The applications of microalgae are being increasingly explored, as they have a high rate of cell duplication and accumulation of lipids, ranging from 20-50% of their dry weight, reaching up to 80% under appropriate conditions. Their cultivation in artificial conditions has also increased, which has made it important to explore different microalga quantification methods and evaluate its growth kinetics. For algal quantification, it appears that both quantification methods by direct counting in a Neubauer chamber (density) and indirect counting methods such as reading in spectrophotometry (optical density) and dry weight (biomass), are important to validate the results quantification. The objective of this study was to verify the existence of a functional relationship between the variables used to quantify the microalgae Chlorella sorokiniana. For this purpose, linear regression analysis was applied to the variables of cell density, optical density, and dry biomass that were obtained by cultivating the microalgae at different concentrations. Using the equations generated from the regression analysis in Chlorella sorokiniana, it was possible to obtain ​​cell density values between 3 and 3.8 × 106 mL-1 and dry biomass values between 0.1 and 4.3 mg.mL-1 from the optical density values acquired using spectrophotometry with extreme precision, and this method was found to be highly feasible.

Edible coating are commonly used as they minimize post-harvest losses and extend the shelf life of fruits. Therefore, in this study, analyzed the effect of edible coatings containing gibberellic acid (GA₃) on the shelf life of tomatoes (Solanum lycopersicum L.). Tomatoes were divided into six groups: Uncoated (CT); coating with 75 and 100 mg L^-1 of GA₃ solubilized in water without adding pectin (A75 and A100, respectively); coating with 75 and 100 mg L^-1 of GA₃ with added pectin (P75 and P100, respectively); coating pectin only (PEC). Pectin-based coatings (PEC, P75, and P100) were produced by solubilizing pectin (3%) in water, followed by adding different concentrations of GA3.Treatments A75 and A100 were prepared with distilled water and 75 and 100 mg L^-1 GA₃. Tomatoes (turning stage) were immersed in the solutions for 3 min, dried at room temperature, and stored at 12 °C (90% RH). The pH, titratable acidity, soluble solids, color and weight loss were analyzed every four days for 32 days, and the firmness of the tomatoes was analyzed every seven days for 35 days. Coatings with GA₃ maintained firmness, delayed weight loss, and decreased acidity, pH, sugar content, and color changes. Pectin-based coatings (P75, P100) were the most effective in delaying weight loss. The application of GA₃ associated with pectin-based coatings delayed the ripening process, maintained the quality, and prolonged the shelf life of fruits. As this is an inexpensive technique, it may be used commercially.

Morus nigra L., or mulberry, is a susceptible fleshy fruit due to its high respiratory rate and low storage stability, which shortens its shelf life and makes it difficult to commercialize in natura. Edible coatings, thin membranes produced directly on the desired surface, could improve food preservation, among other properties. Annatto (Bixa orellana L.) seeds are natural pigments with high antioxidant activity. This work aimed to develop a pectin-based edible coating with annatto extract to increase the shelf life of fruits, using mulberries as a study model. The mulberries were randomly separated into five groups: without coating, coated with different extract concentrations (0%, 5%, and 10%), and a layer-by-layer treatment consisting of a pectin layer under a 10% extract layer. The samples were evaluated for the following parameters: titratable acidity, maturity index, mass loss, pH, soluble solids, moisture contents, and bioactive compounds. The coated group with 10% annatto extract had the best result for the maturity index (25.52), while the group with 5% showed better mass loss and moisture (37.28% and 83.66%, respectively). Herein, it was demonstrated that pectin-based edible coatings with annatto extract delay the maturation and senescence of mulberries, preserving the bioactive compounds and increasing shelf life.