Preparation,Physicochemical Properties And In Vitro Digestion Of Lipophilic Bioactives-enriched Delivery Systems Stabilized By OSA-starches

Lipophilic bioactives like,?-3 enriched oils,essential oils and fat soluble vitamins(?-carotene and ?-tocopherol)are required for normal body functioning and deficiency of these links to many chronic diseases.Applications of these lipophilic bioactives as a functional ingredient in food systems are limited due to their sensitive nature(high vulnerability towards oxidation).The physicochemical processes involved during processing,handling and storage limited the use of lipophilic bioactives in food and special cares are needed to overcome these limitations.Food industry is developing new strategies for fortification/enrichment of food with lipophilic bioactives to improve health and well-being of consumers.Nanoemulsions are considered an important tool for the protection,incorporation and delivery of lipophilic bioactives.In first part of the research,oil-in-water O/W nanoemulsions were prepared to encapsulate flax seed oil(rich source of ?-linolenic acid)and eugenol(antioxidant).Two octenyl succinic anhydride modified starches(OSA-MS)Purity Gum Ultra and Purity Gum 2000)were used as emulsifiers.The effect of eugenol(EUG)addition and emulsifier type on the size,charge,rheological properties and oxidative stability of flax seed oil(FSO)nanoemulsions stored under different temperatures(4,25 and 40 °C)for 4 weeks was investigated.Nanoemulsions stabilized by Purity Gum Ultra and Purity Gum-2000 showed 191.9 and 173.8 nm size,respectively.Nanoemulsions containing EUG,stabilized by Purity Gum Ultra,showed better physical and oxidative stability during storage as compared to Purity Gum 2000 stabilized emulsions.Results revealed higher % retention of ?-linolenic acid(ALA ? 66.3%)and EUG(? 63.2%)in Purity Gum Ultra stabilized emulsions containing FSO+EUG stored for 4 weeks at 40 oC as compared to Purity Gum 2000 stabilized emulsions containing FSO+EUG.This was attributed to the role of eugenol as antioxidant as well as the formation of a thick protective layer at interface by Purity Gum Ultra due to its higher molecular weight and density.In second part of the study,a three-stage in vitro digestion model was used to evaluate the influence of OSA-starch type on lipid digestion and bioaccessibility of ALA and EUG.Nanoemulsions were found stable to the mouth and gastric stages,however a considerable increase in size was observed as they passed through small intestinal stage due to the flocculation and coalescence as observed by confocal laser scanning microscope.The extent of lipolysis(67.52 ± 1.56)as well as bioaccessibility of ALA(83.63 ± 0.83)and EUG(77.97 ± 0.33%)was noted higher in Purity Gum 2000 stabilized emulsions as compared to Purity Gum Ultra emulsions.The better digestion properties of Purity Gum 2000 stabilized emulsions was attributed to the smaller emulsion size as well as lower molecular weight of Purity Gum-2000,which facilitated more exposure of droplets with the lipase and found more suitable for the delivery of ALA and EUG.In the next phase of research,?-carotene(BC)and ?-tocopherol(VE)were coencapsulated using long chain triglycerides(LCT)or medium chain triglycerides(MCT)as carrier oils and Purity Gum Ultra or Tween-80(TW)as emulsifiers.Nanoemulsions and bulk carrier oils containing bioactives were stored for 4 weeks to assess the effect of storage temperature on physicochemical properties.Oxidation behavior of bioactives was different in emulsions compared to bulk oil systems.The degradation of fat soluble vitamins(FSV)was higher at elevated temperature,which was more profound for BC.VE worked as antioxidant for the protection of BC in MCT based emulsions but it did not protect BC degradation in FSO based emulsions.However,incorporation of EUG improved the oxidative stability as well as retention of FSV in all emulsions.Nanoemulsions containing FSV and EUG stabilized by Purity Gum Ultra showed overall higher retention of BC(? 42%)and VE(? 90 %)after 4 weeks of storage at 40 °C.Better work of Purity Gum Ultra was due to its ability to form thick protective layer around oil droplets as compared to Tween-80.Influence of emulsifier and carrier oil type on in vitro digestion and bioaccessibility(BA)of multiple lipophilic bioactives encapsulated into nanoemulsion were also evaluated.Nanoemulsions showed a progressive increase in size as they passed throug simulated gastrointestinal phases(mouth,stomach,small intestine).The increase in size was more profond in Purity Gum Ultra stabilized emulsions due to flocculation and coalescence phenomena.The percentage of lipolysis was found higher in MCT based emulsions stabilized by Tween-80.The BA of lipophilic bioactives was found maximum in LCT based emulsions due to better solublization capacity and bigger hydrophobic core of LCT generated free fatty acids FFAs to accommodate large lipophilic bioactives.Emulsions stabilized by Purity Gum Ultra showed relatively higher BA of bioactives compared to Tween-80 emulsions.The maximum BA of bioactives was found in LCT based Purity Gum Ultra emulsion(BC: 73.8%;VE: 81.1%;EUG: 83.5%).In the last part of the research,BC and eugenol EUG co-encapsulated FSO emulsions stabilized by OSA-MS(Hi-Cap 100 and Purity Gum 2000)were spray dried to powders after the emulsification process.Microcapsules showed good dissolvation behavior,high(? 90%)microencapsulation efficiency and nearly round morphology observed by scanning electron microscopy.A 28 days storage test at 40 °C was carried out to evaluate the effect on physicochemical properties of microcapsules.Microcapsules encapsulated by lower Mw OSAMS(Hi-Cap 100)presented higher oxidative stability,lower moisture contents and water activity during storage compared to high Mw OSA-MS(Purity Gum 2000).Incorporation of EUG played its antioxidant role and further improved the oxidative stability as well as retention of core materials.Microcapsules of Hi-Cap 100 containing FSO+BC+EUG exhibited the maximum retention of BC(71%),EUG(84%)and ALA(92%).This study indicated better role of EUG as antioxidant and Hi-Cap 100 as wall material for the encapsulation of lipophilic bioactives that could be used for the development of functional foods and beverages.