Miluska M. Zamalloa-Puma

Pollution indexes are instruments that allow a quick interpretation of water quality, combining physical, chemical, and microbiological parameters to generate a numerical value. Our aim was to evaluate spatial and temporal-spatial water quality and propose a water pollution index (WPI) for high Andean rivers using multivariate statistics. Data on physical, chemical, and microbiological parameters were collected from the river water of the Chumbao sub-basin during the rainy and dry seasons at eight sampling points. The laboratory and field analysis methods were developed following the methodology proposed by the APHA. Spearman’s correlation, cluster analysis, and discriminate analysis were applied to evaluate water quality’s spatial and temporal variation and principal component analysis/factor analysis to identify critical parameters to formulate the Water Pollution Index (WPI). The parameters with the most incidence in water quality were color, conductivity, dissolved oxygen, biochemical demand oxygen, ammonia, total phosphorus, lead, chromium, and thermotolerant coliforms. The inorganic pollution index (IPI) was obtained from conductivity, lead, and chromium, reporting pollution levels for the river water between “none” to “high”; and the organic pollution index (OPI) was obtained from dissolved oxygen, biochemical demand oxygen, ammonia, total phosphorus, color, and thermotolerant coliforms, with levels of “low” to “very high” pollution. The proposed pollution indexes are water management instruments that evaluate water quality.

Prickly pear fruits are seasonal and have shades ranging from pale green to deep purple. Their pigments are associated with bioactive compounds, being sensitive to thermal transformation processes for their conservation. The objective of this research was to evaluate the bioactive compounds and the sensory analysis of freeze-dried prickly pear fruits from an inter-Andean valley in Peru. The prickly pear fruits of the morada, anaranjada, and blanca ecotypes came from an inter-Andean valley in Peru at 2972 m altitude. The sliced fruits were freeze-dried at −40 °C and 0.25 mTorr, and the total polyphenol content (TPC), vitamin C, and antioxidant activity (AA) were determined, as well as the color L* a* b*, color index (CI*), FTIR spectra, and mineral content. In the same way, sensory analysis of preferences with nine scales was applied. It was observed that in the freeze-dried fruits, TPC, AA, and vitamin C increased significantly (p-value < 0.05), and their corresponding functional groups increased in intensity in their corresponding FTIR spectra; furthermore, trace elements such as Cu, Fe, Se, Zn, Si, and Mn were identified. On the other hand, freeze-drying provided deeper colors to the fruits, which most panelists said they “very much liked” during the sensory analysis, although the texture was not very well accepted, with most panelists reporting being “indifferent” towards it. The freeze-drying technique allows the bioactive and sensory attributes of prickly pear fruits from inter-Andean valleys to be preserved, making it a potential fruit for export and conservation due to its seasonality.

Ethanolic extracts of propolis and bee honey contain substances beneficial to human health. Mixtures of wall materials were compared in spray-drying microencapsulation of ethanolic extracts of propolis and bee honey rich in bioactive compounds. Maltodextrin and tara gum were used to obtain microencapsulates A, and modified native potato starch and tara gum were used for microencapsulates B. High values of phenolic compounds, flavonoids, and antioxidant capacity were obtained in microcapsules A and B, and the results obtained in terms of encapsulation efficiency, yield, hygroscopicity, solubility, moisture, Aw, bulk density, and color were typical of the spray-drying process. On the other hand, spherical and elliptical microparticles of sizes between 7.83 and 53.7 µm with light and medium stability were observed. Thermogravimetric properties were similar in both microencapsulates; total organic carbon, SEM-EDS, and FTIR analyses corroborated the encapsulation. X-ray diffractogram exhibited amorphous structures, and the release kinetics of phenolic compounds presented high values from 8.13 to 12.58 mg GAE/g between 7 and 13 h. Finally, modified potato starch is a better encapsulant than maltodextrin because it has better core protection and controlled release of the encapsulated bioactive compounds.

The cellulose from agroindustrial waste can be treated and converted into nanocrystals or nanofibers. It could be used to produce biodegradable and edible films, contributing to the circular economy and being environmentally friendly. This research aimed to develop an edible film elaborated with activated cellulose nanocrystals, native potato starch, and glycerin. The activated cellulose nanocrystals were obtained by basic/acid digestion and esterification with citric acid from corn husks. The starch was extracted from the native potato cultivated at 3500 m of altitude. Four film formulations were elaborated with potato starch (2.6 to 4.4%), cellulose nanocrystals (0.0 to 0.12%), and glycerin (3.0 to 4.2%), by thermoforming at 60 °C. It was observed that the cellulose nanocrystals reported an average size of 676.0 nm. The films mainly present hydroxyl, carbonyl, and carboxyl groups that stabilize the polymeric matrix. It was observed that the addition of cellulose nanocrystals in the films significantly increased (p-value < 0.05) water activity (0.409 to 0.447), whiteness index (96.92 to 97.27), and organic carbon content. In opposition to gelatinization temperature (156.7 to 150.1 °C), transparency (6.69 to 6.17), resistance to traction (22.29 to 14.33 N/mm), and solubility in acidic, basic, ethanol, and water media decreased. However, no significant differences were observed in the thermal decomposition of the films evaluated through TGA analysis. The addition of cellulose nanocrystals in the films gives it good mechanical and thermal resistance qualities, with low solubility, making it a potential food-coating material.

Adsorption isotherms provide insight into the thermodynamic properties governed by food storage conditions. Adsorption isotherms of purple corn of the Canteño variety were evaluated at 18, 25, and 30 °C, for the equilibrium relative humidity (ERH) range between 0.065 and 0.95. The equilibrium moisture (X_e) was determined by the continuous weight-change method. Seven mathematical models of isotherms were modeled, using the coefficient of determination R², mean absolute error (MAE), and estimated standard error (ESE) as the convergence criterion. Thermodynamic parameters such as isosteric heat (q_st), Gibbs Free Energy (ΔG), differential entropy (ΔS), activation energy (E_a), and compliance with the isokinetic law were evaluated. It was observed that the adsorption isotherms presented cross-linking around 75% ERH and 17% X_e, suggesting adequate storage conditions at these values. The GAB and Halsey models reported better fit (R² > 97%, MAE < 10%, ESE < 0.014 and random residual dispersion). The reduction of X_e from 17 to 7%, increases q_st, from 7.7022 to 0.0165 kJ/g, while ΔG decreases considerably with the increase in X_e, presenting non-spontaneous endergonic behavior, and linear relationship with ΔS, evidencing compliance with the isokinetic theory, governed by q_st. E_a showed that more energy is required to remove water molecules from the upper layers bound to the monolayer, evaluated using C_GAB. The models predicted the storage conditions, and the thermodynamic parameters show the structural stability of the purple corn grains of the Canteño variety during storage.

The water from the high Andean rivers is peculiar due to its composition and the geomorphology of its sources, and naturally or anthropogenically contamination is not discarded along its course. This water is used for agriculture and human consumption, therefore knowing its quality is important. This research aimed to proposing and formulate a water-quality index for high Andean basins through the Delphi method, and its application in the Chumbao River located in Andahuaylas-Peru. Forty-three water-quality parameters were evaluated through the Delphi method, and the water-quality index (WQI_HA) was formulated with a weighted average of the weights of the selected parameters, it was compared with the WQI Dinius. For this purpose, ten sampling points were considered along the Chumbao River located between 4274 and 2572 m of altitude and the WQI_HA was applied. In addition, field and laboratory analyses were carried out in 2018, 2019, and 2021, in dry and rainy seasons. Twenty parameters were grouped in the physicochemical sub-index (SI_PC), heavy metals sub-index (SI_HM), and organic matter sub-index (SI_OM). Each group contributed with weights of 0.30, 0.30, and 0.40, respectively, for the WQI_HA formulation. The SI_PC and SI_OM showed that the areas near the head of the basin presented excellent and good quality, while the urbanized areas were qualified as marginal to poor; SI_HM reported good quality in all points and seasons. Regarding the WQI_HA, the index shows good quality in the zones above 3184 m of altitude, contrasting with poor quality downstream, decreasing notably in both seasons, suggesting continuous degradation of the water body.