Study On The Processing Of A Healthy Labneh (Concentrated Yoghurt)

This research was conducted to prepare a healthy labneh (concentrated yoghurt) from skimmed milk powder with characteristics similar to labneh prepared from full-fat milk. Firstly, labneh, which is a semisolid product made from yoghurt by removing part of its water, was manufactured by using traditional method (cloth bag) and centrifugation. Centrifugation was carried out to concentrate warm yoghurt (at fermentation temperature 43±1°C), and cold yoghurt (stored overnight at 4°C), at 3000g for 5, 10, 20, and 30 min, respectively. Results showed that centrifugation of warm yoghurt at 3000g for 10 min could produce labneh with characteristics similar to that made by traditional method. Secondly, reduced-fat labneh samples were prepared from Reconstituted Skim Milk Powder RSMP (~14% total solid) with two different types of fat replacers namely inulin and whey powder at 1%, 3%, 5% and 7% levels. Labneh made from RSMP alone without addition of a fat replacer was elaborated as Control Labneh, while labneh made from full-fat milk was elaborated as Reference Labneh. Results indicated that incorporation of inulin at 5% in the RSMP was found enough to produce reduced-fat labneh with a quality similar to that of full-fat labneh, while incorporation of whey powder at 3% was enough to produce reduced-fat labneh with a quality similar to that of full-fat labneh. Finally, both labneh made from RSMP with inulin and labneh made from RSMP with whey powder were analyzed for total solid, protein, fat, pH, titratable acidity and mineral contents, in comparison with the Control and Reference Labnehs. Taste and/or flavor compounds such as fatty acids, amino acids, and small peptides were also analyzed. Results showed that labneh made from reconstituted skimmed milk powder with inulin and/or whey powder as fat substitutes had lower total solid and protein contents, but higher mineral content. However, fat, pH and titratable acidity did not differ significantly. The fatty acid composition of labneh samples made from RSMP with added inulin or whey powder was found to be higher than that of Control labneh, but closer to the one observed for Reference labneh. Amino acid content of labnehs made from RSMP containing inulin or whey powder was lower than the Control labneh, but higher than the Reference labneh. HPLC analysis revealed that the molecular weight range of the peptides from the inulin-containing labneh was lower than that of the whey powder-containing labneh and that of the Control labneh.In summary, results obtained from this research showed that a healthy labneh could be produced by centrifugation of warm yoghurt (at fermentation temperature 43±1°C, straight from the incubator), prepared from reconstituted skim milk powder fortified with inulin, at 3000g for 10 min.