This study investigated the effect of the simulated refrigerated distribution environment on the quality characteristics of green lettuce and ground meat. The simulated refrigerated distribution conditions were as follows: (A) the door was not opened while storing the product in the refrigerator, (B) the door was opened for 20 s every 10 min, and (C) the door was opened for 1 min every 10 min (C). In A, B, and C conditions, the bottom temperature was higher, and the average temperature and temperature deviation of the inside of the packaging box, green lettuce, and ground meat increased according to door opening time. According to simulated refrigerated distribution conditions, food qualities such as browning index, total chlorophyll content, and vitamin C content in green lettuce, moisture content, water holding capacity, and volatile basic nitrogen in ground meat were changed.
This study was conducted to investigate the effects of summer green manure crops as an alternative for imported expeller cake fertilizer on environment-friendly lettuce production. Sunnhemp, soybean, sudangrass, and sorghum, as summer green manure crops, were evaluated under the condition of a plastic film house. In the amount of nitrogen supplied through cultivation of green manure crops, soybean plot, which supplied 187 kg ha-1, was the highest, followed by sorghum plot, 156 kg ha-1. Since all green manure plots supplied more nitrogen than that required by soil testing, it was possible to replace the nitrogen supply of expeller cake fertilizer with the amount of nitrogen produced by green manures for autumn lettuce cultivation. N nutrient balances in sunnhemp, sudangrass, soybean, and sorghum plots were 13 kg ha-1, 28 kg ha-1, 30 kg ha-1, and 38 kg ha-1, respectively. The initial yield and total yield of lettuce showed no significant difference in green manure plots compared to the expeller cake plot, but . It was thought that all green manure crops could be substituted for expeller cake fertilizer used as nitrogen fertilizer, but it would be necessary to adjust the cultivation period and reduction point according to the type of green manure in order to maintain the C/N ratio, nitrogen supply, and nitrogen balance suitable for lettuce production.
Recently, as a natural substance has been emphasized interest in research to enhance the immune function. Green lettuce (Lactuca sativa L.) is a popular vegetable used fresh and it contains various phytochemicals and antioxidant compounds, and has been reported to have various physiological activities such as antibacterial, antioxidant, antitumor and anti-mutagenic. However, only a few studies have investigated on the mechanism of action of immune-enhancing activity of lettuce. Therefore, in this study, the immunomodulatory activities and potential mechanism of action of Green lettuce extracts (GLE) were evaluated in the murine macrophage cell line RAW264.7. GLE significantly increased NO levels by RAW264.7 cells, as well as expressions of immunomodulators such as iNOS, COX-2, IL-1β, IL-6, IL-12, TNF-α and MCP-1. Although GLE activated ERK1/2, p38, JNK and NF-κB, GLE-mediated expressions of immunomodulators was dependent on p38, JNK and NF-κB. In addition, TLR4 inhibition blocked GLE-mediated expressions of immunomodulators and activation of p38, JNK and NF-κB. Taken together, these results demonstrated that TLR4-MAPK/NF-κB signalling pathways participated in GLE-induced macrophage activation and GLE could be developed as a potential immunomodulating functional food.