Tanuja Muramalla, Luis Vargas, Behannis Mena, Olga Cueva, Najim Najim and Kayanush Aryana
Yogurt is a cultured dairy product that has a healthy image because of its nutritive value and beneficial bacteria. According to the legal description of yogurt, as described in the Code of Federal Regulations, Lactobacillus bulgaricus and Streptococcus thermophilus are two culture bacteria required in yogurt manufacture. In addition to their role in making yogurt, both bacteria impart several health benefits, including improving lactose digestion, providing immunostimulatory effects, and exhibiting anti-tumoral and anti-mutagenic activity, which is important in the treatment of cancer.
Lactobacillus acidophilus is a widely used probiotic bacterium with several health benefits, which include lowering cholesterol, reducing the occurrence of diarrhea in humans, providing immune support for infections or cancer and replacing bacteria in the intestinal tract following antibiotic therapy, and improving the symptoms of lactose intolerance. Lactobacillus acidophilus is used in approximately 80% of the yogurts manufactured in the United States.
One of the basic requirements for a culture to be called probiotic is the ability to survive the acid and bile conditions, which readily kill these beneficial bacteria, in the gastrointestinal (GI) tract. Hence, acid tolerance and bile tolerance are important probiotic characteristics. Enhancing these probiotic characteristics would facilitate more of these favorable bacterial cells to reach the lower GI tract “alive” to confer the health benefit upon the human host. Maintaining the functionality of bacterial cultures under GI tract conditions (acid and bile) has been one of the major challenges in developing probiotic products.
Two important aspects in creating new food products are ingredients and processing. Among the various dairy food ingredients, there has been an emphasis on proteins in diets. In milk, there are two types of proteins: caseins and whey proteins. Whey proteins are preferred over caseins because they are easier to digest because of their relatively smaller size, and they help in muscle building. In milk, the main component of total solids is lactose or milk sugar. Sugars are also known to facilitate microbial growth. LSU AgCenter researchers are studying how whey proteins and lactose enhance probiotic characteristics.
For processing foods, food safety needs to be considered. In dairy foods processing, pasteurization and ultra-high temperature treatments are commonly used. High temperatures alter the cell structure in bacteria, making it harder for them to live. Some of the other processes known to control microbial growth are high-pressure homogenization and pulsed electric fields. Application of high pressures mechanically disrupts the bacterial cell, thereby destroying it. Pulsed electric fields use short (less than 1 second) high-voltage pulses, which induce pores or holes in microbial cells, causing microbial inactivation. Just as high temperatures are used to kill pathogenic microorganisms and mild temperatures as in incubations are used to grow culture bacteria, AgCenter researchers are studying how “mild” homogenization pressures and “mild” pulsed electric fields enhance probiotic characteristics.
In conclusion, bacteria can accordingly be pre-treated prior to use for enhancing a targeted probiotic characteristic. Certain ingredient and processing treatments can help enhance probiotic characteristics.
Tanuja Muramalla, Luis Vargas, Behannis Mena and Olga Cueva are former students of Kayunush Aryana, who holds the Doyle Chambers Professorship in Animal Sciences. Najim Najim was a visiting scientist on a one-year sabbatical in the School of Nutrition and Food Sciences.
(This article appears in the fall 2019 issue of Louisiana Agriculture.)