Controlling Temperature and Water Loss to Maintain Ascorbic Acid Levels in Strawberries During Postharvest Handling

Abstract

Chandler', 'Oso Grande' and 'Sweet Charlie' strawberries were stored for 8 days at 1 or 10°C, or 4 days at 20°C, either unwrapped or wrapped in PVC film to retard water loss. Total ascorbic acid (AA) content was expressed on a dry weight basis to correct for water loss differences between treatments. Loss of AA was low and did not differ between wrapped treatments at 1 and 10°C, but was much greater at 20°C. Wrapping reduced AA loss by 5-fold at 1 and 10°C and by 2-fold at 20°C. The effect was not due to modification of O 2 and CO 2 levels in wrapped treatments, which was minimal. The results indicate that water loss had a greater effect on AA levels than temperature. Combining wrapping with storage at 1 or 10°C reduced AA loss by 7.5-fold compared to unwrapped strawberries stored at 20°C.

Armazenagem de morangos cv. Camarosa e cv. Verão em atmosfera modificada

“…Autores como Nunes et al (1998) atribuíram a manutenção da vitamina C em morangos às altas umidades relativas dentro das embalagens plásticas. Wright e Kader (1997) obtiveram resultado semelhante com morangos da cv.…”

Postharvest Handling of Berries

“…Similarly, storage of strawberries at 1°C together with moisture loss control reduced losses of total ascorbic acid by 7.5-fold compared to fruit stored at 20°C [40]. These authors concluded that even short periods at ambient temperature without control of water loss could result in considerable losses of total AA in strawberries.…”

Uso de la deshidratación osmótica por etapas para prolongar la vida pos-cosecha de guayaba Use of osmotic dehydration by stages to extend the postharvest life of guava

“…Existen artı´culos que sugieren que los dan˜os meca´nicos, podredumbre y senescencia promueven la pe´rdida de agua y la desorganizacio´n de la pared celular estimulando con ello la oxidacio´n de la vitamina C, probablemente debido a la presencia de enzimas polifenol oxidasa y a´cido asco´rbico oxidasa (Mokady et al, 1987). Por otro lado, la enzima ascorbato oxidasa, encontrada normalmente en las paredes celulares, puede ser liberada despue´s del dan˜o en el tejido o pe´rdida de agua (Klein, 1987;Loewus & Loewus, 1987;Nunes et al, 1998). La mayor retencio´n de vitamina C en las guayabas DOE comparadas con las frutas control podrı´a deberse a que el tratamiento osmo´tico retuvo mayor cantidad de agua durante el tratamiento y el periodo de almacenamiento, con lo que se evitaron dan˜os celulares y el ataque de enzimas oxidativas.…”