A High Performance Liquid Chromatography (HPLC) method was developed and validated to quantify sucrose (non-reducing sugar), glucose, and fructose (reducing sugars) in raw tubers of Solanum tuberosum Group Phureja. Chromatographic analysis was performed using an AMINEX HPX 87H column, at 18 °C, linked to a refraction index detector, at 35 °C. The eluent was 10mM sulfuric acid. The conditions established for the method provided an optimum separation of sugars, citric acid, and malic acid, with resolution values higher or equal to one. Among the four sugar extraction methods tested, the double 50% (v/v) aqueous methanol extraction gave the highest level of analytes. Recovery of this extraction method ranged between 94.14 and 99.77%. The HPLC method was validated for repeatability, reproducibility, linearity, and limits of detection, and quantification. Relative standard deviation was found to be lower than five, when testing repeatability and reproducibility, which is suitable considering a range of acceptability from 5.3 to 7.3. Additionally, the regression analyses supported the method linearity in a range of quantification from 3 to 100 mg/L with regression coefficients values greater than 0.998 for the three analytes. Limits of detection were 3.0 mg/L for the three sugars and limits of quantification were 2.0 mg/L for sucrose and 3.0 mg/L for glucose and fructose. Four Colombian commercial cultivars (Criolla Guaneña, Criolla Paisa, Criolla Galeras, and Criolla Colombia) and five landrace accessions from the Colombian Core Collection of Group Phureja were grown in the district of Usme (Bogotá) fields to analyze their sugar contents. Sucrose, glucose, and fructose contents were found ranging from 0.93 to 3.11 g/100 g tuber dried weight (DW), from 0.25 to 4.53 g/100 g tuber DW, and from 0.10 to 1.49 g/100 g tuber DW, respectively. Therefore, a high range in the variability of sugar contents was found among genotypes. However, the variability was low among technical replicates of the same genotype, revealing an accurate quantification of sugars in Group Phureja. This method can be used to assess the amount of reducing and non-reducing sugars accumulation in potato germplasm.

Because the use of drying at high temperatures might negatively affect the functional properties of fruits, the effect of air-drying at 60°C on the total phenolic content (TPC) and antioxidant capacity (AOC) of cape gooseberry fruit was evaluated at three ripeness stages. The AOC was evaluated with 2,2'-azino-bis(3- ethylbenzothiazoline-6-sulfonic acid) (ABTS ), ferric reducing ability of plasma (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and b-carotene-linoleate assays. The TPC and AOC increased in the fresh fruit as the ripeness stage increased. The TPC increased from 401.8±19.8 to 569.3±22.3 mg GA E/100 g dry weight (DW). The AOC values obtained with ABTS in the fresh fruit (ranging from 79.4±4.5 to 132.7±12.9 mmol trolox/g fruit DW) were comparable to those obtained with FRAP (ranging from 82.9±16.3 to 153.9±31.7 mmol trolox/g fruit DW). The values assessed with DPPH ranged from 21.0±3.2 to 34.1±5.1 mmol trolox/g fruit DW. The b-carotene-linoleate assay gave values ranging from 5.8±1.1 to 12.7±2.0 mmol a-tocoferol/g fruit DW. Air-drying the cape gooseberry fruit had a small influence on the TPC. The air-dried fruit had AOC values ranging from 27 to 164% of the value of the fresh fruit. While the ABTS assay produced higher values in the air-dried fruit than in the fresh fruit, the FRAP, DPPH, and b-carotene-linoleate assays resulted in lower values in the air-dried fruit.

The effects of a 80°C, 1 minute thermal treatment (H treatment) and of the same treatment combined with sucrose (SH treatment) on the chemical and sensory qualities of arazá purée were evaluated during 4 months of storage at -20°C. For the control, an untreated sample (C) was included. The chemical qualities evaluated were vitamin C content, total phenolic compounds (TPC), and antioxidant activity (AoA), which were measured with the ferric reducing ability of plasma (FRAP), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and 1,1-diphenyl-2-picrylhydrazyl (DPPH), while a trained panel was used for the sensory quality evaluation. After 4 months of frozen storage, SH was more effective than H at controlling the loss of chemical quality. SH provided a similar FRAP-AoA (89%) and vitamin C content (87%), as well as a higher TPC (145%), ABTS-AoA (272%), and DPPH-AoA (115%), when compared to C before frozen storage. The total sensory qualities in both the SH purée (15±1) and the H purée (16±1) after 4 months at -20°C were comparable to those of the C purée before the frozen storage (18±2). Therefore, using sucrose combined with a thermal treatment and subsequent frozen storage preserves the chemical and sensory qualities of arazá purée.

La enzima clorofilasa, presente en la corteza del banano bocadillo (Musa accuminata), fue extraída, parcialmente purificada y caracterizada empleando como sustrato clorofila (Chl-a) proveniente también de la corteza de la fruta. Además, se evaluó la intensidad respiratoria, la producción de etileno y la actividad de clorofilasa durante el almacenamiento del banano bocadillo a 20 °C. La caracterización parcial de la clorofilasa indicó que esta enzima tiene un pH óptimo de 7,0, temperatura óptima de 40 °C y, KM y VMAX de 0,034 μM Chl-a y 364 μM Chl-a hidrolizada/min/mg proteína, respectivamente. El ensayo de almacenamiento de los frutos indicó que el climaterio se da luego de 11 días de la cosecha, en el cual la intensidad respiratoria, la producción de etileno y la actividad de clorofilasa fueron máximas. El color verde de la corteza desapareció paulatinamente hasta llegar al climaterio, momento en el que predominó el amarillo. Este estudio permite proponer una relación directa entre la actividad de clorofilasa y la degradación de clorofila.