غنی‌ ‌سازی پودر شیر با اسید لینولئیک کونژوگه (CLA) ریزپوشانی شده با استفاده از خشک کن پاششی و بررسی ویژگی‌های آن

Introduction:
Encapsulation is a process to entrap active agents within a carrier material and it is a useful tool to improve delivery of bioactive molecules and living cells into foods. Materials used for design of protective shell of encapsulates must be food-grade, biodegradable and able to form a barrier between the internal phase and its surroundings. Among all materials, the most widely used for encapsulation in food applications are polysaccharides. Proteins and lipids are also appropriate for encapsulation (Nedovic et al., 2011). The health benefits of omega-3 fatty acids are substantiated through extensive and rigorous in vivo studies. A wide range of investigation indicates that omega-3 fatty acids are essential not only for normal growth and development but also for their positive effects on heart, brain, eyes, joints, skin, mood and behavior (Kaushik et al., 2015). Omega-3 fatty acids are also implicated in the prevention of coronary artery disease, hypertension, diabetes, arthritis, other inflammatory and autoimmune disorders, and cancer. Many studies encourage the adequate intake of omega-3 fatty acids by pregnant and lactating women to support overall health of foetal and healthy development of retina and brain in foetus (Kaushik et al., 2015).Some studies argue that the claimed health benefits of omega-3 fatty acids are inconclusive, particularly with regard to cardiovascular events, cancer, cognitive health and slowing down the age-related macular degeneration (AMD). Desired levels of omega-3 fatty acids in diets can be achieved by including various foods enriched with omega-3 PUFA. Although a variety of food products enriched with omega-3 fatty acids are available in the market, there are technical challenges in their production, transportation, storage, bioavailability and sensory acceptability (Kaushik et al., 2015). The physical and chemical characteristics of omega-3 oils limit their application as a potential food ingredient. Due to the highly unsaturated nature of omega-3 fatty acids such as CLA, these are susceptible to oxidation and readily produce hydroperoxides, off flavours and odours, which are deemed undesirable by consumers. To overcome the above mentioned problems, the use of microencapsulation technology has been explored by various researchers (Kaushik et al., 2015). Omega-3 fatty acids have been microencapsulated using different encapsulation techniques. So far, spray drying, complex coacervation and extrusion are the most commonly used commercial techniques for microencapsulation of omega-3 fatty acids. Spray drying offers many advantages over other drying methods such as freeze drying, including low operational cost, ability to handle heat-sensitive materials, readily available machinery and reliable operation and ability to control the mean particle size of the powders for spray dried emulsions. However, only limited numbers of wall materials are compatible with this technology (Kaushik et al., 2015). The spray drying technique is considered an immobilization technology rather than an encapsulation technology because some bioactive compounds can be exposed superficially on microparticles. In addition to the simplicity of spray drying, this technique is also convenient for encapsulating heat-sensitive materials because the exposure time to elevated temperatures is short (5–30 s) (Rigolon et al. 2024). For the microcapsules to be formed, there is a need to use encapsulating materials, with polysaccharides being the most used for this purpose. The polysaccharides used have desirable properties such as low viscosity, high solid content, good solubility, readily available, biocompatible, form bonds with flavor compounds, exist in great diversity, have low cost and low toxicity (Rigolon et al. 2024). In a recent study, it was evaluated the potential of maltodextrin combination with different wall materials (starch, whey protein concentrate and gum arabic) for microencapsulation of flaxseed oil through spray drying. Results indicated that maltodextrin (MD) in combination with modified starches gave the best encapsulation efficiency in comparison to a gum arabic and whey protein concentrate (WPC) combination. Whereas the best emulsion stability and oxidation protection was observed in MD–WPC combination (Kaushik et al., 2015).Spray drying is the most extensively applied encapsulation technique in the food industry because it is flexible, continuous, but more important an economical operation. The purpose of this research is to investigate the production of nanocapsules containing different wall materials for conjugated linoleic acid and then enrich milk powder with it and enrichment of milk powder and evaluation of its properties.
Material & methods: In this research, 4 different treatments including: 1- xanthan gum and maltodextrin, 2- xanthan gum and whey protein, 3- guar gum and maltodextrin, and 4- guar gum and whey protein were used as wall materials. After drying the primary emulsions and milk (1/5% Fat) separately, the milk powder was enriched with nanocapsules powder. Some physicochemical characteristics of enriched milk powder including protein, fat, moisture, solubility and morphology were evaluated.

Results and discussion: The results showed that the performance of the spray dryer was about 50%. The most CLA content and encapsulation efficiency were related to the xanthan- whey protein (19.21%). the results of the evaluation of particle size and morphology indicated that in all treatments, the particle size was within nanometer, also the form of the nanocapsules was spherical and their surface had some cracks. The results of evaluating the characteristics of milk powder enriched with CLA showed that the samples of enriched milk powder were not significantly different from each other in terms of solubility (99%) and moisture content (2.33- 2.98%). However, there was a significant difference in the amount of fat and protein. the most amount of protein was related to the treatment of CLA encapsulated in whey protein-xanthan (12.83%). Also, the treatment containing xanthan-whey protein had the most amount of fat between all treatments. The results of fatty acid profile indicated that the most fatty acids detected in enriched milk powder were saturated, monounsaturated and polyunsaturated fatty acids, respectively.
Conclusion: According to the tests examined in this research, it can be concluded that the all tretments had good performance and can be used for encapsulating of fatty acids, vitamins, oils and flavors, but the xanthan-whey protein had better characteristics than the other treatments and was more suitable for encapsulation.

8%). However, there was a significant difference in the amount of fat and protein. the most amount of protein was related to the treatment of CLA encapsulated in whey protein-xanthan (12.83%). Also, the treatment containing xanthan-whey protein had the most amount of fat between all treatments. The results of fatty acid profile indicated that the most fatty acids detected in enriched milk powder were saturated, monounsaturated and polyunsaturated fatty acids, respectively.
Conclusion: According to the tests examined in this research, it can be concluded that the all tretments had good performance and can be used for encapsulating of fatty acids, vitamins, oils and flavors, but the xanthan-whey protein had better characteristics than the other treatments and was more suitable for encapsulation
8%). However, there was a significant difference in the amount of fat and protein. the most amount of protein was related to the treatment of CLA encapsulated in whey protein-xanthan (12.83%). Also, the treatment containing xanthan-whey protein had the most amount of fat between all treatments. The results of fatty acid profile indicated that the most fatty acids detected in enriched milk powder were saturated, monounsaturated and polyunsaturated fatty acids, respectively.
Conclusion: According to the tests examined in this research, it can be concluded that the all tretments had good performance and can be used for encapsulating of fatty acids, vitamins, oils and flavors, but the xanthan-whey protein had better characteristics than the other treatments and was more suitable for encapsulation
8%). However, there was a significant difference in the amount of fat and protein. the most amount of protein was related to the treatment of CLA encapsulated in whey protein-xanthan (12.83%). Also, the treatment containing xanthan-whey protein had the most amount of fat between all treatments. The results of fatty acid profile indicated that the most fatty acids detected in enriched milk powder were saturated, monounsaturated and polyunsaturated fatty acids, respectively.
Conclusion: According to the tests examined in this research, it can be concluded that the all tretments had good performance and can be used for encapsulating of fatty acids, vitamins, oils and flavors, but the xanthan-whey protein had better characteristics than the other treatments and was more suitable for encapsulation
8%). However, there was a significant difference in the amount of fat and protein. the most amount of protein was related to the treatment of CLA encapsulated in whey protein-xanthan (12.83%). Also, the treatment containing xanthan-whey protein had the most amount of fat between all treatments. The results of fatty acid profile indicated that the most fatty acids detected in enriched milk powder were saturated, monounsaturated and polyunsaturated fatty acids, respectively.
Conclusion: According to the tests examined in this research, it can be concluded that the all tretments had good performance and can be used for encapsulating of fatty acids, vitamins, oils and flavors, but the xanthan-whey protein had better characteristics than the other treatments and was more suitable for encapsulation
8%). However, there was a significant difference in the amount of fat and protein. the most amount of protein was related to the treatment of CLA encapsulated in whey protein-xanthan (12.83%). Also, the treatment containing xanthan-whey protein had the most amount of fat between all treatments. The results of fatty acid profile indicated that the most fatty acids detected in enriched milk powder were saturated, monounsaturated and polyunsaturated fatty acids, respectively.
Conclusion: According to the tests examined in this research, it can be concluded that the all tretments had good performance and can be used for encapsulating of fatty acids, vitamins, oils and flavors, but the xanthan-whey protein had better characteristics than the other treatments and was more suitable for encapsulation