J Acad Nutr Diet. 2018 Aug;118(8):1482-1489. doi: 10.1016/j.jand.2018.02.002. Epub 2018 Apr 12.
Scientifically sound methods for investigating dietary consumption patterns from self-serve salad bars are needed to inform school policies and programs.
To examine the reliability and validity of digital imagery for determining starting portions and plate waste of self-serve salad bar vegetables (which have variable starting portions) compared with manual weights.
DESIGN/METHODS: In a laboratory setting, 30 mock salads with 73 vegetables were made, and consumption was simulated. Each component (initial and removed portion) was weighed; photographs of weighed reference portions and pre- and post-consumption mock salads were taken. Seven trained independent raters visually assessed images to estimate starting portions to the nearest ¼ cup and percentage consumed in 20% increments. These values were converted to grams for comparison with weighed values.
Intraclass correlations between weighed and digital imagery-assessed portions and plate waste were used to assess interrater reliability and validity. Pearson's correlations between weights and digital imagery assessments were also examined. Paired samples t tests were used to evaluate mean differences (in grams) between digital imagery-assessed portions and measured weights.
Interrater reliabilities were excellent for starting portions and plate waste with digital imagery. For accuracy, intraclass correlations were moderate, with lower accuracy for determining starting portions of leafy greens compared with other vegetables. However, accuracy of digital imagery-assessed plate waste was excellent. Digital imagery assessments were not significantly different from measured weights for estimating overall vegetable starting portions or waste; however, digital imagery assessments slightly underestimated starting portions (by 3.5 g) and waste (by 2.1 g) of leafy greens.
This investigation provides preliminary support for use of digital imagery in estimating starting portions and plate waste from school salad bars. Results might inform methods used in empirical investigations of dietary intake in schools with self-serve salad bars.
需要科学合理的方法来调查自助沙拉吧的饮食消费模式，以为学校政策和项目提供信息。
与手动称重相比，研究数字图像在确定自助沙拉吧蔬菜（起始份量不同）的起始份量和餐盘浪费方面的可靠性和有效性。
设计/方法：在实验室环境中，制作了 30 份模拟沙拉，其中有 73 种蔬菜，并进行了模拟食用。每个组成部分（初始和移除部分）都进行称重；对称重参考部分以及食用前后的模拟沙拉进行拍照。由 7 名经过培训的独立评审员进行图像评估，以估计起始份量的最接近四分之一杯，并以 20%的增量估计消耗的百分比。这些值转换为克，与称重值进行比较。
使用 weighed 和 digital imagery-assessed 份量和餐盘浪费之间的组内相关系数来评估评分者间的可靠性和有效性。还检查了重量和数字图像评估之间的 Pearson 相关系数。使用配对样本 t 检验评估数字图像评估与实测重量之间的平均差异（以克为单位）。
数字图像的起始份量和餐盘浪费的评分者间可靠性很高。在准确性方面，组内相关系数为中等，与其他蔬菜相比，确定绿叶蔬菜的起始份量的准确性较低。然而，数字图像评估的餐盘浪费准确性很高。数字图像评估在估计总体蔬菜起始份量或浪费方面与实测重量没有显著差异；然而，数字图像评估略微低估了绿叶蔬菜的起始份量（3.5 克）和浪费量（2.1 克）。
本研究初步支持在学校沙拉吧中使用数字图像来估计起始份量和餐盘浪费。研究结果可能为使用自助沙拉吧的学校饮食摄入实证研究提供方法依据。
