| Functional foods are either fortified with healthy ingredients(including bioactives such as fiber,phenolics and carotenoids,and nutrients such as vitamins,essential fatty acids and minerals)or they remove one of the unwanted components(such as sugar,salt or fat)from the composition.However,there are several limitations to the incorporation of bioactive substances in their own form into food formulations.Although solubility is the most important criterion for the selection of any bioactive substance in a food formulation,most bioactive substances(e.g.,fish oil)have low solubility in aqueous media.In addition,the shelf stability and bioavailability of bioactive substances may be reduced due to chemical degradation of food exposed to various environmental and handling conditions such as acidity,oxidation,light and temperature.As a result,these ingredients are often added to food formulations at high doses,thus affecting the sensory experience and economic aspects of the final product.In addition,there may be molecular interactions between fortified compounds and other food ingredients,which may reduce their biological activity.Encapsulation is an effective protection method.Oil is encapsulated in liquid form(such as lotion)and solid form(such as capsule).The choice of wall material plays a key role in this regard,and a suitable wall material not only protects fish oil from external factors,but also enhances the bioaccessibility of fish oil and achieves higher utilization value.Therefore,this paper focuses on fish oil encapsulation and explores the effects of wall materials on fish oil formulations in different forms(emulsions and capsules)using polysaccharides-sodium alginate and proteins-gelatin:(1)The differences of Span surfactants(Span 20,Span 40,Span 60,Span 80)on the performance of fish oil loaded sodium alginate/Span stabilized emulsions and calcium alginate/Span capsules were explored.Different spans of surfactants had different effects on emulsion emulsification and droplet stability.The addition of Span reduced the water content of the capsules and changed the particle morphology.The addition of Span 60 increased the fish oil loading rate(20.2% ± 1.4%)compared to calcium alginate capsules(12.2% ± 1.8%)(p<0.05).the addition of Span 20,Span 60 and Span 80 decreased the yield of primary lipid hydroperoxides in the capsules(p<0.05).the effect of Span surfactant on the gastrointestinal The effect of Span surfactant on free fatty acid release during digestion was different(p<0.05):Span 40 >Span 80 > control > Span 20 > Span 60.The present work shows that Span surfactant can modulate and optimize the performance of food emulsions and capsules.(2)Blending of encapsulating materials with small surfactant molecules was used to improve the performance of alginate based oil encapsulated formulations.The effects of blending with Tween series(Tween 20,40,60,80)on fish oil loaded sodium alginate stabilized dispersions and calcium alginate capsules were investigated.The results showed that for sodium alginate/surfactant stabilized emulsions,Tween 80 was the better emulsifier.The emulsification stability of all sodium alginate/Tween stabilized emulsions was higher than that of sodium alginate stabilized dispersions.The Tween series co-blends did not significantly change the particle size of calcium alginate capsules,but did not significantly decrease their water content and induced the formation of calcium alginate capsules with similar granular protrusions.The fish oil loading and encapsulation rate depended on the hydrophilic head and fatty acid fraction of the Tween series.Co-blending of the Tween series improves the oxidative stability of the fish oil capsules.During in vitro digestion,Tween containing saturated fatty acid fraction increased the release rate of FFA from the capsules(p<0.05),while Tween containing unsaturated fatty acid fraction had no significant effect on the release rate of FFA from the capsules.(3)Kraft gelatin nanoparticles were successfully prepared,while the morphology of the nanoparticles was fixed using o-phthalaldehyde as a cross-linking agent for modification.The nanoparticles prepared with different gelatin concentrations were characterized using scanning electron microscopy,atomic force microscopy,Malvern particle size measurement and ATR-FTIR.Pickering emulsions were also prepared using the prepared nanoparticles to encapsulate fish oil,and the differences were compared using water holding capacity(WHC),fat binding capacity(FBC),emulsion activity index(EAI)and emulsion stability index(ESI).The results showed that the nanoparticles and bovine skin gelatin(BSG)made at gelatin concentrations of 10 g/L and 24 g/L exhibited similar percentages of secondary structure in the α-helix and β-turn angle ranges.While the nanoparticles of 3 g/L,50 g/L and 100 g/L showed different percentages(p<0.05).the WHC values showed(p<0.05): 100 g/L>25 g/L>50g/L>10 g/L>5 g/L,we speculate that the WHC performance of gelatin nanoparticles may be proportional to the aggregation effect of large particles.the FBC values showed(p< 0.05): 10 g/L>25 g/L>100 g/L>50 g/L>5 g/L.It is noteworthy that all gelatin nanoparticles at 5 g/L exhibited the lowest level of water holding and fat binding ability.Taken together,the results of the above studies show that different surfactants in sodium alginate encapsulated fish oil would have an effect on its loading rate,in vitro digestion,oxidative stability and other indices.And o-phthalaldehyde did replace glutaraldehyde or kynurenine to prepare gelatin nanoparticles,and different gelatin concentrations caused effects on the physicochemical properties of nanoparticles.This study deepens the investigation of the patterns of surfactant effects on the properties of food emulsions and capsules,and it may also provide useful information for understanding the mechanisms of wall modification methods on the structure and function of emulsions or capsules.In addition,further studies are needed to explore the addition of other surfactants,the application of different wall materials in emulsions to improve the fish oil loading and physicochemical stability of emulsions and capsules. |
