Evaluation of the Factors Influencing the Content and Retention of Selected Heavy Metals in Milk and Some Dairy Products

摘要

The concentration and retention of some heavy metals in milk and milk products are closely dependent upon manufacturing process, ripening and storage. The present study deals with the assessment of selected trace elements such as Cd, Pb, Cu, Fe and Zn in milk as well as in fresh soft cheese (Domiati cheese and UF cheese ) hard cheese, Yoghurt and fatty products (crem, butter and ghee). The evaluation of the influence of manufacturing process on the concentration ranges of trace elements in milk products were carried out using Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). The results obtained showed that the retention% of heavy metals in the experimented cheese types (Domiati, UF and Ras cheese) showed some variation. The higher retention was obtained in UF cheese in Pb, Cd, Cu, and Zn, while lowest retention was obtained in fresh Ras cheese and also decreased during storage. The highest retention% was observed in Fe (12.76%) at the end of storage than other heavy metals in Ras cheese. The reduction levels obtained at the end of storage period were (17.04, 11.11, 10.6 and 15.8%) in yoghurt for Fe, Cu, Zn and Cr, respectively. While the reduction of Cd was 50% in yoghurt. Concerning Pb level in yoghurt no reduction was observed than that the level in raw milk . Further concentration of milk fat to butter and ghee decrease the retention% levels of all heavy metals than the retention% in cream out of starting amount in milk.