Adding the prebiotic inulin to yoghurt boosted the growth of probiotic bacteria and, when used in a novel double-microencapsulation, extended the survival rates of the friendly bacteria.
The new research taps into the trend of probiotic encapsulation to extend by looking at the potential of seven prebiotic substrates on the viability of Lactobacillus acidophilus ATCC 43121 and the efficacy for the production of prebiotic-encapsulated probiotic.
"In the present study, the growth of L. acidophilus ATCC 43121 was significantly increased in the presence of three selected prebiotic substrates, FOS, lactulose and raffinose," wrote lead author Eun Ann in the International Journal of Food Science and Technology.
L. acidophilus has been linked to a number of health benefits, including improved immune system, lowered cholesterol contents, improved lactose intolerance, and reduction in occurrence of diarrhea in children and adults.
Probiotics are bacteria found in the gut that are understood to have health benefits. Prebiotics are ingredients that stimulate growth of probiotics in the gut, and synbiotics are a combination of the two.
Most foods containing probiotic bacteria are found in the refrigerated section of supermarkets as the bacteria is destroyed by heat and other processing conditions.
This has given the dairy sector, already used to handling live bacteria for the manufacture of yoghurt, a major advantage in probiotic foods - probiotic drinking yoghurts are currently the fastest growing dairy product in Europe.
But increasing research has focused on expanding protecting probiotics during processing and expanding the food categories available to prebiotics. Such an avenue of research has led companies like Cell Biotech from Korea using a dual-coating to protect probiotics against oxygen, acid, moisture and high temperatures for use in emerging new product categories such as breakfast cereals and smoothies.
Other approaches are also being explored, with scientists looking at improving probiotic viability by using whey protein gel particles, or prebiotic fibres.
Indeed, scientists from the Technical Research Centre of Finland (VTT) investigated the capabilities of various prebiotic fibres to protect the stability and viability of probiotic Lactobacillus rhamnosus strains during freeze-drying, storage in freeze-dried form and after formulation into apple juice and chocolate-coated breakfast cereals.
The researchers, from Louisiana State and Melborne University, studied seven different types of prebiotics to yogurt containing L. acidophilus. The prebiotics studied were: sorbitol, mannitol, lactulose, xylitol (all obtained from the Sigma), inulin (Raftilose HP, Orafti), fructooligosaccharide (Raftilose P95, Orafti) and raffinose (Difco).
Ann and co-workers report that cell growth of L. acidophilus was significantly increased in cultures containing 1.5 per cent lactulose, fructooligosaccharide, and raffinose.
"This indicates that L. acidophilus ATCC 43121 is able to effectively utilise FOS, lactulose and raffinose as a source of carbohydrates to promote growth but is unable to process the other tested substrates," said the researchers.
They then tested the efficacy of the prebiotics to encapsulate the probiotic, using a dry surface reforming process (hybridisation) using in combination with the coating material, Sureteric.
"Scanning and transmission electron microscopy showed that the double-microencapsulated bacteria exhibited smooth, rounded external surfaces, with a thick external coating composed of the prebiotic substrates and the Sureteric," wrote Ann.
The efficacy of this double-encapsulation was studied over a 36-day storage period, with the highest survival rates observed for the bacteria double-microencapsulation with FOS.
"Interestingly, after 36 days of storage at 25 degrees Celsius, the bacteria that were double-microencapsulated with FOS maintained a [stable] cell count," said the researchers.
"These results indicate that double-microencapsulation of L. acidophilus ATCC 43121 by hybridisation is useful to effectively provide beneficial effects of probiotic bacteria for the host," they concluded.
Source: International Journal of Food Science and Technology
Volume 42, Pages 411-419
"Microencapsulation of Lactobacillus acidophilus ATCC 43121 with prebiotic substrates using a hybridisation system"
Authors: E.Y. Ann, Y. Kim, S. Oh, J.-Y. Imm, D.-J. Park, K.S. Han, S.H. Kim