Writing in the Journal of Functional Foods, the team behind the work impregnated the apple chunks with the probiotic Lactobacilllus casei and dried them at 10, 40 and 60 degrees Celsius, using either ultrasound-assisted or conventional air-drying. Led by scientists at the Universitat Politècnica de València and the Universidade Federal do Ceará (Brazil), the team said the resulting enriched apple cubes, which met the requirement to be classified as a probiotic food The use of ultrasound helped to reduce the drying time, without significantly affecting cell viability, the researchers explained. Sufficient numbers of Colony Forming Unit (CFU) microorganisms to meet the threshold of 1 million CFU/gram were obtained by using ultrasound-assisted drying at all temperatures, while conventional drying only produced a viable product at 60 degrees C. “Drying reduced the number of viable cells of Lactobacillus casei inoculated in apple samples, but drying at 60 °C or applying ultrasound provided a dried product with the required number of viable cells to produce a probiotic product (10 CFU/g),” commented senior author, Fabiano Fernandes from the Department of Food Technology, Universitat Politènica de València.
The recognised benefits of consuming probiotics and the trend towards increased fruit consumption, may make probiotic fruit products a popular means of providing significant health benefits, suggested the researchers. “They contribute to reducing the risk of cardiovascular diseases and type 2 diabetes, they have anti-inflammatory potential and protect against colitis, among other benefits,” said co-author Juan Andrés Cárcel, from the Analysis and Simulation of Agri-food Processes Group, Universitat Politècnica de València.
Perfecting viable dried probiotic foods has various advantages over dairy-based probiotics, proposed the researchers. As they require no refrigeration, the products would have increased shelf life, lower transportation and packaging costs. Additionally, they would be suitable for lactose intolerant individuals or those wishing to consume probiotics who did not like dairy. The technique might be extended to a range of other fruit and potentially vegetables. The probiotic dried fruit has applications not only as a healthy snack but also as a raw material in the food industry, said the researchers. Additionally, consuming moderate amounts of fruit would be an easy way of obtaining a large dose of probiotic bacteria. For example, “An intake of about 100 g of dried probiotic apple would impart in an intake of about 100 million (CFU) of the probiotic bacteria,” the researchers illustrated. Although the product requires further development, the potential is huge, the researchers suggested. “The concentration of probiotics in the apple snacks was similar to the concentration of microorganisms in commercial probiotic dairy products, thus proving that the production of dried probiotic apple snacks is possible and technically viable,” concluded the scientists.