The objective of the present study was to construct a system that re-creates the conditions of fermentation and absorption of the human proximal colon. The model was constructed using a glass tube with an internal dialysis membrane tube. The food substrate was fed into the dialysis membrane three times a day simulating a typical human feeding. The substrate contained 58% carbohydrates, 35% proteins, 3% fiber, 3% starch, and 1% lipids on dry weight base, with 90% moisture. The inoculum was a fecal culture propagated in TSB. The intestinal absorption was simulated using a polyethylene glycol (PEG) solution running continuously outside the dialysis membrane. All microorganisms increased their counts after inoculation, and reached higher counts generally after substrate feed. The most important short chain fatty acids (SCFA: acetic, propionic and butyric acids) were analyzed, and their concentrations inside and outside the membrane were significantly different due to the extraction efficiency of the PEG solution. The greatest production occurred at 48 h. SCFA ratios showed that at the beginning, acetate was the predominant compound, but after 12 h the proportion of butyrate increased and the acetate was decreased. This SCFA production pattern is similar to that reported for the proximal colon in live systems. Continuous operation of the colon model for 48 h was enough to reveal the development of microorganisms and SCFA production. This model reproduced the conditions of the human proximal colon adequately and can be used to study the development of colonic microbiota.
Resistant starch (RS) stands out for its properties related to human health. In the digestive system it provides the benefits of dietary fiber and acts as a prebiotic. New sources of resistant starch are being investigated. The proximal composition, functional properties and microbiological quality of square banana starches (Musa balbisiana Colla) were determined. The fruits were harvested in plantations of Tabasco, Mexico, with degree of maturity type I. The flour was elaborated by drying in an oven. The extraction of the starches was carried out using a wet method and the resistant starches, by enzymatic method. The concentration of bacterial groups was quantified by the surface culture method. The solubility, swelling power and water absorption patterns were evaluated at 60, 70, 80 and 90 ºC. Products with low moisture content were obtained: flour (7.45 ± 0.28), native starch (9.28 ± 0.55) and sterilized starch (10.82 ± 0.10). In the protein content, the highest concentration was observed in the flour (4.44 ± 0.40), followed by the native starch (1.19 ± 0.04), RS2 (0.13 ± 0.01) and RS3 (0.19 ± 0.01). Functional properties are related to different factors, such as temperature, granule size, amylose content and type of resistant starch. RS3 presented the best functional properties and good microbiological quality. The native starch presented the highest microbial load. RS2 and the sterilized starch presented the lowest values of the functional properties.
Jalapeño pepper (Capsicum annuum L.) is a crop in protected natural areas of Tabasco, Mexico. Solar drying is a non-polluting energy that is applicable to food processing. This paper focuses on comparing the microbiological quality of dehydrated jalapeño peppers by means of three methods: direct solar (SD), electric stove (EE), and experimental solar dryer (SSE). SD drying was carried out in zinc sheet by conduction. The drying in EE was at a temperature of 70°C and the SSE has an internal temperature of 43 ° C ± 2 ° C. The dehydrated chiles were crushed in artisanal equipment, and the flour was stored in tightly closed glass containers at room temperature (22-28 ° C). The drying time was lower in the EE (7 h), followed by the SSE (8 h) and the SD (18 h). With EE, the lowest microbial load was obtained and with SD, the highest was obtained. The flour obtained with the SSE presented a concentration of microorganisms within the Mexican norms: total coliforms (25 CFU / g), Staphylococcus aureus (62 CFU / g), and aerobic mesophiles (57 CFU / g). Although the drying time and the microbial load were lower with the EE, the SSE allowed the elaboration of jalapeño pepper flour with the microbiological quality required for human consumption. Technified solar drying is a sustainable alternative for the dehydration of foods in tropical countries.
The content of lactic acid bacteria (LAB) is an important quality parameter in probiotic functional foods. Complex culture media formulated with natural additives are an alternative for their quantification. In this work we propose the use of orange, onion and jalapeño pepper juices, guava and noni pulps, as well as milk powder as ingredients of complex culture media for BAL quantification. The concentration of BAL recovered in the complex culture media and the commercial medium for lactobacilli De Man, Rogosa and Sharpe (MRS) were compared. No significant difference was found (P < 0.05) in BAL recovery between culture media made with orange juice (Log 9.33 ± 0.05 CFU/mL), guava pulp (Log 9.20 ± 0.10 CFU/mL), pulp noni (Log 9.12 ± 0.10 CFU/mL), milk powder (Log 9.10 ± 0.15 CFU/mL) and MRS (Log 9.20 ± 0.22 CFU/mL). However, the count was lower in the media added with onion and jalapeño pepper. Complex culture media are a simple, economical and quality alternative for the quantification of BAL in functional probiotic foods, such as fermented milk products and yogurt.
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