The assessment of the quality of fresh-cut apple slices is important for processing, storage, market value, and consumption. Determination of polyphenol oxidase activity (PPO) in apples is critical for controlling the quality of the final product (i.e., dried apples and juices). Hyperspectral imaging (HSI) is a nondestructive, noncontact, and rapid food quality assessment technique. It has the potential to detect physical and chemical quality attributes of foods such as PPO of apple. The aim of this study was to investigate the suitability of HSI in the visible and near-infrared (VIS-NIR) range for indirect assessment of PPO activity of fresh-cut apple slices. Apple slices of two cultivars (cv. Golden Delicious and Elstar) were used to build a robust detection algorithm, which is independent of cultivars and applied treatments. Partial least squares (PLS) regression using the 7-fold cross-validation method and method comparison analysis (Bland–Altman plot, Passing–Bablok regression, and Deming regression) were performed. The 95% confidence interval (CI) bands for the Bland–Altman analysis between the methods were −4.19 and 13.11, and the mean difference was 3.7e⁻¹². The Passing–Bablok regression had a slope of 0.8 and an intercept of 7.6. The slope of the Deming regression was 0.8 within the CI bands of 0.56 and 1.10. These results show acceptable performance and no significant deviation from linearity. Hence, the results demonstrated the feasibility of HSI as an indirect alternative to the standard chemical analysis of PPO enzyme activity.

中文翻译：

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鲜切苹果切片的高光谱成像与化学分析的比较

鲜切苹果片的质量评估对于加工，存储，市场价值和消费而言非常重要。苹果中多酚氧化酶活性（PPO）的测定对于控制最终产品（即苹果干和果汁）的质量至关重要。高光谱成像（HSI）是一种无损，非接触，快速的食品质量评估技术。它具有检测苹果PPO等食品的物理和化学质量属性的潜力。这项研究的目的是调查在可见和近红外（VIS-NIR）范围内的HSI是否适合间接评估鲜切苹果切片的PPO活性。苹果切片使用两个品种（cv。Golden Delicious和Elstar）来构建鲁棒的检测算法，该算法独立于品种和应用处理。使用7倍交叉验证方法和方法比较分析（Bland–Altman图，Passing–Bablok回归和Deming回归）进行了偏最小二乘（PLS）回归。两种方法之间进行Bland–Altman分析的95％置信区间（CI）带为−4.19和13.11，平均差为3.7。e ^-12。Passing-Bablok回归的斜率为0.8，截距为7.6。在0.56和1.10的CI区间内，戴明回归的斜率是0.8。这些结果显示出可接受的性能，并且线性度无明显偏差。因此，结果证明了HSI作为PPO酶活性标准化学分析的间接替代方法的可行性。