The study, published in Food Hydrocolloids, noted that an increased awareness of healthier bakery products from consumers has led to ‘significant’ improvements in the health aspects of many products – including vitamin and mineral fortification and the reduction of salt, fat and sugar, plus gluten or allergen free products.
Led by Dr Ian Fisk from the University of Nottingham in the UK, the new research outlines a novel approach for the development of probiotic baked and cereal products using the example of pan bread with a film that contained the live bacterial strain Lactobacillus rhamnosus GG.
“The development of probiotic breads through the use of air dried probiotic edible films was found to be successful,” wrote the team – noting that the ‘correct’ design of the film forming solution was a critical factor in the viability of the probiotic bacteria.
“Based on our calculations, an individual 30–40 gram bread slice can deliver approx. 7.57–8.98 and 6.55–6.91 log colony forming units per portion before and after in-vitro digestion, meeting the WHO recommended required viable cell counts for probiotic bacteria to be delivered to the human host,” they stated.
“The presence of edible films did not modify the textural, flavour and thermophysical properties of bread crust samples indicating similar mechanisms of bread staling took place in both conventional and probiotic breads.”
Fisk and his team noted that over the last decade ‘significant research' has been carried out into the production of edible films with good barrier and mechanical properties and high levels of biodegradability. Recently, these edible films and coatings have been introduced as efficient carriers for the delivery of several bioactive compounds such as vitamins, antioxidants and probiotics in food systems, they added.
“Edible films therefore seem a very promising route for the delivery of probiotics in food systems where probiotics cannot be incorporated following the conventional approach of direct inoculation,” the team explained – noting that the heat and manufacturing processes involved in the production of many foods – including bakery products – make it unfeasible to directly incorporate probiotic bacteria in to a product.
“In the present work we demonstrate for the first time the application of probiotic edible films on a staple bakery system i.e. pan bread,” explained Fisk.
The team assessed probiotic pan bread made by the application of film forming solutions based either on individual hydrogels such as 1% w/w sodium alginate (ALG) or binary blends of 0.5% w/w sodium alginate and 2% whey protein concentrate (ALG/WPC) containing Lactobacillus rhamnosus GG.
They reported that no visual differences between the bread crust surface of control and probiotic bread were observed. However, the correct design of the film forming solution was reported to be a critical factor for the viability of L. rhamnosus GG during the air drying step, room temperature storage and simulated in-vitro digestion.
Indeed, the presence of whey proteins in the film forming solution reduced viability losses throughout drying and storage, while the use of film systems based exclusively on sodium alginate ‘exhibited a very good performance under in-vitro digestion.’
“The presence of the probiotic edible films did not modify cause major shifts in the mechanistic pathway of bread staling – as shown by physicochemical, thermal, texture and headspace analysis,” added the team.
Source: Food Hydrocolloids
Volume 39, Pages 231–242, doi: 10.1016/j.foodhyd.2014.01.023
“Probiotic edible films as a new strategy for developing functional bakery products: The case of pan bread”
Authors: Christos Soukoulis, Lina Yonekura, et al