Abstract:The digestion rate and bioaccessibility of two different types of docosahexaenoic acid (DHA) algal oil products, namely DHA gel candy and DHA softgel, were evaluated using an in-vitro dynamic digestive system. The two DHA algal oil products were digested in vitro; their particle sizes, surface potentials, microstructures, and DHA contents were determined to evaluate their digestive characteristics. The results showed that in the pancreatin supplement group, the particle size of DHA gel candy was significantly smaller than that of DHA softgel (p<0.01) after 60 minutes of intestinal digestion. However, in the group without pancreatin, the particle size of softgel was significantly larger than that of gel candy (p<0.05) after 30–90 minutes of intestinal digestion. In the pancreatin supplement group, the zeta potential of the products from intestinal digestion of gel candy increased with time, and they were all higher than 30 mV. There was a sustained release of non-esterified fatty acid (NEFA) by gel candy, which gradually increased with time. In contrast, there was no obvious relationship between the NEFA released by softgels and digestion time. In addition, the digestion products of gel candy were in the form of small droplets with similar shape and size and uniform dispersion in fluorescent images, whereas those of softgels varied in shapes and sizes with non-uniform distribution. In summary, compared to DHA softgels, DHA gel candy is more easily digested, its oil is gradually released and sustained, and has a better dispersion performance at all stages of digestion. Moreover, the DHA content released by gel candies was 6.75 times that of softgel, indicating better bioaccessibility of gel candy.
