บทคัดย่องานวิจัย

หมวดหมู่ : ฐานข้อมูลงานวิจัย

Browning susceptibility of minimally processed Baby and Romaine lettuces.

Castaner, M.; Gil, M. I.; Ruiz, M. V.; Artes, F.;

European Food Research and Technology Year: 1999 Vol: 209 Issue: 1 Pages: 52-56 Ref: 30 ref.

1999

บทคัดย่อ

Browning susceptibility of minimally processed Baby and Romaine lettuces.

This study was conducted to determine the effects of cultivar, tissue susceptibility and storage temperature on the keeping quality of minimally processed Baby and Romaine lettuces. Lettuces grown in Spain were harvested at commercial maturity. Midrib and photosynthetic tissues were lightly processed and stored for up to 7 days at 5 deg C and 13 deg C. Changes in L* and a* values and absorbance at 430 nm were compared. The relationship between polyphenols, phenylalanine ammonia lyase (PAL) and polyphenol oxidase [catechol oxidase] (PPO) activities and browning was examined. Measurements of L* and a* values on midribs showed that browning discoloration was the same for Baby as it was for Romaine lettuces and there was no relationship with temperature. In addition, L* and a* values in photosynthetic tissue indicated a decrease in green pigmentation during storage, especially at 13 deg C. For both kinds of tissue at the end of cold storage, an increase in soluble brown polymers was detected. In mid

ribs, total phenolics increased significantly throughout the storage period because of the tissue-wounding response. The photosynthetic tissue had a higher phenolic content than the midrib tissue. For both kinds of tissue, an increase in PPO activity occurred throughout cold storage. However, PAL activity in midrib tissue only increased initially, followed by a slow decline to reach normal levels. Browning potential estimated by L* values correlated significantly with PPO activity and with absorbance at 430 nm for Romaine lettuce. Based on colour and browning potential, no differences between Romaine and Baby lettuce cultivars were observed. However, photosynthetic tissue was the most suitable tissue for the preparation of minimally processed salad mixes because of its high phenolic content.