall sensory acceptance,gamma irradiation of 5 kGy was found to be the optimum dose and lower doses can be considered to decontaminate coconut cream powder.