Liliana Serna Cock

Use of Enzymatic Biosensors as Quality Indices: A Synopsis of Present and Future Trends in The Food Industry

Biosensors are an important alternative in the food industry to ensure the quality and safety of products and process controls with effective, fast and economical methods. Their technology is based on a specific biological recognition element in combination with a transducer for signal processing. The use of enzymatic biosensor technology in food processing, quality control and on-line processes is promising compared to conventional analytical techniques, as it offers great advantages due to size, cost, specificity, fast response, precision and sensitivity. This article reviews the development and use of some enzyme biosensors in the food industry, describes the most important application areas and analyzes the current situation and future possibilities. In conclusion, enzymatic biosensors are a tool with broad application in the development of quality systems, risk analysis and critical control points, and the extent of their use in the food industry is still largely limited by the short lifetime of biosensors, in response to which the use of thermophilic enzymes has been proposed.

Producción Económica de Ácido Láctico Utilizando Residuos de Cosecha y Jugos de Caña de Azúcar (Saccharum officinarum L.)

Para la produccion fermentativa discontinua de acido lactico, se evaluaron como sustratos los jugos de cogollos y hojas (JCG) de la cana de azucar (Saccharum officinarum L.) y los jugos extraidos de esta cana, cosechada con quema (JCL) y sin quema (JCV). Las fermentaciones se realizaron anaerobicamente, a 32°C, con ajuste de pH a 6,0 y usando Lactococcus lactis subsp. lactis aislado de cultivos de la misma variedad. Para los sustratos mencionados y sus mezclas se estudio el efecto de la concentracion de azucares totales y de nitrogeno sobre la produccion de acido lactico (AL), la conversion de sustrato (CS), el rendimiento (Yp/s) y la productividad volumetrica (rp). Se obtuvieron concentraciones de acido lactico por encima de 70,19 g L-1, CS de 85,46%, Yp/s de 0,88 g g-1 y rp de 0,97 g L-1 h-1 con una concentracion de 90 g L-1 de azucar total usando una mezcla de JCG y JCV con adicion de 3% (p/v) de extracto de levadura. Aun sin adicion de extracto de levadura, estas mezclas presentaron muy buen comportamiento como sustrato de fermentacion acido lactica (AL: 26,16 g L-1, CS: 67,13%, Yp/s: 0,69 g g-1 y rp: 0,55 g L-1 h-1); este comportamiento se explica en parte por el mayor contenido en nitrogeno del JCG y del JCV, comparado con el JCL. El jugo extraido de las hojas y cogollos, mezclado con el jugo extraido de la cana cosechada sin quemar es una alternativa barata como materia prima para la produccion fermentativa de acido lactico.

The use of earthworm flour for lactic acid biomass production

The potential use of Californian red earthworm flour as a nitrogen source for the production of lactic biomass was assessed. Three fermentation substrates, earthworm flour (EF), earthworm flour + yeast extract (EF + YE) and a commercial substrate MRS (control) were used. The substrates were formulated using 60 g L -1 of glucose as the carbon source and 34 gL -1 of earthworm flour as the nitrogen source. Weissella confusa was used as lactic acid bacterium. Nine batch fermentations were performed at 32°C and 100 rpm for 4 h, and the kinetics of the biomass concentration, lactic acid concentration and substrate consumption were compared. No differences were observed in the biomass concentration of the EF and EF + YE substrates, and final concentrations of 1.36 and 1.47 g L -1 were obtained, respectively. The lactic acid concentration did not differ significantly between EF + YE and the commercial substrate, and values of 4.79 and 4.33 g L-1 were obtained, respectively. These results suggest that earthworm flour can be a low-cost alternative for lactic acid biomass production. Keywords: Earthworm flour, Weissella confusa , lactic acid bacteria African Journal of Biotechnology Vol. 12(40), pp. 5962-5967

Double emulsion and complex coacervation in stevia encapsulation

En Colombia el consumo de mango verde fresco (tambien conocido como mango “biche”) es popular, y se consume con zumo de limon, sal y miel. Sin embargo, su alto contenido de humedad y alta actividad de agua hace que el mango sea un fruto altamente perecedero, por lo que requiere alternativas de procesamiento. La deshidratacion osmotica (OD) es una interesante alternative para la conservacion de mango. En OD se utilizan tradicionalmente soluciones binarias (solute + agua) y soluciones ternarias (2 solutos + agua), sin embargo, puede removerse mayor cantidad de agua utilizando soluciones ternarias, las cuales permiten mejorar las propiedades organolepticas de productos deshidratados. Objetivos: Evaluar las cineticas de perdida de agua (WL), ganancia de solutos (SG), reduccion de peso (WR), actividad de agua (aw) y volumen (coeficiente de encogimiento, SC) en muestras de mango verde (Mangifera indica L. Filipino variety) deshidratadas osmoticamente (OD). Adicionalmente, calcular la difusividad (D_ef) del agua y de solutos, en los distintos tratamientos. Metodos: Se usaron mangos verdes con escala de madurez cero. En la OD se Se usaron soluciones ternarias compuestas por sacarosa (40%) y NaCl al 3, 6 y 9%. Como tratamiento control se uso una solucion binaria de sacarosa mas agua. En el proceso osmotico las muestras fueron tomadas a diferentes tiempos de OD (15, 30, 60, 90, 180, 240, and 300 m). Resultados: Los resultados mostraron que al incrementar la concentracion de NaCl, las WL fueron mas rapidas, la aw y el SC fueron menores y las D_ef de agua y solutos mayores. Las muestras deshidratadas con la maxima concentracion de solutos (40-9%), alcanzaron las mayores WL, SG y WR con valores de 59.82, 13.10 y 46.68%, respectivamente. Los coeficientes Defw and Defs mostraron orden de magnitude de 10-10 m2/s, valor que se encuentra en el intervalo para alimentos deshidratados. Conclusiones: Esta investigacion mostro que soluciones binarias (sacarosa + agua) y ternarias (NaCl + sacarosa + agua) son adecuadas para deshidratar mango verde, sin embargo, las soluciones ternarias fueron mas efectivas.

Cambios en propiedades mecanicas durante la deshidratación osmotica de pitahaya amarilla

Fruits such as yellow pitahaya exhibit changes in their mechanical properties during osmotic dehydration (OD). The knowledge of these mechanical properties is useful for the analysis of the quality and/or stability of the food. There was evaluated the influence of the time of osmotic dehydration, the level of pressure (atmospheric pressure and vacuum pulse) and the sucrose concentration of the osmotic solution (SO) (45 and 65°Brix) on the mechanical properties of slices of pitahaya. The vacuum pulse was 5 kPa for 5 min. Fresh and dehydrated samples were subjected to uniaxial compression tests until rupture; Three mechanical parameters were evaluated (fracture stress, fracture strain and modulus of elasticity). The results showed that the fracture stress and modulus of elasticity decreased significantly with OD time and vacuum pulse application, while increasing with increasing sucrose concentration. The fracture strain was increased with the OD time and with the vacuum pulse. These results indicate that the yellow pitahaya retains more firmness with atmospheric pressure and with 65°Brix with respect to the treatments with application of the empty pulse.