A Review Study on the Postharvest Decay Control of Fruit by <em>Trichoderma</em>

This chapter consists of an overview with the most relevant results about the efficacy of Trichoderma on postharvest disease control. The results of investigations demonstrate that this fungus can control several phytopathogens in different fruits. Postharvest losses represent a major problem in several countries. The constant application of fungicides not only at field but also at postharvest stage has led to microbial resistance cases, which make the control of these pathogens difficult. Biological control is a promising alternative to chemical fungicide applications. In this sense, an eco-friendly alternative and effective approach for controlling diseases is the use of microbial antagonists like Trichoderma, which have several mechanisms of action to stop disease development. A crucial treat in biological control is related to the maintenance of microbial viability and efficacy, that is why other technologies like their incorporation into edible films and coatings, nanotechnology, microbial mixtures, among others have been applied in combination with Trichoderma successfully. An enhancement in biocontrol activity is achieved when alternative systems are combined like GRAS substances, biopolymers, and other antagonists. Thus, Trichoderma is an eco-friendly alternative to threat postharvest diseases as an alternative to chemical treatments

Alternative Eco-Friendly Methods in the Control of Post-Harvest Decay of Tropical and Subtropical Fruits

The effectiveness on several fruits by the application of alternative methods against fungi is summarized in the present chapter. Several investigations have reported the efficacy of these technologies for controlling fungal infections. Currently, high post-harvest loses have been reported due to several factors such as inefficient management, lack of training for farmers, and problems with appropriate conditions for storage of fruits and vegetables. Even now, in many countries, post-harvest disease control is led by the application of chemical fungicides. However, in this time, awareness about fungi resistance, environmental, and health issues has led to the research of eco-friendly and effective alternatives for disease management. The pathogen establishment on fruits can be affected by the application of GRAS compounds like chitosan, essential oils, salts, among others; besides, their efficacy can be enhanced by their combination with other technologies like ultrasound. Thus, the applications of these alternatives are suitable approaches for post-harvest management of fruits

Evaluación in vitro del quitosano y aceites esenciales para el control de dos especies patógenas de Colletotrichum aisladas de aguacate (Persea americana Mill)

The antifungal activity of chitosan, essential oils (cinnamon and eucalyptus) and their combination were evaluated against two pathogens Colletotrichum acutatum and Colletotrichum gloeosporioides isolated from avocado (Persea americana Mill). Chitosan was used at different concentrations (0.1, 0.5 and 1.0%). The concentrations of essential oils evaluated were 0.1, 0.5 and 2.0% (eucalyptus and cinnamon). The effect of the combination of chitosan with the essential oils was evaluated using the most effective concentrations of chitosan (0.1 and 0.5%) and the essential oil with the highest inhibitory effect (2%).The treatments of chitosan and essential oils were partially effective against fungal development by inhibiting mycelial growth in a range of 17 to 21% and 18 to 50%, respectively. The mycelia growth of both strains was totally reduced by the application of chitosan (0.1%) with cinnamon essential oil (2%), however; the combination of chitosan with eucalyptus essential oil was not effective. To our knowledge this research is the first that reports chitosan resistant strains of Colletotrichum isolated from avocado fruits.La actividad antifúngica del quitosano, aceites esenciales (canela y eucalipto) y su combinación fueron evaluadas contra dos patógenos Colletotrichum acutatum y Colletotrichum gloeosporioides aislados de aguacate (Persea americana Mill). Se utilizó quitosano a diferentes concentraciones (0.1, 0.5 y 1.0%). Las concentraciones de aceites esenciales evaluadas fueron 0.1, 0.5 y 2.0% (eucalipto y canela). El efecto de la combinación del quitosano con los aceites esenciales se evaluó utilizando las concentraciones más eficaces del quitosano (0.1 y 0.5%) y el aceite esencial de eucalipto y canela con el mayor efecto inhibitorio (2%). Los tratamientos de quitosano y aceites esenciales cada uno por separado fueron parcialmente efectivos para evitar el desarrollo de las cepas evaluadas, inhibiendo el crecimiento micelial en un rango de 17 a 21% y 18 a 50% respectivamente. Por lo contrario, el crecimiento micelial de ambas cepas fue totalmente reducido mediante la aplicación combinada del quitosano (0.1%) con aceite esencial de canela (2%), sin embargo; la combinación del quitosano con aceite esencial de eucalipto no fue efectiva. Hasta donde sabemos, esta investigación es la primera que informa sobre cepas de Colletotrichum resistentes al quitosano aisladas de frutos de aguacate

Ionic Liquids and Organic Solvents for Recovering Lignin from Lignocellulosic Biomass

Lignin contributes to the recalcitrance of lignocellulosic biomass and affects enzymatic activity during biorefinery operations. Therefore, it must be removed before further processing. Organic solvents (organosolv) and ionic liquids are two important pretreatments for delignifying lignocellulosic biomass. They have proven beneficial for fractionating and recovering cellulose and hemicellulose, as well as lignin with useful physicochemical properties. Volatility and harsh conditions of the acidic systems that result in toxicity, corrosion, and pollution are the main problems of organosolv. Ionic liquids, generally recognized as green solvents, have also been proposed as a possible solution to the challenge of using lignocellulosic biomass. Ionic liquids can either dissolve the lignocellulosic biomass completely or dissolve it into individual fractions. This review considers the advantages and disadvantages of organosolv and ionic liquids, since both are important methods to fractionate lignocellulosic biomass in their main components which can be converted into value added products

Estabilidad oxidativa y contenido de compuestos fenólicos durante el almacenamiento del salvado de sorgo (Sorghum bicolor (L.) Moench) extrudido

Sorghum bran has a high antioxidant capacity due to the high concentrations of phenolic compounds. During decortication of the sorghum grain to obtain the bran, lipid oxidation reactions may occur that cause deterioration in its quality. To avoid this, thermal stabilization processes such as extrusion are used. The objective of this work was to evaluate chemical, stability of phenolic compounds and antioxidant capacity changes of extruded red sorghum bran. Raw sorghum bran (SC) and extruded (SE) sorghum bran were stored for 42 days and chemical (peroxide index, pH, free fatty acid), phenolic compounds, antioxidant capacity and phenolic acids determinations were carried out. The type of bran was the factor that most affected results of the chemical evaluations. The SE showed greater stability in quality than the SC, which had significant changes in free fatty acid and peroxide index. The content of phenolic compounds and the antioxidant capacity of both types of bran were not modified by the effect of storage. However, the SE presented higher levels of both parameters than the SC. The sorghum bran extrusion process retards enzymatic oxidation of lipids and improves the extraction of phenolic compounds.El salvado de sorgo posee una alta capacidad antioxidante debido a su elevado contenido de compuestos fenólicos. Durante el decorticado del grano para la obtención del salvado, pueden presentarse reacciones de oxidación lipídica que deterioran su calidad. Para evitar esto, se emplean procesos de estabilización como la extrusión. El objetivo de este trabajo fue evaluar los cambios químicos en los compuestos fenólicos y la capacidad antioxidante del salvado de sorgo rojo extrudido. Los salvados de sorgo crudo (SC) y extrudido (SE) se almacenaron durante 42 días para poder evaluar los cambios químicos (índice de peróxidos, pH y ácidos grasos libres), en los compuestos fenólicos, su capacidad antioxidante y la presencia de ácidos fenólicos. El tipo de salvado fue el factor que más afectó los resultados de las evaluaciones químicas. La calidad del SE fue más estable en comparación con la del SC, el cual tuvo cambios significativos de ácidos grasos libres e índice de peróxidos. El contenido de compuestos fenólicos y la capacidad antioxidante de ambos tipos de salvado no se modificaron significativamente (p > 0.05) por efecto del tiempo de almacenamiento, sin embargo, el SE presentó niveles superiores en compuestos fenólicos y capacidad antioxidante que el SC. El proceso de extrusión del salvado de sorgo retarda la oxidación enzimática y mejora la extracción de los compuestos fenólicos

Biosynthesis of Silver Nanoparticles Using Seasonal Samples of Sonoran Desert Propolis: Evaluation of Its Antibacterial Activity against Clinical Isolates of Multi-Drug Resistant Bacteria

Multi-drug resistant (MDR) bacteria have gained importance as a health problem worldwide, and novel antibacterial agents are needed to combat them. Silver nanoparticles (AgNPs) have been studied as a potent antimicrobial agent, capable of countering MDR bacteria; nevertheless, their conventional synthesis methods can produce cytotoxicity and environmental hazards. Biosynthesis of silver nanoparticles has emerged as an alternative to reduce the cytotoxic and environmental problems derived from their chemical synthesis, using natural products as a reducing and stabilizing agent. Sonoran Desert propolis (SP) is a poplar-type propolis rich in polyphenolic compounds with remarkable biological activities, such as being antioxidant, antiproliferative, and antimicrobial, and is a suitable candidate for synthesis of AgNPs. In this study, we synthesized AgNPs using SP methanolic extract (SP-AgNPs) and evaluated the reduction capacity of their seasonal samples and main chemical constituents. Their cytotoxicity against mammalian cell lines and antibacterial activity against multi-drug resistant bacteria were assessed. Quercetin and galangin showed the best-reduction capacity for synthesizing AgNPs, as well as the seasonal sample from winter (SPw-AgNPs). The SPw-AgNPs had a mean size of around 16.5 ± 5.3 nm, were stable in different culture media, and the presence of propolis constituents was confirmed by FT-IR and HPLC assays. The SPw-AgNPs were non-cytotoxic to ARPE-19 and HeLa cell lines and presented remarkable antibacterial and antibiofilm activity against multi-drug resistant clinical isolates, with E. coli 34 and ATCC 25922 being the most susceptible (MBC = 25 μg/mL), followed by E. coli 2, 29, 37 and PNG (MBC = 50 μg/mL), and finally E. coli 37 and S. aureus ATCC 25923 (MBC = 100 μg/mL). These results demonstrated the efficacy of SP as a reducing and stabilizing agent for synthesis of AgNPs and their capacity as an antibacterial agent