Encapsulation of phenolic compounds which extracted from apple peels

Functional foods are foods which have health benefits that are in addition to those attributable to the nutritional value of the food. The term is usually applied to foods that have been modified or combined in order to enhance the health benefits but may include any food that naturally possesses components with demonstrable pharmacological activity. Food wastes contains these valuable components with complex ingredients. These valuable components usually named as functional compounds or bioactive compounds. In recent years, consumer demands great interests and regulatory agencies' tendency of having more natural food ingredients that have positive health effect has arisen the importance of these components which have similar preservation and additive quality. The polyphenolic compounds are used in numerous sectors of the food-processing industry as natural additives like natural coloring agents, conservative agents, natural antioxidants and nutritional additives. However, it is probably in the field of human health that the economic implication of polyphenols is the most important. Actually, many plant extracts rich in phenolic molecules of interest are used as food complements or can be integrated into cosmetic or pharmaceutical formulations. Functional compounds, specifically polyphenols named as phenolic compounds have considerable importance on human and animal diet because they associated with probable reduced risks of chronic diseases, they constitute pigments with a wide range of biological activities including antioxidant, anti-inflammatory, anticancer, antimutagenic, chemopreventive activities and may reduce the risk of coronary heart disease through modulation of arterial protection. Besides its benefits and biological activities, phenolics are not stable compounds. Phenolics are susceptible to degradation through factors such as the presence of light, pH (mainly pH higher than 7), temperatures higher than 60 – 80°C depending the phenolic group, the presence of sulfite, ascorbic acid, enzymes among other factors. Low stability of phenolics during food processing, storage and even during consumption brings new technological challenges. Functional compounds should be taken at adequate dose to reveal its health benefits. One of the big challenges is bioavailability of these components. Because of some drawbacks as low extraction percentages and their relative instability which is affected by physical and chemical factors, bioavailability of these compounds should be increased to effect in the specific tissue or organ. One possible way to effectively protect the phenolic compounds, from product processing to consumption, could be the use of micro or nano encapsulation techniques. Among different encapsulation techniques, liposom encapsulation technique is used because of its attractive properties like being easily applicable, hydrophobic and hydrophilic properties and way to different particle sized preparation. This study aimed to investigate encapsulation efficiency of phenolics by extracting from peel of the fruit apple which is commonly consumed and passed different processing steps, for determining how to use this extract as an ingredient to improve functional property of food. Thereby, aiming to open a door for waste recycling, to observe applicability of liposom entrapment method, whether encapsulation can protect functional compounds from degradation or other influences until gastric and intestinal environments, and if bioavailability improved by releasing of these compounds at targeted tissues. In this study encapsulation of chemical extraction of apple peel phenolics by using liposome entrapment method by microfluidic methods was applied. Different concentrations of apple peel extracts from 0.1 to 0.5 % was prepared and encapsulation method applied to these extracts. Particle size and zeta potential values were recorded. With these values physico-chemical properties of encapsulation were defined. Total phenolic content by Folin method, antioxidant capacity determination and total flavonoid content was measured thorough spectrophotometric analysis at different stages of encapsulation period like before encapsulation, after gel filtration process and after releasing phenolics by Triton treatment process to see the encapsulation efficiency. During optimization that conducted to observe encapsulation efficiency, the lowest extract containing capsules (0.1 %) showed highest negative zeta potential where result is -20.9 mV and highest particle size where result is 225.4 µm. Bigger particle size than empty liposome shows that capsullation achieved. Same extract (0.1 % extract containing capsules) showed highest capsulation rates and encapsulation efficiency where results are for total phenolic content, capsulation rate 32.5 %, encapsulation efficiency 78.5 %; for total flavonoid content capsulation rate 35.8 %, encapsulation efficiency 64.4 %; and for antioxidant activity analysis capsulation rate 31.1 %, encapsulation efficiency 92.3 %. With these results 0.1 percent preparation of apple peel extract with liposome will be more effective and used as optimized value. After optimization with more efficient encapsulation rate (0.1 %) liposom suspensions were prepared and coated with chitosan as second protective layer. For heat stability during spray drying maltodextrin was used as third layer and encapsulation completed. Then suspention dried with spray dryer to achive easy-to-use and get less degradable powder form. Powdered encapsulated extract mixed with food sample to observe efficiency and recovery of encapsulation by liposom entrapment with in vitro bioavailability method in which gastric and intestinal environment simulated. A fermented milk drink (kefir) is used as food medium. Before bioavailability and after bioavailability samples were analysed spectrofotometrically and chromatographically. Total phenolic content by Folin method, antioxidant capacity (CUPRAC and DPPH) determinations and total flavonoid content was measured thorough spectrophotometric analysis and phenolic compound composition and amount were measured by HPLC. When non-capsulated apple peel extracts and encapsulated extracts were compared and examined, it could be seen that total phenolic compund decreased from 1.87 mg/g to 0.61 mg/g; total flavonoid content not cahanged (0.30), antioxidant activities in DPPH it decreased from 0.55 mg/g to 0.06 mg/g, in CUPRAC assay decreased from 1.81 mg/g to 0.74 mg/g and with HPLC analysis total phenolic compounds decreased from 147,71 mg/g to 61,90 mg/g. These big changes in amounts can be indicator of that encapsulation succeeded and capsules protected active compounds effectively. Spectrofotometric analysis and chromatographic analysis showed that datas of liposom without extract and liposom with 0.1 % apple peel extract are nearly same and difference between means are not significantly important (p<0,05). However, results of non-capsulated apple peel extract were much bigger than encapsulated samples and significantly different (p<0,05) but after digestion treatment difference was not important and results were close to each for both capsulated and non-capsulated samples. Results that gained after application of in vitro digestion method, in which mouth, gastric media and intestines were simulated, were close to each other and it can be said that encapsulation with liposom and chitosan as secondary layer and maltodextrin as third layer protected bioactive compounds and then capsules released that compounds in intestines where they would be available for body absorbtion. As a result, with this study it can be suggested that encapsulation of apple peel extracts with liposom-chitosan-maltodextrin can improve stability of polyphenols during storage or digestion and bioavailability/bioaccessibility for body can be increased.