Department of Nutrition and Metabolism, National Institutes of Biomedical Innovation, Health and Nutrition.
Faculty of Sports and Health Science, Hosei University.
J Nutr Sci Vitaminol (Tokyo). 2020;66(5):441-448. doi: 10.3177/jnsv.66.441.
The official testing methods for establishing nutritive values are accurate but relatively costly and time-consuming. Near infrared spectroscopy (NIRS) is potentially an alternative method that can analyze several components in a few minutes using an exclusively electronic instrument with no need for a laboratory expert. However, the accuracy of commercial NIRS spectroscopic food analyzers is not sufficient for Japanese food labeling, because of interference from moisture contained in the foods. This study aims to assess the effect of a freeze-drying pretreatment on the accuracy of NIRS food analysis. Thirty-four samples, consisting of six food items habitually consumed in Japan and cooked by different cooking methods were treated by milling then freeze-drying. They were analyzed by a commercial NIRS instrument (Calorie Answer) with calibration curves developed based on other freeze-dried samples. The obtained nutritive values (energy, protein, lipid, carbohydrate and moisture) were corrected to the values before freeze-drying using the vaporized moisture content. The same samples before freeze-drying were also analyzed using the official testing methods to assess the analytical accuracy using NIRS after freeze-drying, and further analyzed using the same NIRS with the commercial calibration curves to assess the effect of freeze-drying. The accuracies were better for the freeze-dried samples than for the wet samples. The magnitude of the error in energy and carbohydrate was significantly associated with the retained moisture content in the freeze-dried sample. In conclusion, freeze-drying was an effective pretreatment for improving the accuracy of NIRS analyses of Japanese cooked foods, although it is still time-consuming and needs additional investment.
建立营养价值的官方测试方法准确，但相对昂贵且耗时。近红外光谱（NIRS）是一种潜在的替代方法，它可以使用专门的电子仪器在几分钟内分析多种成分，而无需实验室专家。然而，由于食品中所含水分的干扰，商业 NIRS 光谱食品分析仪的准确性对于日本食品标签来说还不够。本研究旨在评估冷冻干燥预处理对 NIRS 食品分析准确性的影响。34 个样本，包括六种在日本习惯性食用的食品，并采用不同的烹饪方法进行烹饪，经过研磨和冷冻干燥处理。它们使用商业 NIRS 仪器（Calorie Answer）进行分析，该仪器基于其他冷冻干燥样本开发了校准曲线。通过蒸发水分含量将获得的营养价值（能量、蛋白质、脂质、碳水化合物和水分）校正为冷冻干燥前的值。还使用官方测试方法分析了未经冷冻干燥的相同样本，以评估冷冻干燥后使用 NIRS 的分析准确性，并使用相同的 NIRS 和商业校准曲线进一步分析，以评估冷冻干燥的效果。冷冻干燥样品的准确性优于湿样品。能量和碳水化合物的误差幅度与冷冻干燥样品中保留的水分含量显著相关。总之，冷冻干燥是提高 NIRS 分析日本烹饪食品准确性的有效预处理方法，尽管它仍然耗时且需要额外的投资。
