Freshly characterization and storability of mini head lettuces at optimal and abusive temperatures.

Selection of lettuce varieties less sensitive to quality deterioration and more tolerant to abusive temperatures during handling, transportation, and storage is essential to minimize economical and quality losses that affect both producers and consumers. This work was focused on the quality changes of four baby head lettuces (Lactuca sativa L.), two butter (red and green) and two oak-leaf (red and green) types, during storage at 0 ℃ and 10 ℃ for 10 days. Lettuce quality was determined by measuring bioactive content (ascorbic acid, total phenolics), physicochemical (total chlorophyll, browning potential), and microbiological indices. At harvest, red varieties presented lower browning potential and higher bioactive compounds but no differences were observed in microbial populations. During storage, ascorbic acid underwent first order degradation for all varieties, with a degradation rate at 10 ℃ twice faster than at 0 ℃. At 0 ℃, only the red oak-leaf lettuce exhibited chlorophyll degradation, while at 10 ℃ all varieties presented degradation. No changes were observed in total phenolics and browning potential of butter lettuces during storage at both temperatures. Microbial population counts were significant affected by the storage temperature. Red butter baby lettuce presented slightly better bioactive content and microbiological characteristics and then better storability.

Quality characterization of celery (Apium graveolens L.) by plant zones and two harvest dates.

The aim of this study was to characterize the quality of celery petioles (Apium graveolens L. cv Golden Clause) from the external, middle, and internal zones of each plant. Harvest dates were 93 (HD1) and 124 (HD2) days after transplantation. Total weight (TW), total length (TL), total leaves number (LN), and petiole length of leaves (PL) for the 3 zones were measured. Physicochemical (color, b* and h; texture; total soluble solids, TSS; titratable acidity, TA; water content, WC), nutraceutical (ascorbic acid, AA; total quinones, TQ; browning potential, BP), and sensorial analysis (flavor, fibrosity, crunchiness) were done at harvest on petioles of each zone. No differences between harvesting dates were found in TW, TL, LN, and PL. Middle leaves had the highest PL. Harvest dates were not different in b*, h, TA, AA, and WC. Texture, TSS, BP, and TQ resulted higher in petioles of HD2 than in HD1. Similar TSS and TA were found in leaves of different plant zones. The yellow color of both external and internal zones was significantly higher than in the middle zone. The texture and BP was similar between the external and middle zones but the WC was lower in the external zone. Similarly, the AA content as well as the TQ was also lower than in the middle zone. Harvest delay improved the nutraceutical value in terms of BP and TQ, even though it also resulted in pithiness and fibrosity of the leaves. This study therefore suggests that the petioles of the middle zone when harvested at HD1 are the most suitable for consumption. Practical Application: Celery is a vegetable reduced in calories, has a high nutritional value and its fresh petioles are mainly consumed in salads. The texture and flavor are the most important attributes that define consumers' acceptability. As nutritional value, texture, and flavor may change with plant age and different zones of the plant, harvest date plays an important role on quality. Results indicate that harvest delay improved the nutraceutical value even though it also resulted in pithiness and fibrosity of the stalks. Petioles of the middle zone, when harvested at 93 d after transplanting, are the most suitable for consumers' consumption.