莴苣是美国的一种主要蔬菜作物，在色调和价值上仅次于土豆。1972年，25万英亩土地的产量超过4800万cwt，农场价值超过2.5亿美元，市场价值超过13亿美元。生菜全年都有供应，其年人均消费量约为22磅，略有增加。在美国商业化种植的四种类型中，即Crisphed（冰山）、butterhead、cos（罗曼）和looseleaf，Crisphed类型是最重要的。这是市场上常见的“头生菜”或“冰山生菜”。莴苣的价值在农田和消费者之间增加了约10倍，或约为4%- 在装运点和零售店之间折叠。因此，在目的地的损失尤其昂贵，不仅意味着食物的损失，而且也意味着所有投入物的浪费。收获、包装、运输和分配所需的劳动力、能源和材料。1967年至1969年间在纽约地区进行的一项研究表明，莴苣在批发、零售和消费者层面的平均损失分别为4.1%、4.6%和7.1%（1）。总损失大概相当于后两个数字（即11.7%）的总和，只反映数量损失。本文回顾了处理生菜的一般程序和实践，并根据商品需求和响应对其进行了评估； 重点是脆头型。有关莴苣的一些物理和生物学特性的总结，请参见附录。引文:研讨会，ASHRAE交易，第80卷，第一部分，加利福尼亚州洛杉矶

Lettuce, a major vegetable crop in the U.S., is second in tonage and value to potatoes. In 1972, 250,000 acres produced more than 48,000,000 cwt, with a farm value of over $250 million and a market value exceeding $1.3 billion. Lettuce is available throughout the year and its annual per capita consumption of about 22 lbs is increasing slightly.Of the four types grown commercially in the U.S. - i.e. crisphead (iceberg), butterhead, cos (romaine) and looseleaf, the·crisphead type is the most important. This is the usual "head lettuce" or "iceberg lettuce" found in the market.Lettuce value increases about 10-fold between field and consumer, or approximately 4-fold between shipping point and retail store. Therefore, losses at destination are especially costly and represent not only loss of food but also wastage of all inputs of. labor, energy and materials required for harvesting, packaging, transport, and distribution. A study in the New York area during 1967 to 1969 showed lettuce losses to average 4.1, 4.6, and 7.1% at wholesale, retail, and consumer levels (1). Total loss would presumably approximate the sum of the latter two figures (i.e., 11.7%) and would reflect only quantitative losses.This paper reviews general procedures and practices of handling lettuce and evaluates them in light of commodity requirements and responses; emphasis is on the crisphead type. For a summary of some physical and biological characteristics related to head lettuce see appendix.