The consumption of fat raises the risk of coronary heart disease and a number of chronic diseases such as obesity. However, removing fat or reducing its level in the final product may give it undesirable properties since fat plays an important role in the quality of food, mainly its texture and flavor. Therefore, natural or artificial fat replacers are utilized in food formulations instead of natural fat. Fat mimics are based on carbohydrates, proteins, and/or lipids, with energy values of 0–38 kJ/g (0–9 kcal/g). They mimic physical properties and sensory attributes of fat but have less energy and calories. Fat substitutes have physical and functional characteristics of conventional fat molecules which are directly replaced with synthetic molecules that provide no calories or structured lipid molecules. Dairy products represent a principal part of consumer diet all over the world. Therefore, this review aimed to expound how fat replacers can be used to overcome the defects of fat absence or reduction in dairy products. It was reviewed different types and sources of fat replacers, both micro- and nanoparticulated, and highlighted their application in cheese, ice cream, frozen yogurt, fermented milk, and fatty dairy products. Some of the currently applied micro-particulated proteins include Simplesse® (whey protein), APV LeanCreme™, and Dairy-Lo® (micro-particulate protein + micro-particulate cellulose). While whey protein has a great role in the dairy sector today, there is a need for further research in this field.

Our study was conducted in two stages; the first stage was to examine the fructose fermentation profile by Lactobacillus (Lb.) casei FEGY9973. The second stage was to investigate the viability properties of Lb. casei either during cold storage of labneh or under simulated gastrointestinal tract (GIT) conditions. Labneh as a carrier medium was classified into four treatments; the first one con- tained 2% free cells of Lb. casei as a control. The second, third and fourth treatments used 2% of encapsulated cells of Lb. casei with different capsule materials, including alginate-milk, sodium alginate and κ-carrageenan served as T1, T2 and T3 respectively. The physiochemical, microbiological and sensory properties of labneh during 15 days of cold storage were shown. Moreover, the viability of free and encapsulated Lb. casei sub- jected to some manufacturing and simulated GIT conditions was tested. It was revealed that lactate was the major metabolite in the medium for colonic fermentation, where- as no amounts of ethanol could be detected. Moreover, labneh samples including free cells of Lb. casei had lower pH values than treatments containing microcapsules of Lb. casei. The levels of moisture, acetaldehyde and diacetyle in treatments with different encapsulated materials were increased during the cold storage period. Accordingly, labneh samples with encapsulated Lb. casei had higher sensory scores than the control. In addition, labneh samples with Lb. casei in milk-alginate microcapsules showed a high viability during cold storage and under simulated GIT conditions. A significant decrease in the viability of free or encapsulated Lb. casei was observed at 15 days of cold storage. Encapsulated Lb. casei by alginate-milk was more resistant during the cold storage period and under simulated gastric conditions than the other two treatments.