Harvest time is one of the main factors related to guava fruit postharvest losses. It is subjectively determined by fruit size and skin color, without any consensual standardization among the growers. The use of maturity indexes enables growers to know the ideal harvest time according to each market situation. The objective of this work was to determine the maturity indexes to identify the harvest time for guava fruit cv. Kumagai and Paluma. Skin color, fruit firmness, soluble solids, titratable acidity, ratio and ascorbic acid were analyzed. The most adequate maturity indexes for 'Kumagai' guava fruit were skin color and pulp firmness, while for 'Paluma' guava fruit, the best indexes were skin color, pulp firmness, titratable acidity and ratio.

Guava (Psidium guajava L.) is a tropical fruit that presents fast post-harvest ripening; therefore it is a very perishable product. Inappropriate storage temperature and retail practices can accelerate fruit quality loss. The objective of this study was to evaluate the respiratory activity (RA), the ethylene production (EP) and Q 10 of guava fruit at different storage temperatures. 'Paluma' guava fruits were harvested at maturity stage 1 (dark-green skin) and stored at either 1, 11, 21, 31 or 41ºC; RA and EP were determined after 12, 36, 84 and 156 h of storage. RA and EP rates at 1 and 11ºC were the lowest -0.16 and 0.43 mmol CO 2 kg -1 h -1 and 0.003 and 0.019 µmol C 2 H 4 kg -1 h -1 , respectively. When guavas were stored at 21ºC, a gradual increase occurred in RA and EP, reaching 2.24 mmol CO 2 kg -1 h -1 and 0.20 µmol C 2 H 4 kg -1 h -1 , after 156 h of storage. The highest RA and EP were recorded for guavas stored at 31ºC. In spite of high RA, guavas stored at 41ºC presented EP similar to guavas stored at 11ºC, an indicator of heat-stress injury. Considering the 1-11ºC range, the mean Q 10 value was around 3.0; the Q 10 value almost duplicated at 11-21ºC range (5.9). At 21-31ºC and 31-41ºC, Q 10 was 1.5 and 0.8, respectively. Knowing Q 10 , respiratory variation and ripening behavior in response to different temperatures, fruit storage and retail conditions can be optimized to reduce quality losses. , respectivamente. Quando as goiabas foram armazenadas a 21ºC, observou-se aumento gradual em AR e PE, as quais alcançaram valores de 2,24 mmol CO 2 kg -1 h -1 e 0,20 µmol C 2 H 4 kg -1 h -1 após 156 h de armazenamento. As maiores AR e PE foram observadas em goiabas armazenadas a 31ºC. Apesar de alta AR, goiabas armazenadas a 41ºC tiveram baixa PE, similarmente àquelas armazenadas a 11ºC, indicando dano por alta temperatura. Na faixa de 1-11ºC, o valor médio de Q 10 foi de 3,0, enquanto esse valor quase duplicou na faixa de 11-21ºC, atingindo 5,9. O Q 10 decresceu nas faixas de 21-31ºC e 31-41ºC, apresentando valores de 1,5 e 0,8, respectivamente. Conhecendo-se a variação do Q 10 , da taxa respiratória e do comportamento do amadurecimento em resposta a diferentes temperaturas, as condições de armazenamento e comercialização dos frutos podem ser otimizadas para reduzir as perdas na qualidade.

RESUMO-Este trabalho teve como objetivo estudar a influência do estádio de maturação na qualidade de goiabas 'Kumagai' e 'Paluma'. Frutos sadios das duas cultivares colhidos em cinco estádios de maturação, definidos com base na coloração da casca e armazenados sob condição de ambiente (25±1ºC e 85±5% UR), foram avaliados na ocasião da colheita e após atingirem completo amadurecimento quanto à vida útil, coloração da casca, firmeza da polpa, teores de ácido ascórbico, sólidos solúveis (SS) e acidez titulável (AT), assim como quanto à relação SS/AT e ao sabor. Os resultados indicaram que goiabas da cv. Kumagai apresentam maior vida útil (6,8 dias, em média) que as 'Paluma' (3,2 dias, em média) e que este período é influenciado pelo estádio de maturação. Independentemente da cultivar, goiabas colhidas nos estádios iniciais de maturação mantiveram-se mais ácidas (0,71%) que as colhidas mais tardiamente (0,57%), com o agravante de que, na cv. Kumagai, a colheita no estádio 1 resultou em retenção da cor verde da casca. A colheita das goiabas nos estádios iniciais de amadurecimento, apesar de prolongar o período de conservação, implica frutos de qualidade inferior. Por outro lado, a colheita em estádios de maturação mais avançados torna indispensável a implementação de técnicas de conservação adequadas às características intrínsecas de cada cultivar, de modo a garantir a qualidade da fruta oferecida ao consumidor. Termos para indexação: Psidium guajava, amadurecimento, conservação, cultivares. HARVEST TIME AND QUALITY OF KUMAGAI AND PALUMA GUAVASABSTRACT -This research aimed to study the influence of maturation on the quality of 'Kumagai' and 'Paluma' guavas. Healthy fruits of both cultivars harvested at five maturity stages defined on the basis of skin color, were selected for the absence of mechanical damage and rot and stored under environmental conditions (25±1ºC and 85±5% RH). They were evaluated at the time of harvest and after reaching full maturity as the shelf-life, skin color, pulp firmness, ascorbic acid, soluble solids (SS) and titratable acidity (TA), as well as the SS/TA ratio and the flavor. The results indicated that cv. Kumagai guavas have longer conservation (6.8 days on average) than 'Paluma' (3.2 days on average) and that this period is influenced by ripening stage. Regardless of cultivar, guavas harvested in early stages of maturation kept more acid (0.71%) than that those harvested later (0.57%), with the aggravating circumstance that in cv. Kumagai, the harvest in stage 1, resulted in retention of the green color of the skin. the harvest of guava in early stages despite prolonging the shelf-life implies inferior fruit quality. On the other hand, the harvest in more advanced stages of maturation makes necessary the implementation of appropriate conservation techniques to the intrinsic characteristics of each variety, in order to ensure the quality of the fruit offered to the consumer.

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