Joellen M. Feirtag

Effects of dietary inulin on serum lipids, blood glucose and the gastrointestinal environment in hypercholesterolemic men

Abstract Inulin is a complex carbohydrate that belongs to a class of compounds known as fructans. Inulin has been consumed in plant sources by mankind for centuries, and is most concentrated in chicory, Jerusalem artichoke, garlic, leek and onion. It can be extracted from purified concentrated sources such as chicory root, and used to enhance the technological and nutritional properties of foods. Inulin is thought to share many of the properties of soluble dietary fibers, such as the ability to lower blood lipids and stabilize blood glucose. Additionally, inulin has been shown to enhance the growth of bifidobacteria and lactobacilli and enhance the gut environment. The objective of this study was to examine the effect of a commercially available inulin from chicory root (degree of polymerization (DP) ranging between 2 and 60, modal DP=9) in men with hypercholesterolemia on serum parameters and fecal composition. The study was a randomized, double blind, crossover design with no washout period. Twelve men were randomly assigned to two controlled diets that differed only in that the control diet contained one pint of vanilla ice cream made with sucrose while the inulin containing diet was supplemented with one pint of vanilla ice cream made with 20 grams of inulin. Subjects consumed each controlled diet for three weeks. Daily intake of 20 g of inulin significantly reduced serum triglycerides by 40 mg/dL (p=0.05). A trend toward a reduction in serum cholesterol was observed. Trends toward short chain fatty acid (SCFA) profile changes were observed after inulin administration. Transit time did not differ significantly between treatments. These data suggest that dietary inulin supplementation may improve blood lipid profiles and alters the colonic environment in a manner that may be beneficial. Because inulin is easily incorporated into an acceptable food like low-fat vanilla ice cream, it shows promise as a functional ingredient in many processed foods.

Reduction of Escherichia coli O157:H7 viability on leafy green vegetables by treatment with a bacteriophage mixture and trans-cinnamaldehyde

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 has been recognized as a major foodborne pathogen responsible for frequent gastroenteritis outbreaks. Phages and essential oils can be used as a natural antimicrobial method to reduce bacterial pathogens from the food supply. The objective of this study was to determine the effect of a bacteriophage cocktail, BEC8, alone and in combination with the essential oil trans-cinnameldehyde (TC) on the viability of a mixture of EHEC O157:H7 strains applied on whole baby romaine lettuce and baby spinach leaves. The EHEC O157:H7 strains used were Nal(R) mutants of EK27, ATCC 43895, and 472. Exponentially growing cells from tryptic soy (TS) broth cultures were spot inoculated on leaves and dried. EHEC cells were placed at low, medium, and high inoculum levels (10(4), 10(5), and 10(6) CFU/mL, respectively). Appropriate controls, BEC8 (approx. 10(6) PFU/leaf), and TC (0.5% v/v) were applied on treated leaves. The leaves were incubated at 4, 8, 23, and 37 °C in Petri dishes with moistened filter papers. EHEC survival was determined using standard plate count on nalidixic acid (50 μg/mL) Sorbitol MacConkey agar. No survivors were detected when both leaves were treated with BEC8 or TC individually at low inoculum levels after 24 h at 23 and 37 °C. When the EHEC inoculum size increased and/or incubation temperature decreased, the efficacy of BEC8 and TC decreased. However, when the two treatments were combined, no survivors were detected after 10 min at all temperatures and inoculum levels on both leafy greens. These results indicated that the BEC8/TC combination was highly effective against EHEC on both leafy greens. This combination could potentially be used as an antimicrobial to inactivate EHEC O157:H7 and reduce their incidence in the food chain.

Helicobacter pylori: Characteristics, pathogenicity, detection methods and mode of transmission implicating foods and water

Helicobacter pylori is an organism involved in the pathogenesis of human active chronic gastritis, peptic and duodenal ulcer diseases and gastric cancer. This review article covers this emerging human pathogen in terms of its phenotypic and genotypic characteristics, methods for culturing, its role in gastric pathogenicity, evidence involving its mode of transmission, difficulty in its isolation and detection methodology. In terms of transmission, both foodborne and waterborne pathways have been speculated as the mode of transmission for H. pylori as the patterns of the infection are consistent with those from fecal-oral and oral-oral transmission. Therefore, it is important to also evaluate methods for the detection of H. pylori from specifically food products and water. The detection of this pathogen has proved difficult since changes in cell morphology, metabolism and growth patterns occur when H. pylori is exposed to different environmental stimuli. The development of a viable but non-culturable coccoid (VNC) form is observed. These VNC forms do not undergo cellular division and cannot be cultured by traditional methods, increasing the difficulty in their detection. Since both viability and virulence in the VNC form of H. pylori are retained, the examination of food products and water for these forms is critical. Current methods include filtration, immuno-separation (IMS), polymerase chain reaction (PCR), probe hybridization, immuno-staining, autoradiography and ATP bioluminescence.

Probiotic capsules do not lower plasma lipids in young women and men.

Objective:To investigate the effect of probiotic capsules on plasma lipids.Design:A randomized, single-blinded, placebo-controlled, parallel-arm trial.Subjects:Fifty-five normocholesterolemic subjects ages 18–36 (33 premenopausal women and 22 men).Intervention:Each subject consumed either three probiotic capsules each containing a total of 109 colony-forming units Lactobacillus acidophilus and Bifidobacterium longum and 10–15 mg fructo-oligosaccharide or three placebo capsules daily for 2 months (men) or two menstrual cycles (women). Plasma lipids were measured before and following the intervention (during the early follicular phase for women).Results:Plasma concentrations of total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and triglyceride were not altered by consumption of probiotic or placebo capsules and were not different between treatment groups following the intervention.Conclusions:These results do not support a beneficial effect of Lactobacillus acidophilus strain DDS-1 and Bifidobacterium longum strain UABL-14 on plasma lipids in normocholesterolemic young women and men.Sponsorship:Supported by the Minnesota Agricultural Experiment Station and UAS Laboratories.

Consumption of Lactobacillus acidophilus and Bifidobacterium longum do not alter urinary equol excretion and plasma reproductive hormones in premenopausal women

Objective: To confirm the results of an earlier study showing premenopausal equol excretors to have hormone profiles associated with reduced breast cancer risk, and to investigate whether equol excretion status and plasma hormone concentrations can be influenced by consumption of probiotics.Design: A randomized, single-blinded, placebo-controlled, parallel-arm trial.Subjects: In all, 34 of the initially enrolled 37 subjects completed all requirements.Intervention: All subjects were followed for two full menstrual cycles and the first seven days of a third cycle. During menstrual cycle 1, plasma concentrations of estradiol (E2), estrone (E1), estrone-sulfate (E1-S), testosterone (T), androstenedione (A), dehydroepiandrosterone-sulfate (DHEA-S), and sex-hormone-binding globulin (SHBG) were measured on cycle day 2, 3, or 4, and urinary equol measured on day 7 after a 4-day soy challenge. Subjects then received either probiotic capsules (containing Lactobacillus acidophilus and Bifidobacterium longum) or placebo capsules through day 7 of menstrual cycle 3, at which time both the plasma hormone concentrations and the post-soy challenge urinary equol measurements were repeated.Results: During menstrual cycle 1, equol excretors and non-excretors were not significantly different with respect to subject characteristics, diet, or hormone concentrations. Significant inverse correlations were found between E2 and body mass index (BMI) (P=0.02), SHBG and BMI (P=0.01), DHEA-S and dietary fiber (P=0.04), and A and protein:carbohydrate ratio (P=0.02). Probiotic consumption failed to significantly alter equol excretor status or hormone concentrations during menstrual cycle 3, although there were trends towards decreased concentrations of T (P=0.14) and SHBG (P=0.10) in the probiotic group.Conclusions: We were unable to verify a previously reported finding of premenopausal equol excretors having plasma hormone concentrations different from those of nonexcretors. Furthermore, a 2-month intervention with probiotic capsules did not significantly alter equol excretion or plasma hormone concentrations.

Reduction of Escherichia coli O157: H7 viability on hard surfaces by treatment with a bacteriophage mixture

This study determined the effect of a previously characterized phage mixture, referred as BEC8 on enterohemorrhagic Escherichia coli (EHEC) O157:H7 strains applied on materials typically used in food processing surfaces. Sterile stainless steel chips (SSC), ceramic tile chips (CTC), and high density polyethylene chips (HDPEC) were used. Cultures of EHEC O157:H7 strains EK27, ATCC 43895, and 472 were combined, spot inoculated on surfaces, and dried. Chips were inoculated with 10(6), 10(5), and 10(4)CFU/chip, to obtain 1, 10 and 100 multiplicity of infection (MOI) values, respectively. Controls and BEC8 (approx. 10(6) PFU/chip) were applied on inoculated surfaces and incubated at 4, 12, 23, and 37 °C. EHEC survival was determined using standard plate count on tryptic soy agar. At 37 °C and 12 °C on SSC, no survivors were detected (detection limit 10CFU/chip) after BEC8 treatment at MOI of 100 after 10 min and at 23 °C after 1h on SSC. A similar result was obtained on CTC at 37 °C after 10 min, and after 1h at 23 °C. These results indicated that the phage cocktail was effective within an hour against low levels of the EHEC mixture at above room temperature on all 3 hard surfaces.

Effects of Dietary Arabinogalactan on Gastrointestinal and Blood Parameters in Healthy Human Subjects

Objectives: Arabinogalactan (AG) is a non-digestible soluble dietary fiber that resists hydrolytic enzyme action and enters the large bowel intact where it is fermented by resident microflora. To determine whether AG has similar physiological properties to other soluble dietary fibers, we examined the effect of 15 and 30 g per day of a commercially available AG from Western Larch on several gastrointestinal and blood parameters. Methods: Gastrointestinal parameters included fecal microflora, fecal enzyme activity, fecal short-chain fatty acids, fecal pH, fecal weight, transit time and bowel frequency. Blood parameters included total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides, Apo-A1, Apo-B, glucose and insulin. The study consisted of two three-week diet treatments with no washout period. Participants (n=20, 11 males, 9 females) consumed their usual diet in addition to 15 or 30 g AG in a beverage sweetened with aspartame as compared to their usual diet with the control beverage. Results: Significant increases in total fecal anaerobes were observed with 15 g (p=0.01) and 30 g AG (p=0.001). A significant increase (p=0.02) in Lactobacillus spp. was observed when subjects consumed AG for a total of six weeks regardless of dose. There were no significant changes in other microflora, fecal enzyme activity, transit time, frequency, fecal weight, fecal pH and short-chain fatty acids. Fecal ammonia levels decreased with 15 g (p=0.001) and 30 g (p=0.002) AG. No significant changes in blood lipids or blood insulin were observed. Conclusions: These data suggest that dietary AG is easily incorporated into the diet, well tolerated in subjects and has some positive effects on fecal chemistry.

Quenching and enhancement effects of ATP extractants, cleansers, and sanitizers on the detection of the ATP bioluminescence signal

Techniques for measuring ATP bioluminescence are being used widely as rapid methods for the assessment of the cleanliness of food-processing plants. Sanitizer or cleanser residues could present a potential problem in the use of these ATP bioluminescence techniques due to the degradation of the firefly luciferin-luciferase substrate-enzyme system by these cleaning chemicals. The objectives of this study were the evaluation of the quenching and enhancement effects on the detection of the ATP bioluminescence signal using various ATP extractants, commercial cleansers, and sanitizers, and the determination of the antimicrobial properties of different concentrations of cleansers and sanitizers on Escherichia coli OI57:H7, Listeria monocytogenes , Staphylococcus aureus , and Pseudomonasfragi . Extractants evaluated were benzalkonium chloride, Triton X-100,benzethonium chloride, cetylpyridinium chloride, and trichloroacetic acid. Cleansers evaluated were an alkaline foam and an acid foam. Also evaluated were a quaternary ammonium sanitizer, a d-limolene sanitizer, commercial sodium hypochlorite, and household bleach (sodium hypochlorite). The extractant cetylpyridinium chloride (0.0125%) did not have a statistically significant effect on the detection of the ATP bioluminescence signal at a 95% confidence level. A transition from enhancement to quenching as a concentration-dependent phenomenon was observed for the alkaline foam, acid foam, commercial sodiumhypochlorite,d-limolene,and household bleach. An enhancement effect that did not appear to be concentration-dependent was observed for the quaternary ammonium sanitizer. Antimicrobial disc assays demonstrated that in some cases the cleanser or sanitizer concentration was not effective against the bacteria, but enhanced or quenched the detection of the bioluminescence signal, leading to false-positive or false-negative results respectively.

Isolation and characterization of lytic bacteriophages against enterohaemorrhagic Escherichia coli

Aims:  The objective of this study was to isolate, identify and characterize a collection of lytic bacteriophages capable of infecting enterohaemorrhagic Escherichia coli (EHEC) serotypes.

Isolation and Partial Physiological Characterization of Commercial Strains of Bifidobacteria

The genus Bifidobacterium has been suggested to be capable of performing gastrointestinal modifications, providing nutritional value when added to the diet as a probiotic and having an inducing effect on the immune system by enhancing cytokine production. As a consequence, the dairy food industry is introducing bifidobacteria to such products as yogurt, flavored milk, and cottage cheese. The objectives of this project were to characterize isolates of bifidobacteria from commercial suppliers, to isolate and characterize bifidobacteria from dairy products, and to establish and compare their physiological characteristics. Physiological characterization was performed based on phenotypic characteristics, carbohydrate fermentation patterns, enzyme profiles, fructose-6-phosphate phosphoketolase (F6PPK) assays, and antibiotic sensitivities. The results demonstrated that commercial bifidobacteria strains and those strains isolated from dairy products were physiologically different. This demonstrates that some bifidobacteria present in dairy products may be mischaracterized when identifying their presence based solely on phenotypic characteristics. The difficulty in growth, rapid assessment, and isolation of bifidobacteria from a mixed culture in dairy products was evaluated in this study. X-α-Gal medium was selected as the most suitable for isolation of bifidobacteria from mixed culture products and modified lactobacilli MRS medium for growing pure isolates of bifidobacteria.