Graphical abstract

The objective of this work was the recovery of chitosan by ultrasound-assisted extraction (UAE) from white shrimp (Litopenaeus vannamei) chitin, and the physicochemical and structural characterization of the obtained biopolymer, as well as its antimicrobial effect on Pythium ultimum growth. A 23 factorial design was used to evaluate chitosan extraction conditions. Instrumental analysis techniques for chitosan characterization and radial growth inhibition, as an antifungal activity test, were performed. The ultrasonically extracted chitosan (UC) reached a yield of 86.96% with 100% solubility, a degree of deacetylation (DDA) >78%, molecular weight (MW) of 3.928 × 105 g mol−1, and a crystallinity index (Icr) of 87%, calculated through nuclear magnetic resonance (1H NMR) and Fourier transform infrared spectroscopy (FTIR), size exclusion chromatography (SEC), and X-ray diffraction (XRD), respectively. The inhibitory activity of the chitosan was evaluated against the oomycete Pythium ultimum, observing a 93% radial inhibition over 24 h. UAE proved to be an excellent alternative to the conventional deacetylation, reducing reaction time and obtaining a UC with higher MW and (Icr) than the commercial one, which could potentiate its applications.

No abstract

Peach is a fruit highly appreciated by consumers; however, it is highly perishable, so drying is an alternative to preserve its physical and chemical properties. In this study, the effect of drying in natural and forced convection at three different temperatures (40 °C, 45 °C and 50 °C) and solar drying with two air velocities (1 m/s and 3 m/s) on the color, texture, total phenol content and antioxidant capacity of peach (Prunus persica (L.) Batsch), were evaluated. The experimental data of the drying kinetics were adjusted to five different mathematical models (Page, Logarithmic, Two-term exponential, Wang and Singh, and Verma et al.). The model that best represented the experimental data in natural convection was the Wang and Singh model (r2 > 0.998; RMSE < 0.016; χ2 < 2.85 × 10−4); in forced convection (45 °C and 50 °C), it was the Verma et al. model (r2 > 0.997; RMSE < 0.025; χ2 < 8.12 × 10−4); and finally, for solar drying, it was the Logarithmic model at 3 m/s (r2 = 0.999; RMSE < 0.012; χ2 < 1.12 × 10−4) and Wang and Sing model (1 m/s) (r2 = 0.998; RMSE = 1.31 × 10−4; χ2 = 1.92 × 10−4). The highest color difference was in samples dried by the natural convection method. The highest values of hardness were obtained by the solar drying method. The value of chlorogenic acid increased with the temperature of natural convection, while the concentration of neochlorogenic acid increased with the temperature at forced convection. For solar drying, the values of chlorogenic acid were greater at 3 m/s; in contrast, the neochlorogenic acid was greater at 1 m/s.

In the present work, the total phenolic content (TPC), total flavonoids content (TFC), antioxidant activity, and phenolic profile from pulp (PU) and peel (PE) extracts obtained from the ciricote (Cordia dodecandra A. DC.) fruit by ultrasound-assisted extraction (UAE) in immature (IM), semimature (SM), and mature (MM) stages were investigated. The effect of the diameter of the ultrasonic probe in the IM stage was also evaluated. The TPC and antioxidant activity in IM fruit extracts by UAE increased up to 11.01 and 23.82 times, respectively, compared to the maceration method. The main phenolic compounds in the PE of IM fruit identified by UPLC-DAD-ESI-MS/MS were quantified as caffeic acid, rutin, and rosmarinic acid, distributed as 45.82, 41.45, and 12.72%, respectively. The PE extracts of IM fruit obtained with the 3 mm diameter probe had 1.27, 2.44, and 1.37 times the TPC (19.93 ± 0.28 mg GAE (Gallic equivalents) g−1 dw), TFC (34.85 ± 4.99 mg RE (Rutin equivalents) g−1 dw), and antioxidant activity (122.09 ± 17.09 µTE (Trolox equivalents) g−1 (DPPH)), respectively, compared to those obtained with a 13 mm diameter probe. The results obtained suggest the use of the ciricote native fruit as a source of bioactive compounds, directly as fresh fruit or processed, thus helping to increase its production and consumption.

Abstract. Phenolic compounds and capsaicinoids present in different tissues (placenta, pericarp, and seeds) of the chili pepper fruit Capsicum annuum L. (cv. xcatik) cultivated in the Yucatán peninsula (Mexico) were analyzed. For this purpose, fresh and dehydrated chili peppers tissues were used. The phenolic compounds and capsaicinoids were extracted using ultrasound-assisted extraction (UAE) and compared to the maceration method. Extracts from each fruit tissue were studied for their antioxidant properties, and a phenolic profile of the whole fruit was performed using ultra-high-performance liquid chromatography with a photodiode array detector coupled to mass spectrometry (UPLC-PAD-ESI-MS). The xcatik chili pepper (XCP) presented a high content of phenolic compounds (11.67±3.34 mg GAE/g DW). The capsaicin:dihydrocapsaicin ratio was 2:1. Additionally, 17 phenolic compounds were detected in the extract of the whole fruit. This study provides a first scan of the phenolic composition and capsaicinoids content of the different tissues of the XCP fruit, as well as the correlation of these bioactive compounds with the antioxidant capacity, highlighting the recovery of bioactive compounds with great antioxidant power.   Resumen. El contenido de compuestos fenólicos y capsaicinoides presentes en diferentes tejidos (placenta, pericarpio y semilla) de los frutos de chile Capsicum annuum L. (cv. xcatik) cultivados en la península de Yucatán (Mexico) fue analizado. Para dicho propósito, los tejidos frescos y deshidratados fueron evaluados. Los compuestos fenólicos y los capsaicinoides fueron extraídos usando la Extracción Asistida por Ultrasonido (EAU) y comparados con el método de maceración. Los extractos de cada tejido del fruto fueron estudiados con relación a sus propiedades antioxidantes, y el perfil fenólico del fruto completo fue realizado usando cromatografía líquida de ultra alta resolución con un detector de arreglo de fotodiodos y acoplado a espectrometría de masas (UPLC-PAD-ESI-MS). El chile xcatik (XCP) demostró ser un fruto con alto contenido de compuestos fenólicos (11.67±3.34 mg GAE/g peso seco). La relación capsaicina:dihidrocapsaicina fue 2:1. Adicionalmente, la presencia de 17 compuestos fenólicos fue detectada en el extracto del fruto completo. Este estudio proporciona un primer barrido de la composición fenólica y el contenido de capsaicinoides de los diferentes tejidos del fruto XCP, así como la correlación de estos compuestos bioactivos con la actividad antioxidante, resaltando la recuperación de compuestos bioactivos con un alto poder antioxidante.