Location: Dairy and Functional Foods Research
2018 Annual Report
Objectives
1: Develop strains of dairy lactic acid bacteria (LAB) that excrete bioactive peptides and proteins which inhibit the growth of food-borne pathogens (Listeria), and/or the bacteria associated with non-food related diseases of the oral-pharyngeal cavity (streptococci), skin (propionibacteria) and gastrointestinal tract (clostridia).
1a. Characterize the broad spectrum antimicrobial activity of bacteriocins produced by dairy lactic acid bacteria, and investigate methods for optimizing their production for use in food and non-food applications.
1b. Investigate the molecular structures of bacteriocins produced by dairy lactic acid bacteria and elucidate mode of action pertaining to their antimicrobial activities.
2: Identify prebiotic and probiotic combinations which influence human health through interaction with bacteria from the gut microbiota and/or intestinal epithelial cells.
3: Identify dietary fiber and prebiotics from pectins and hemicelluloses in sugar beet, citrus, cranberry and energy crop biomass with additional bioactivity including anti-adhesion of pathogenic bacteria to epithelial cells and immunomodulation (anti-inflammation, cytokine expression).
Approach
A multi-disciplinary approach will be used to study bioactive food ingredients that influence the gut microbiome, and inhibit the growth of bacterial pathogens. We will develop prebiotic, probiotic and anti-microbial compounds produced by dairy lactic acid bacteria (LAB) as well as plant cell wall oligosaccharides. The potential for LAB bacteriocins to prevent contamination of foods, and infections within the gut and oral cavity as well as on the skin will be investigated. Novel prebiotics will be developed as another bioactive intervention used to control food-borne pathogens and to promote health. Protein structure-function relationships will be determined both for bacteriocins and the interaction between dietary fiber carbohydrates and dairy proteins. The probiotic properties of LAB, the effects of prebiotics on these beneficial bacteria, and the combination of the two as synbiotics will be investigated. The interface between how combinations of prebiotics and probiotics influence gut bacteria and epithelial cells will be investigated in model studies. Additional health-promoting bioactivities (anti-adhesion of pathogens and immunomodulation) of dietary fiber and plant cell wall oligosaccharides will also be examined.
Progress Report
Progress was made on all three objectives which address NP306 Component 1: Foods,
Problem Statement 1.B: New Bioactive Ingredients and Health-promoting Foods. For
Objective 1, completed studies on the production of bacteriocins by Streptococcus
thermophilus in various milk varieties. Results suggest that processing
technologies may reduce the effectiveness of antimicrobial peptides in milk.
Results showed that bacteriocin expression was lower in pasturized, homogenized
whole milk when compared with cream line (non-homogenized) whole milk or skim
milk. In addition, ultrasound treatment of raw milk was not shown to affect
bacteriocin production. These results suggest pasteurized skim milk is a
favorable growth medium for the development of fermentates for dairy food
applications; and that S. thermophilus cultures may function as protective
cultures in raw and skim milk dairy products. Preliminary studies have shown that
fermentation of milk with S. thermophilus B59671 can prevent the growth of
Listeria monocytogenes at refrigeration temperature, and reduce the number of
listeria after prolonged storage (4 weeks). Partially purified thermophilin did
not reduce the number of listeria in skim milk, suggesting that a low pH
environment may be necessary for anti-listerial activity in milk. Studies are
ongoing to test for improved anti-listerial activity by including additional
bacteriocin-producing lactic acid bacteria during fermentation; and to identify
the development of listeria strains resistant to thermophilins. Studies have also
been initiated to test the effect of thermophilins in combination with other oral
antimicrobials for activity against S. mutans. Collaboration with Buffalo
Research Institute (China) has resulted in the isolation of several novel lactic
acid bacteria strains, some of which have displayed antimicrobial activity against foodborne pathogens.
With regard to Objective 2, evidence exists that probiotics function optimally
when delivered with a prebiotic (non-digestible food ingredient) that promotes its
growth. Studies were conducted to identify dairy lactic acid bacteria, from
within the Eastern Regional Research Center (ERRC) culture collection, which could metabolize prebiotics as a primary carbon source. A panel of 85 lactobacillus strains were screened and 18 grew and generated lactic acid in a culture medium containing fructo-oligosaccharide, inulin and novel prebiotic oligosaccharides (citrus arabino-oligosaccharides, cranberry oligosaccharides, sorghum, corn fiber) as the only carbon source. Of the 85 strains, 18 were identified as being able to metabolize the prebiotics tested, and shown to produced short-chain fatty acids (acetic acid, proprionic acid), which are reported to assist in the health and well-being of mammalian hosts. These 18 strains represented 11 lactobacillus species, and will be used in future studies to screen novel oligosaccharides for prebiotic activity.
Under Objective 3, fermented tea (Kombucha) was analyzed to determine if it
contains probiotic bacteria or has health-promoting properties. Kombucha is a
healthy beverage synbiotic since it delivers bioactive tea polyphenols in a
cellulose matrix plus acetic acid and gluconic acid, not because of known
probiotic bacteria based on meta-genomic sequencing analysis. In CRADA research,
the key Kombucha process parameters including the type of tea, age of inoculum,
presence or absence of solid inoculum and specific interfacial area were evaluated
and correlated with chemical (sugars, acids, alcohol, catechins, total
polyphenols), microbial (bacteria and yeast counts, and composition) and sensory
characteristics. In CRADA research, identified cranberry pectic oligosaccharide
structures that could have prebiotic properties. Collected cranberry
oligosaccharides by preparative HPLC to produce enough for an ex vivo feeding
trial to be conducted by CRADA partner. In CRADA research, identified carrot fiber
pectic oligosaccharide structures with reduced molecular weight following
enzymatic treatment. We currently are collecting enough of these carrot pectic
oligosaccharides for prebiotic screening with our 18 Lactobacillus strains.
To better understand interactions between dairy proteins and pectin (prebiotic),
we investigated whey proteins as ready-to-drink functional protein beverage
ingredients. For reasons of safety and shelf-life, many beverage products,
especially those formulated at near neutral pH, require thermal pasteurization (72
°C for 15 sec) or as retort sterilization (120 °C for 15-20 min) or UHT processing
(140 °C for 3-4 sec). However, whey proteins are readily affected by heat, pH, and
salt concentration leading to undesirable traits such as turbidity, precipitation
and gelation. Therefore, we used whey proteins (3%) and varying levels of sugar
beet pectin (1 – 3%) in order to protect the whey. We demonstrated the
interactions between the protein and pectin occurred at the molecular level and
these interactions permitted improved functional properties such as emulsion and
thermal stability. These findings established a knowledge base for formulating
viable protein enriched beverages that also included soluble fiber and the
antioxidant compound (ferulic acid), which is an intrinsic component of the
pectin.
Accomplishments
1. Fermented tea healthy beverage. Functional foods that promote gut health are popular but there is a need for more scientific data to support health claims. ARS researchers at Wyndmoor, Pennsylvania, analyzed fermented tea (Kombucha) to determine if it contains health-promoting bacteria (probiotics). They found that Kombucha did not contain known probiotic bacteria but the acids and tea bioactive compounds present support its reputation as a healthy beverage. The Kombucha quality control process parameters determined by this research were adopted by the industry and new commercial Kombucha products were released. These results provide consumers with better functional foods that promote gut health and more knowledge about how Kombucha composition can be optimized for that end result.
Review Publications
Kale, M., Yadav, M.P., Chau, H.K., Hotchkiss, A.T. 2018. Molecular and functional properties of a xylanase hydrolysate of corn bran arabinoxylan. Carbohydrate Polymers. 181:119-123.
Rascon-Chu, A., Diaz-Baca, J.A., Carvajal-Millan, E., Perez-Lopez, E., Hotchkiss, A.T., Gonzalez-Rios, H., Balandran-Quintana, R., Campa-Mada, A. 2018. Electrosprayed core-shell composite microbeads based on pectin-arabinoxylans for insulin carrying: aggregation and size dispersion control. Polymers. 10(108):1-13.
Renye Jr, J.A., Needleman, D.S., Somkuti, G.A., Steinberg, D.H. 2017. Complete genome sequence of Streptococcus thermophilus B59671, which naturally produces the broad spectrum bacteriocin thermophilin 110. Genome Announcements. 5(45). https://doi.org/10.1128/genomeA.01213-17.
Bucci, A.J., Van Hekken, D.L., Tunick, M.H., Renye Jr, J.A., Tomasula, P.M. 2018. The effects of microfluidization on the physical, microbial, chemical, and coagulation properties of milk. Journal of Dairy Science. 101:1-12.
Wang, C., Liu, J., Duan, Z., Lao, Y., Qi, P.X., Ren, D. 2018. Effects of dietary antioxidant supplementation in cow’s feed, milk processing and storage on lutein content and sensory quality. International Journal of Dairy Technology. https://doi.org/10.1111/1471-0307.12532.
Qi, P.X., Xiao, Y., Wickham, E.D. 2018. Interactions, induced by heating, of whey protein isolate (WPI) with sugar beet pectin (SBP) in solution: comparisons with a dry-state maillard reaction. Food Hydrocolloids. https://doi.org/10.1016/j.foodhyd.2018.04.048.
