Microbial Composition and Diversity of High-demand Street-vended Foods in Ecuador.

Developing countries such as Ecuador carry a heavy food safety burden but reports on the microbiological quality of their foods are scarce. In this investigation, the microbial diversity of 10 high-risk and mass-consumption street-vended foods including bolones, encebollado, food dressings, ceviche, chopped fruits, fruit juices, fruit salads, cheese, raw chicken, and ground beef in Quito, Guayaquil, and Cuenca, three major population centers in Ecuador, were evaluated using 16S rRNA gene High Throughput Sequencing. In total, 1,840 amplicon sequence variants (ASVs) were classified into 23 phyla, 253 families, 645 genera, and 829 species. In the tested food samples, Proteobacteria and Firmicutes were the most abundant phyla accounting for 97.41% of relative abundance (RA). At genus level, 10 dominant genera were identified: Acinetobacter (12.61% RA), Lactococcus (12.08% RA), Vibrio (8.23% RA), Weissella (7.43% RA), Aeromonas (6.18% RA), Photobacterium (6.32% RA), Pseudomonas (3.92% RA), Leuconostoc (3.51% RA), Klebsiella (3.49% RA), and Cupriavidus (2.86% RA). The highest microbial diversity indices were found in raw chicken, encebollados, fruit salads, and fruit juices from Guayaquil and Cuenca. From sampled foods, 29 species were classified as food spoilage bacteria and 24 as opportunistic pathogenic bacteria. Two groups associated with human diseases were identified, including 11 enteric species and 26 species of fecal bacteria. The occurrence of recognized and opportunistic pathogenic bacteria, as well as enteric and fecal microorganisms, in the street-vended foods indicated extensive risks for the consumers' health. This study demonstrated the application of culture-independent amplicon sequencing in providing a more comprehensive view of microbial safety for street-vended food, which could be a useful tool to facilitate the control of foodborne diseases.

Traditional Fermented Foods from Ecuador: A Review with a Focus on Microbial Diversity.

The development of early civilizations was greatly associated with populations' ability to exploit natural resources. The development of methods for food preservation was one of the pillars for the economy of early societies. In Ecuador, food fermentation significantly contributed to social advances and fermented foods were considered exclusive to the elite or for religious ceremonies. With the advancement of the scientific research on bioprocesses, together with the implementation of novel sequencing tools for the accurate identification of microorganisms, potential health benefits and the formation of flavor and aroma compounds in fermented foods are progressively being described. This review focuses on describing traditional fermented foods from Ecuador, including cacao and coffee as well as less popular fermented foods. It is important to provide new knowledge associated with nutritional and health benefits of the traditional fermented foods.

Microbiological Quality of High-Demand Food from Three Major Cities in Ecuador.

ABSTRACT: Bacterial foodborne diseases are among the most important public health issues worldwide, but in Ecuador, reports on the microbiological quality of food are scarce. In this cross-sectional study, 450 samples of high-demand Ecuadorian food, including bolon, encebollado, sauces, ceviche, fruit, fruit juice, fruit salad, cheese, raw chicken, and ground beef, were collected from popular street markets in the cities of Guayaquil, Quito, and Cuenca. Populations of total aerobic mesophilic bacteria, total coliforms, fecal coliforms, Escherichia coli, Salmonella enterica, and Listeria monocytogenes were examined on composited samples by plate count following the local regulations (Norma Tecnica Ecuatoriana, Instituto Ecuatoriano de Normalización) for each kind of food. The individual and interaction effects of the city and food type on the levels of each bacterial group were assessed by two-way analysis of variance. Selected colonies from each culture were identified using Biolog OmniLog ID and sequencing of the V3 to V4 region on the 16S rRNA gene. Average total aerobic mesophilic bacteria, total coliform, fecal coliform, and E. coli levels were 5.10 ± 0.12, 2.50 ± 0.16, 1.09 ± 0.12, and 0.83 ± 0.12 log CFU/g or mL, respectively, with significant variations among the cities. The prevalence of Salmonella in chicken and sauces and L. monocytogenes in cheese and fruit salad was greater than 20%. Opportunistic pathogens including Klebsiella pneumoniae, Staphylococcus sciuri, and Enterococcus spp. were frequently identified in the samples from all three cities. High prevalence of spoilage microorganisms such as Bacillus amyloliquefaciens and biocontrol bacteria such as Lactococcus lactis was also observed. This is the first report on the microbiological quality of food from Ecuador.

Metabolomics in food science.

Metabolomics, the newest member of the omics techniques, has become an important tool in agriculture, pharmacy, and environmental sciences. Advances in compound extraction, separation, detection, identification, and data analysis have allowed metabolomics applications in food sciences including food processing, quality, and safety. This chapter discusses recent advances and applications of metabolomics in food science.

GC-MS based metabolomics for rapid simultaneous detection of Escherichia coli O157:H7, Salmonella Typhimurium, Salmonella Muenchen, and Salmonella Hartford in ground beef and chicken.

A metabolomic-based method for rapid detection of Escherichia coli O157:H7, Salmonella Hartford, Salmonella Typhimurium, and Salmonella Muenchen in nonselective media was developed. All pathogenic bacteria were grown in tryptic soy broth (TSB) at 37 °C followed by metabolite quantification at 2-h intervals for 24 h. Results were compared with the metabolite profiles similarly obtained with E. coli K12, Pseudomonas aeruginosa, Staphylococcus aureus, Saccharomyces cereviseae, and Aspergillus oryzae grown individually or as a cocktail under the same conditions. Principal component analysis (PCAS) discriminated pathogenic microorganisms grown in TSB. Metabolites responsible of PCAS classification were dextrose, cadaverine, the aminoacids L-histidine, glycine, and L-tyrosine, as well as the volatiles 1-octanol, 1-propanol, 1butanol, 2-ethyl-1-hexanol, and 2,5-dimethyl-pyrazine. Partial least square (PLS) models based on the overall metabolite profile of each bacteria were able to detect the presence of Escherichia coli O157:H7 and Salmonella spp. at levels of approximately 7 ± 2 CFU/25 g of ground beef and chicken within 18 h.

GC-MS analysis of headspace and liquid extracts for metabolomic differentiation of citrus Huanglongbing and zinc deficiency in leaves of 'Valencia' sweet orange from commercial groves.

INTRODUCTION: Citrus Huanglongbing (HLB) is considered the most destructive citrus disease worldwide. Symptoms-based detection of HLB is difficult due to similarities with zinc deficiency. OBJECTIVE: To find metabolic differences between leaves from HLB-infected, zinc-deficient, and healthy 'Valencia' orange trees by using GC-MS based metabolomics. METHODOLOGY: Analysis based on GC-MS methods for untargeted metabolite analysis of citrus leaves was developed and optimized. Sample extracts from healthy, zinc deficient, or HLB-infected sweet orange leaves were submitted to headspace solid phase micro-extraction (SPME) and derivatization treatments prior to GC-MS analysis. RESULTS: Principal components analysis achieved correct classification of all the derivatized liquid extracts. Analysis of variance revealed 6 possible biomarkers for HLB, of which 5 were identified as proline, ß-elemene, (-)trans- caryophyllene, and α-humulene. Significant (P < 0.05) differences in oxo-butanedioic acid, arabitol, and neo-inositol were exclusively detected in samples from plants with zinc deficiency. Levels of isocaryophyllen, α-selinene, ß-selinene, and fructose were significantly (P < 0.05) different in healthy leaves only. CONCLUSION: Results suggest the potential of using identified HLB biomarkers for rapid differentiation of HLB from zinc deficiency.

Untargeted metabolite analysis of healthy and Huanglongbing-infected orange leaves by CE-DAD.

Huanglongbing (HLB) is considered the most destructive bacterial citrus disease worldwide. Early detection of HLB is crucial for minimizing its spread. CE was used for the discovery of potential biomarkers for HLB. Optimization of extraction and separation allowed resolving 24 compounds of which 6 were present in significantly higher (p<0.05) concentrations in HLB-infected samples collected monthly for 6 months during the 2007-2008 season. Three of these compounds were identified by mobility and UV spectra as hesperidin, naringenin, and quercetin with mean increase in concentration of 154, 555, and 467%, respectively, above that in healthy leaves. Results support the potential of CE-DAD for untargeted plant metabolomic analysis. CZE, NACE, and MEEKC were compared for metabolic differentiation of healthy and HLB-infected citrus leaves. CZE in a semi-aqueous BGE solution consisting of 8.5 mM of sodium borate (pH 9.3), 15% ACN, and 9% 1-butanol yielded the best peak separation with detection at 190 nm.