Storage stability of crispy pork rind and rancidity prediction by near infrared spectroscopy and PLSR models

• Nitrogen flushing extended the shelf life of crispy pork rind by 4-20% • Fresh oil improved initial product quality, but benefit fades during storage • NIR spectroscopy enabled rapid prediction of peroxide, anisidine and Totox value • Self-organizing map classification identified rancid samples with 73% accuracy The storage stability of crispy pork rind, a widely consumed snack, is influenced by factors such as frying oil type and packaging conditions. We examined the impact of frying with new versus reused oil and compared storage stability under ambient air and nitrogen packaging. This study employed near infrared (NIR) spectroscopy to evaluate these effects and predict oxidative compounds using partial least squares regression (PLSR). The study found that while frying in new oil initially improved product quality, this advantage diminished over time. In contrast, packaging played a more crucial role, with nitrogen-packed samples showing greater stability - extending shelf life by 4–20% compared with those stored in ambient air. The improved stability is attributed to nitrogen's ability to displace oxygen, thereby reducing oxidative rancidity regardless of the oil’s initial condition. The PLSR models achieved high accuracy for predicting lipid oxidation, i.e., peroxide, anisidine, and Totox values (R>0.82, RMSE≤0.75, RPD>2.22). Furthermore, self-organizing map (SOM) classification achieved 73% accuracy in distinguishing new and rancid crispy pork rind. These findings establish NIR spectroscopy as a reliable method for both quantitative and qualitative assessment of rancidity in crispy pork rind; however, different pork types and packaging conditions should be further examined.