Desiccation sensitivity from different coffee seed phenological stages

Abstract

-Maturity stage and drying method are the factors that most influence coffee seed quality. The objective of this study was to assess the physiological quality and investigate the electrophoretic patterns of catalase and endo-ß-mannanase enzymes and heat resistant proteins in coffee seeds harvested at different phenological stages and dried under different conditions. Physiological quality was assessed when the seeds had developed the green, greenish-yellow, cherry, overripe and dry stages after three treatments: no drying, conventional drying and fast drying. After each treatment, the physiological quality of the seeds was assessed using the germination test and electrophoretic patterns of heat resistant proteins and the activity of catalase and endo-ß-mannanase enzymes. Seeds harvested at the cherry phenological stage had the best physiological quality, and the drying process reduced quality at the cherry, overripe and dry stages. This reduction was greater under the faster drying process, but at the greenish-yellow stage, seeds had better physiological quality after slow drying. Regarding the results from electrophoretic analysis, endo-ß-mannanase and catalase activities increase as the ripeness stages advance; the activity of endo-ß-mannanase is directly associated with the deterioration process; the expression of heat resistant proteins increases with maturation process and is associated with seed physiological quality.Index terms: Coffea arabica L., seed drying, physiological quality, protein profile.Sensibilidade à dessecação de sementes de café em diferentes estádios fenológicos RESUMO -O estádio de maturação e a secagem são os fatores que mais influenciam a qualidade de sementes de café. O objetivo foi avaliar a qualidade fisiológica e investigar os padrões eletroforéticos das enzimas catalase, endo-ß-mananase e das proteínas resistentes ao calor em sementes de café, em diferentes estádios e secadas em diferentes condições. Avaliouse a qualidade nos estádios verde, verde cana, cereja, passa e seco, após tratamentos de secagem: sem secagem, secagem convencional e secagem rápida. A qualidade fisiológica foi avaliada pelo teste de germinação, padrão eletroforético das proteínas resistentes ao calor e atividade das enzimas catalase e endo-β-mannanase. Sementes colhidas no estádio cereja apresentam melhor qualidade fisiológica e a secagem reduz a qualidade das sementes colhidas nos estádios de maturação cereja, passa e seco. Esta redução foi maior após secagem mais rápida, mas no estádio verde cana as sementes apresentam melhor desempenho fisiológico após secagem lenta. Com relação às análises eletroforéticas, a atividade das enzimas endo-ß-mannanase e catalase aumenta quando o processo de maturação avança; a atividade da endo-ß-mannanase está diretamente relacionada com o processo de deterioração; a expressão de proteínas resistentes ao calor aumenta com a maturação e está associada à qualidade fisiológica das sementes de café.Termos para indexação: Coffea arabica L., secagem, qualidade fisiológica,...

Behavior of coffee seeds to desiccation tolerance and storage

“…The results confirm that moister seeds substantially lose quality during storage, which can be seen in the results of the germination and vigor tests. Lower activity of catalase was observed in the seeds that were not dried, a finding similar to the one by Santos et al (2014) in coffee seeds, which suggests that the loss of seed viability during the drying process is followed by an increase in the levels of reactive oxygen species (ROS) because of the physiological stress suffered. According to Takahashi et al (2007), seeds have mechanisms to prevent the formation of ROS.…”

“…Coffee seeds are classified as having an intermediate behavior towards drying and storage (Ellis et al, 1991), based on the fact that they tolerate storage for up to twelve months at 15 °C after desiccation to approximately 10% water content. However, existing studies on the performance of coffee seeds after drying and storage are contradictory and inconclusive (Santos et al, 2013). Research conducted with the aim of determining techniques to extend the shelf life of coffee seeds have shown conflicting results, especially for water content (Gentil, 2001).…”

“…Thus, damage to membrane systems may occur during fast drying, preventing recovery processes. Thus, more time may be required for repairs during germination (Santos et al, 2013).…”

Cryopreservation of coffee seeds: a simplified method

“…Lower activity of CAT in coffee seeds that did not undergo physiological stress was also found by Santos et al (2014) and Abreu et al (2014), confirming that loss of seed viability during the drying and cryopreservation is followed by an increase in the levels of reactive oxygen species (ROS) due to the physiological stress that occurred.…”

Efecto del secado y presecado mecánico previo al almacenamiento en la calidad del grano de café (Coffea arabica L.)

“…El secado mecánico del café puede reducir la calidad fisiológica de los granos, indicado por la actividad de enzimas asociadas al deterioro (Santos et al 2014). El secado al sol ha sido identificado por algunos, como parte fundamental, para la obtención de cafés de muy buena calidad física y en taza.…”