Doctor of Philosophy, The Ohio State University, 2022, Food Science and Technology

Waste streams from the food industry have been associated with severe environmental pollution and an economic burden for producers. The Food and Agricultural Organization from the United Nations has stated that one-third of the global food chain production ends up as food waste. The dairy and fish industry has significant roles in producing waste streams that threaten the ecosystem due to their high biological and chemical oxygen demand. The by-products from both industries have shown several complications for its proper treatment of disposal. Therefore, science-based approaches that can handle the treatment more efficiently or, otherwise, transform them to add value and include them as part of other foods. The increasing demand for acidified and fresh-like dairy products has made the handling of acid whey a disposal burden for this industry. Acid whey is the milk serum left after the removal of caseins after fermentation and acidification. On the other hand, the most valuable part of fisheries is the fillet that only represents 40-45% of a fish; this value means that more than 50% of this food chain becomes waste. However, both waste streams are considered nutrient-dense co-products with potential complementary nutritional advantages suitable for biotechnological technologies and valuable products' production. In this work, we hypothesized that under appropriate conditions, a semi-controlled fermentation of the mix of acid whey and minced fish waste can break down the complex proteins from fish; a close follows up to understand the microbiome and chemical changes would lead to a safe and nutritionally bioavailable product. To this end, the first objective was to find the optimum conditions and materials ratios that would deliver the best proteolysis, including the addition of a starter culture and a simple carbohydrate source. Additionally, the innate microbiota from the co-products and changes during the fermentation was closely monitored using 16S-v4 rRNA a (open full item for complete abstract)

Committee: Rafael Jimenez-Flores (Advisor) Subjects: Food Science

Master of Science, The Ohio State University, 2020, Food Science and Technology

Milk phospholipids (MPLs) are valuable dairy components known for various health benefits, like reducing gastrointestinal infections and supporting neurological development. They are used as functional ingredients for food application and human consumption. Meanwhile, lactic acid bacteria (LAB) are also associated with beneficial effects on human health. They are commonly used in fermented dairy products, and many of them are regarded as probiotics. The possibility of using MPLs and LAB as a combination has great potential benefit and has shown some synergistic effects on the delivery of both ingredients. Little is known about the direct impact of MPLs on LAB, which contributes to the determination of MPLs supplementation strategies and LAB culture selection. Our first objective was to test the influence of MPLs on the growth and cryotolerance of LAB in MRS and acid whey-based dairy (AW) media. We screened 134 strains in our collection and selected 13 LAB strains using 0.5% MPLs supplemented modified minimal medium (MM) and another 14 strains using the AW medium. The growth curves of those 13 LAB in MRS and 0.5% MPLs supplemented MRS media were compared. The cell viability counts and acidification ability of those 14 strains cultivated in AW and 0.5% MPLs supplemented acid whey-based (AWM) media were evaluated using the plate counting method and skim milk fermentation test before and after three cycles of freeze-thawing treatment. We hypothesized that the addition of MPLs would impact the growth of LAB differently in diverse media, and MPLs supplementation could modify the cryotolerance of LAB. Results indicated that the addition of 0.5% MPLs showed a strong inhibitory impact on the growth of LAB in the MRS medium while promoting the growth and enhancing the cryotolerance of LAB significantly in the AWM medium. The second objective was to investigate the adhesion or interaction between MPLs and LAB using the sucrose gradient centrifugation test and further analyze t (open full item for complete abstract)

Committee: Rafael Jimenez-Flores (Advisor); Ahmed Yousef (Committee Member); Zhongtang Yu (Committee Member) Subjects: Food Science

Master of Science, The Ohio State University, 1971, Graduate School

Committee: Not Provided (Other) Subjects:

Doctor of Philosophy, The Ohio State University, 2024, Food Science and Technology

This dissertation investigates the enzymatic parameters of a β-galactosidase derived from the probiotic candidate, Lactobacillus helveticus OSU-PECh-4A (Lb. helveticus), with a focus on its potential for galacto-oligosaccharide (GOS) production. β-galactosidase is a hydrolytic enzyme that catalyzes the breakdown of lactose into its simpler sugar, glucose, and galactose. Simultaneously with lactose hydrolysis and under specific conditions, β-galactosidase can also produce highly demanded prebiotics known as galacto-oligosaccharides (GOS). In this dissertation, a thermostable β-galactosidase from Lb. helveticus has been isolated through diafiltration and size-exclusion chromatography and characterized through enzymatic assay and differential scanning fluorimetry (DSF). The isolated enzyme consists of a heterodimer with a molecular mass of 110 kDa, with a small and large subunit of 36 kDa and 74 kDa, respectively. The Km and Vmax values for lactose hydrolysis were 29.87 ± 1.05 mM and 1.88 ± 0.02 μmol D-glucose released per min per mg of protein, respectively. The enzyme is stable under a wide range of pH and high temperatures in terms of activity (≥ 40 °C). Once characterized, the enzyme capacity to produce GOS was evaluated through a 2x2 factorial design using substrate concentration and temperature as variables. The GOS produced were quantified and identified using high-performance liquid chromatography coupled with a charged aerosol detector (HPLC-CAD) and liquid chromatography with electrospray ionization mass spectroscopy (LC-ESI-MS/MS), respectively. To provide a perspective of the many possible applications of the enzyme, the enzyme's capacity to use different sugar acceptors to produce fucose-containing GOS was also evaluated by comparison. A maximum GOS yield of 12% was obtained at an initial lactose concentration of 200 g/L under 45 °C for 12 h. The GOS mixture consisted of 82% GOS, from which 6'galactosyl-lactose (trisaccharide), lactulose (disaccharides) (open full item for complete abstract)

Committee: Rafael Jiménez-Flores (Advisor); Valente Álvarez (Committee Member); Monica Giusti (Committee Member); Osvaldo Campanella (Committee Member) Subjects: Food Science

Master of Science, The Ohio State University, 2021, Food Science and Technology

Lactic acid bacteria (LAB) are rarely found in single species in naturally occurring food fermentations such as yoghurt, kefir wine, etc. This is because synergistic microbial communities promote positive interactions between species thus promoting better growth, metabolite regulation, and antimicrobials production. These positive interactions can be facilitated by nutrient and metabolite exchange, changes in the extracellular environment (pH, ionic strength), quorum sensing, or the exchange of enzymes. In general, properties of LAB in monocultures have been extensively studied in different growth media, however, synthetic co-cultures are less explored and are gaining increasing research attention. Enzymatic activities such as proteolytic, lipolytic, and β-galactosidase can be correlated to nutrient exchange between LAB, flavor, and texture in food fermentations. Changes in these enzymatic and antimicrobial activities in co-cultures, and their impact on the growth of individual species remain unexplored. Here in this study, we present a comparison of growth of LAB in multiple co-cultures (consortia) over 20 h of growth, while also tracking the enzymatic and antimicrobial activities (bioactivities) of the co-cultures over time. Lactobacillus plantarum OSU-PECh-BB (Lp), Lactobacillus reuteri OSU-PECh-48 (Lr), and Pediococcus acidilactici OSU-PECh-3A (Pa) were chosen for this study and seven combinations were made from them (Lr, Lp, Pa, Lr-Lp, Lp-Pa, Lr-Pa, Lr-Lp-Pa). The growth of individual species was tracked in every combination using iv Real Time-qPCR and was compared across the combinations. Case of commensalism was observed between Lr and Lp, where Lp grew in higher counts with no impact on Lr. This result was attributed to the high proteolytic activity of Lr during the initial stages of growth. On the other hand, amensalism was observed between Lp and Pa, where Lp grew in significantly lower counts as compared to its monocu (open full item for complete abstract)

Committee: Rafael Jiménez-Flores (Advisor); Matthias Klein (Committee Member); Osvaldo Campanella (Committee Member) Subjects: Food Science; Microbiology; Molecular Biology

Master of Science, The Ohio State University, 2020, Food Science and Technology

Kefir is a fermented dairy beverage that has been shown to successfully treat recurrent Clostridioides difficile infection (CDI) when consumed in conjunction with antibiotic treatment. Unfortunately, kefir has limited patient acceptance due to its strong acidic and fermented flavors produced during fermentation. To improve the flavor of kefir, further processing could be utilized, such as high heat spray drying, which can reduce undesirable volatile organic compounds (VOCs). To protect live microorganisms from high heat, encapsulating agents may be added to the mixture. In this study, the effect of spray drying with and without an encapsulating agent on commercial kefir's water activity, moisture content, VOCs concentration, microbial viability and activity, microstructure, and sensory quality was analyzed. Kefir was spray dried in the pilot plant either without an encapsulating agent, with whey permeate, or with whey protein isolate. Water activity and moisture content of powder samples were obtained; volatile compounds concentration was measured using selected-ion flow-tube mass spectrometry (SIFT-MS); microbial viability was assessed by enumeration on selective media for Lactobacillus species and Lactococcus species, and bacteria were identified by 16S ribosomal DNA (rDNA) sequencing; microbial activity was assessed by inoculating kefir into milk and measuring change in pH over time; microstructure was examined using scanning electron microscopy (SEM) images, and sensory quality was determined by untrained panelists ranking samples and answering acceptability/likeability questions on kefir attributes. All three spray-dried kefir powder samples had water activity below 0.25 and water content below 5%, indicating high storage stability products. The total concentration for 29 VOCs in all spray-dried products was reduced significantly, with spray-dried kefir without encapsulating agent having the highest reduction of 61.2%, followed by kefir with whey permea (open full item for complete abstract)

Committee: Valente Alvarez (Advisor); Rafael Jimenez-Flores (Committee Member); Ahmed Yousef (Committee Member) Subjects: Food Science

Master of Science, The Ohio State University, 2019, Food Science and Technology

Buttermilk is rich in milk fat globule membrane (MFGM), which consist of a well-defined group of milk phospholipids (MP). MP play an important role in brain and nervous system development. However, intact MP are also known for its low absorption in the intestine when compared with glycerolipids. Lactic acid bacteria (LAB) is one of the most common bacteria used in dairy products. Many of the LAB are beneficial for health, improving gut function, and regulating immune response. Moreover, the metabolites: the lipases and proteases produced by them can hydrolysate lipids and proteins, which can lead to better absorption of nutrients. Studies showed that metabolites produced by LAB are associated with increased absorption of sphingomyelin and potentially all the MP. The hypothesis is that LAB with lipolytic activity resulting from buttermilk fermentation with MP enriched can increase the presence of enzymes that can modify phospholipid and produce phospholipid hydrolysates with presumptive higher absorption. Bacteria characterization, classification and isolation were performed from the collection at OSU in Jimenez' laboratory using 16S rDNA sequencing. Quantitative lipolysis and proteolytic activity were tested using α -naphthyl acetate, 4-nitrophenyl derivatives of C2-C14 and azocasien. Seven promising strains, one negative control, Staphylococcus warneri, and one positive control, Enterococcus faecalis were tested to screen their functional characteristics. Testing includes resistance to digestion including resisting low pH and bile salts, high values in auto-aggregation and hydrophobicity, and antimicrobial activity against indicator pathogenic strains: Escherichia coli ATCC 25922 and Listeria innocua ATCC 51742. Furthermore, antibiotics resistance was tested using eight antibiotics: chloramphenicol, vancomycin, tetracycline, erythromycin, ampicillin, kanamycin, clindamycin, and streptomycin. Virulence factors (agg, ace, asa1, fbp, cbp, mazm, eFaA, hdc, odc, tdc, ge (open full item for complete abstract)

Committee: Rafael Jimenez-Flores (Advisor); Sheila Jacobi (Committee Member); Ahmed Yousef (Committee Member); Hua Wang (Committee Member) Subjects: Food Science

Master of Science, The Ohio State University, 2018, Comparative and Veterinary Medicine

Human noroviruses (HuNoVs) are responsible for more than 95% of the non-bacterial acute gastroenteritis epidemics in the world. The CDC estimates that every year 21 million individuals suffer from HuNoV-induced gastroenteritis in the U.S. Currently, there is no FDA-approved vaccine for HuNoVs. Development of an effective vaccine has been seriously hampered by the lack of an efficient cell culture system for HuNoVs and a suitable small animal model. The goal of this study is to develop lactic acid bacteria (LAB) as a vector to deliver HuNoV antigen. To do this, a LAB bacteria strain (Lactococcus lactis) carrying VP1 gene of a HuNoV GII.4 virus (LAB-VP1) was constructed. It was found that HuNoV VP1 protein was highly expressed by LAB vector. Subsequently, a novel microencapsulation technology was developed to enhance the stability of LABs in low and high pH environments. To test whether LAB-based HuNoV vaccine is immunogenic, 4-day-old gnotobiotic piglets were orally inoculated with various doses of LAB-VP1 either with or without microencapsulation. It was found that LABs were persistent in the small intestine of piglets and shed in pig feces for at least 25 days post inoculation. Live LABs or LAB DNA were found in mesenteric lymph nodes and spleen tissue in LAB-VP1 inoculated groups. HuNoV-specific IgG and IgA were detectable in serum and feces at day 13 post-inoculation, respectively, and further increased at late time points. After challenge with HuNoV GII.4 strain, a large amount of HuNoV antigens were observed in the duodenum, jejunum, and ileum sections of the intestine in the LAB control group. In contrast, significantly less or no HuNoV antigens were detected in the LAB-VP1 immunized groups. Collectively, these results demonstrate that LAB-based HuNoV vaccine induces protective immunity in gnotobiotic piglets.

Committee: Jianrong Li (Advisor); Prosper Boyaka (Committee Member); Melvin Pascall (Committee Member) Subjects: Microbiology; Virology

Doctor of Philosophy, The Ohio State University, 1970, Graduate School

Committee: Not Provided (Other) Subjects: Agriculture

Doctor of Philosophy, The Ohio State University, 1960, Graduate School

Committee: Not Provided (Other) Subjects: Biology