The two ingredients were chosen because of their popularity in the packaged food and beverage sector. At last month’s Natural Products Expo West, probiotics were a ubiquitous on-pack call-out on products from drinking vinegars to granola, and omega-3 fortified basics like milk and eggs are creeping more into households.
In fact, taking in omega-3 in beverage or food form is gaining more traction while the supplement category is in decline. Data from Packaged Facts indicated that North America and Europe posted flat sales, seeing only minimal growth with sales up an estimated 1.3% in 2016 from the year before to just over $1 billion. Meanwhile, trend forecasters such as those at ‘drink tank’ Imbibe believe there’s going to be an explosion for omega-3 beverage demand, given consumer familiarity to its benefits and advanced technology to minimize the fishy flavor.
“To date, there is no study which reports the digestion behavior of co-microencapsules containing two distinct bioactive ingredients such as omega-3 oil and probiotic bacteria,” the researchers wrote in their study, published in Food Chemistry.
Thus, the in vitro study was designed to observe the digestibility of co-microcapsules compared to microcapsules of just one ingredient (probiotic or omega-3) in terms of L. casei’s survival, as well as the release of omega-3 oil exposed to salivary, gastric, and intestinal fluids.
Preparing the ingredients
The probiotic strain used in the study, L. casei 431, was donated by Danish manufacturer Chr. Hansen. Tuna oil rich in DHA omega-3 fatty acids was donated by Australian firm NuMega Ingredients.
To encapsulate, the researchers used a combination (or ‘complex coacervate’) of whey protein isolate from Fonterra Cooperative and gum arabic from Sigma-Aldrich.
As a control, researchers microencapsulated probiotics and omega-3 separately in the complex coacervate, in addition to creating a version where both probiotics and omega-3 were microencapsulated together.
Presence of oil droplets protected probiotic from digestive fluids
Microencapsulations were observed as they were mixed with simulated digestive fluids in the oral phase, gastric phase, and intestinal phase.
Viability of L. casei was assessed in an agar using a spread plating technique. They found that the co-microencapsulated bacteria had a much higher survival rate than the non-encapsulated and single microencapsulated ones, though there was still a steady loss in viability for all three types.
“We observed that the stress from the simulated salivary, gastric and intestinal fluids on co-microencapsulated L. casei and microencapsulated L. casei were not similar,” the researchers wrote. This is because the aggregation of oil droplets in the mixture of probiotic, omega-3, whey protein isolate, and gum arabic created ‘multicore microcapsules’ when spray-dried, thus providing an oil barrier that came into contact to the digestive fluids before the bacteria did.
Higher concentration of chemically intact omega-3
In terms of the omega-3 released, the researchers found that there was decrease in omega-3 fatty acid content in oil extracted from the microencapsulated and co-microencapsulated varieties compared to pure tuna fish oil.
“The complex coacervation and spray drying processes might have caused this drop, possibly due to oxidative degradation,” they wrote.
However, they also noted that a significant retention of total omega-3 fatty acids was observed from the oil released from co-microcapsules compared to that of the single microencapsulated variety. “This may be due to the co-microencapsulation of omega-3 oil with probiotic bacteria providing better oxidative stability to omega-3 oil,” the researchers added.
Though increased survival and intestinal adhering ability of probiotic, as well as higher retention of microencapsulated omega-3 fatty acids in the digestive system posited advantages for co-microencapsulating the two together, there were still some shortcomings.
“The cholesterol assimilation ability of L. casei did not improve,” the researchers found, and they called for in-vivo clinical studies to further evaluate the survival, oxidative stability, and bioavailability of co-encapsulated probiotic bacteria and omega-3 fatty acids.
Source: Food Chemistry
Published online ahead of print, http://dx.doi.org/10.1016/j.foodchem.2017.01.080
“In-vitro digestion of probiotic bacteria and omega-3 oil co-microencapsulated in whey protein isolate-gum Arabic complex coacervates”
Authors: Divta Eratte, Kim Dowling, Colin J. Barrow, Benu P. Adhikari