Ecuador is an agricultural country, which has an actual production of starch obtained from cassava. Tuber processing residues do not have an economic impact; for example, the cassava bagasse, only used for plant fertilization and animal feeding. This project aimed to study the influence of the fermentation variables (pH and agitation), on the lactic acid production. Enzymatic hydrolysis of cassava bagasse starch for the varieties INIAP 650 and INIAP 651 was performed using α-amylase and glucoamylase. Then, glucose was fermented by Lactobacillus leichmannii ATCC 7830 strains, varying conditions such as agitation (150 rpm and absence) and pH (4.5, 5.0, and 5.5). Finally, the determination of lactic acid was performed by potentiometric and FTIR analysis. Conversions of cassava bagasse to reduced sugars were 71.66 and 85.05 % for INIAP 650 and INIAP 651 varieties. The best lactic acid concentrations were 27.62 and 33.48 g/L, obtained at pH 5.5 and agitation, for INIAP 650 and INIAP 651 varieties. Qualitative analysis conducted by FTIR spectrophotometry confirmed the presence of lactic acid in the reacted products. Lactic acid production from cassava bagasse starch could contribute to the Manabí and Esmeraldas provinces of Ecuador's economic development.

The analysis of lysine represents a significant cost for the relevant food industries. The use of an enzymatic sensor would allow the reduction of time and cost of this analysis. An enzymatic sensor using lysine -α- oxidase (LOx) with a soluble enzyme sensor in combination with an oxygen electrode was optimized in this study to determine the lysine content in mozzarella cheese. Selective determination of lysine in mozzarella cheese is an indicator of quality and of ripening time. The potentiometric signal obtained due to oxygen depletion (consumed oxygen) during lysine oxidation was carried out during 100s in the soluble enzyme sensor. An optimal time sensor response to quantify the lysine content of 3.5s was calculated from the slope of reaction rates. The sensor was set at a potential of 0.6 mV. A positive linear relationship was found between consumed oxygen as a function of time (mg O₂/L × s) and lysine concentration in the range of 30–1,300 µM, with a coefficient of R² = 0.9968 for the soluble enzyme sensor. This system showed good specificity (K_M = 0.03 mM), which continued during eight weeks of cheese ripening time. The analysis of lysine with the soluble enzyme sensor in mozzarella cheese samples revealed very good agreement with the determination performed through standard HPLC methodology, which validated the use of this sensor as an alternative and more efficient technique to evaluate dairy products.

Background/Aims: This study investigates how pH levels affect the characteristics of biopolymer films manufactured from cassava peel starch. Cassava peel starch‘s abundance and biodegradability make it a promising candidate for sustainable packaging. The study seeks to improve film qualities such as thickness, density, moisture content, solubility, and optical properties by altering pH levels. Understanding these effects is critical for increasing the acceptability of cassava peel starch biopolymers in a variety of industrial applications, notably environmentally friendly packaging solutions. Methods: Starch extracted from cassava peel was used to produce films using the casting method at specified pH levels. The films were evaluated for thickness and density using classical methods. Moisture content was determined following the AOAC 930.15 (2000) protocol. Color analysis was conducted using the CIELab color space technique. Water solubility and solubility in acidic (HCl) and alkaline (NaOH) solutions were assessed through chemical solubility tests performed by gravimetry. Results: The study investigated how pH impacts biopolymer films manufactured from cassava peel starch. The film thickness varied greatly across pH levels, with pH 10.5 creating the thickest films (0.158 ± 0.012 mm) and pH 6.5 providing the thinnest (0.118 ± 0.015 mm). Density varied slightly, from 1.393 ± 0.122 g/cc to 1.551 ± 0.153 g/cc. Moisture content fluctuated significantly, affecting biodegradability. Color study indicated pH-dependent variations in transparency and opacity, with higher pH values resulting in larger color deviations (∆E). Water solubility remained constant, but NaOH solubility dropped with increasing pH, peaking at pH 7.5 (23.44 ± 2.82%). Conclusion: This work investigates the use of cassava peel starch for biopolymer synthesis at controlled pH levels. The findings demonstrate the material‘s practicality and provide critical insights for enhancing film qualities, particularly in a variety of industrial applications and environmentally friendly packaging solutions.

Background/Aims: The quantification of amino acids in the dairy industry is necessary for quality control and for the formulation of functional foods. Thus, the development of enzymatic biosensors requires a detailed study of enzyme kinetics. Parameters such as KM and Vmax are necessary to optimize the sensitivity and specificity of the biosensor. Methods: The enzyme immobilized on nylon and yucca bipolymer membranes was studied to evaluate possible interferences in the amperometric sensor. Results: The sensor developed based on enzyme kinetics proved to be a reliable, sensitive, and low-cost alternative for determining lysine in dairy products. Its performance, comparable to HPLC, together with its low environmental impact, positions it as a useful tool for quality control in the food industry. Conclusion: An enzymatic biosensor capable of quickly, accurately, and economically quantifying lysine in casein hydrolysates was developed. Its high sensitivity, enzymatic stability, and low environmental impact make it a viable and comparable alternative to HPLC for quality control in dairy products.