Lipases and esterases are biocatalysts used at the laboratory and industrial level. To obtain the maximum yield in a bioprocess, it is important to measure key variables, such as enzymatic activity. The conventional method for monitoring hydrolytic activity is to take out a sample from the bioreactor to be analyzed off-line at the laboratory. The disadvantage of this approach is the long time required to recover the information from the process, hindering the possibility to develop control systems. New strategies to monitor lipase/esterase activity are necessary. In this context and in the first approach, we proposed a lab-made sequential injection analysis system to analyze off-line samples from shake flasks. Lipase/esterase activity was determined using p-nitrophenyl butyrate as the substrate. The sequential injection analysis allowed us to measure the hydrolytic activity from a sample without dilution in a linear range from 0.05–1.60 U/mL, with the capability to reach sample dilutions up to 1000 times, a sampling frequency of five samples/h, with a kinetic reaction of 5 min and a relative standard deviation of 8.75%. The results are promising to monitor lipase/esterase activity in real time, in which optimization and control strategies can be designed.

Overweight and obesity promote diabetes and heart disease onset. Triglycerides are key biomarkers for cardiovascular disease, strokes, and other health issues. Scientists have devised methods and instruments for the detection of these molecules in liquid samples. In this study, an enzymatic biosensor was developed using an Arduino-based microfluidic platform, wherein a lipolytic enzyme was immobilized on an ethylene-vinyl acetate polymer through physical adsorption. This low-cost optical biosensor employed a spectrophotometric transducer and was assessed in liquid samples to indirectly detect triglycerides and fatty acids using p-nitrophenol as an indicator. The average triglyceride level detected in the conducted experiments was 47.727 mg/dL. The biosensor exhibited a percentage of recovery of 81.12% and a variation coefficient of 0.791%. Furthermore, the biosensor demonstrated the ability to detect triglyceride levels without the need for sample dilution, ranging from 7.6741 mg/dL to 58.835 mg/dL. This study successfully developed an efficient and affordable enzymatic biosensor prototype for triglyceride and fatty acid detection. The lipolytic enzyme immobilization on the polymer substrate provided a stable and reproducible detection system, rendering this biosensor an exciting option for the detection of these molecules.

The yeast Kluyveromyces marxianus has shown the potential to produce $\beta$-fructofuranosidases, which are enzymes capable of hydrolyzing $\beta$-fructofuranosides links of fructans to obtain fructooligosaccharides. The thriving market for fructose syrup and the quality standards imposed by food and pharmaceutical industries have generated an increased search for improved, monitored, and controlled production processes. Monitoring $\beta$-fructofuranosidase activity in a bioprocess requires the use of adequate sensors and the processing of information using efficient software algorithms; nevertheless, currently, such a sensor does not exist for this purpose. In this contribution, a sequential injection analysis system (SIA) developed in our laboratory was adapted to monitor at-line $\beta$-fructofuranosidase activity produced by the yeast K. marxianus. Samples were taken out automatically from the bioreactor and analyzed using 3,5-dinitrosalicylic (DNS). An algorithm was designed to operate the overall components of the lab-made SIA system. The enzymatic activity error obtained with the automatic SIA compared to the off-line laboratory determinations varied from 0.07% at high enzyme concentrations to 20.39% at low $\beta$-fructofuranosidase activity. Further development is required to improve the performance of the lab-made SIA system; nevertheless, such a device must be considered as a potential method for monitoring $\beta$-fructofuranosidase activity in real time.

In the present study, a novel laccase from ascomycete Gliomastix murorum was produced in agro-industrial wastes and entrapped in galactomannan beads for Reactive Blue 2 (Rb-2) decolorization. The maximum laccase production in agave bagasse-based medium occurred at 72 h (1798.6 UL⁻¹). Entrapped laccase decolorized ˃80% of 0.5 mM Rb-2 in 2 h without the addition of redox mediator. K_m for Rb-2 substrate was 1.42 mM, with a V_max of 1.19 µmol min⁻¹ for entrapped laccase. Galactomannan matrices produce stability to acid pH (2–5) and temperatures from 20–70 °C. Reusability assays showed that entrapped laccase could retain efficient Rb-2 decolorization of ˃80% six times. In general, galactomannan used for entrapment of laccase provides economic advantages in large-scale wastewater treatment due to its natural origin and efficient results.

La leche cruda de vaca se utiliza como materia prima sin pasteurizar para la elaboración de productos artesanales; sin embargo, es necesario analizar su calidad antes de su transformación al producto final. El objetivo del presente estudio fue evaluar los parámetros de calidad de leche cruda de una Cooperativa de productores del municipio de Tepatitlán de Morelos, Jalisco, utilizada para elaborar productos artesanales con respecto a los límites fisicoquímicos y microbiológicos establecidos en la normatividad mexicana. Los factores de estudio del presente trabajo fueron tipo de ordeño y tratamiento que recibe la leche. El análisis de la calidad de las muestras recolectadas se efectuó acorde a metodologías oficiales. Respecto a la calidad microbiológica, los resultados de células somáticas, bacterias mesofílicas y organismos coliformes totales demostraron que la mayoría de las muestras no cumplen con los criterios establecidos. Contrariamente, los resultados del análisis fisicoquímico de la leche mostraron que el contenido de proteína, grasa, lactosa y sólidos no grasos se encuentran dentro de las especificaciones que dicta la normatividad. Los resultados reflejan la mala calidad microbiológica de la leche utilizada para la elaboración de productos artesanales; siendo esto la consecuencia de prácticas higiénicas deficientes durante la ordeña, almacenamiento y transporte.