引言
花生（Arachis hypogaea L.）是一种全球重要的油料和经济作物，其种子脂肪含量约为50%–54%，蛋白质含量为23%–26%，富含不饱和脂肪酸以及植物甾醇、生育酚、多酚和白藜芦醇等生物活性化合物（Bodoira等，2022；Machado等，2025）。这些成分具有改善心血管功能、抗氧化和调节血脂等潜在健康效益，使花生成为优质植物蛋白和食用油的宝贵来源（Bodoira等，2022；Hosseini Taheri等，2024；Machado等，2025）。中国是全球最大的花生生产国、消费国和进口国。据美国农业部（USDA）估计，2024/2025年度中国花生产量约占全球总产量的37%，国内消费量达2017万吨，凸显其在食品加工、制油和休闲食品行业中重要的经济和战略意义。 freshly harvested peanut pods typically have a moisture content as high as 45%–60% (Zhou et al., 2025). During field stacking or storage, such high moisture levels readily induce germination and fungal proliferation, particularly leading to aflatoxin contamination, which severely compromises both food safety and commercial quality (Zhou et al., 2025). Previous studies have demonstrated that reducing pod moisture content to 8%–10% effectively inhibits fungal metabolic activity and minimizes the risk of aflatoxin contamination to the greatest extent (Yang et al., 2025a; Yang et al., 2025b). Consequently, drying constitutes a critical postharvest processing step for ensuring quality preservation and minimizing losses in peanut production.
Mechanical drying plays an important role in mitigating post-harvest losses caused by mould infestation in peanuts, as it eliminates the uncertainties associated with weather-dependent natural drying. Nevertheless, the high energy consumption and severe drying conditions commonly associated with mechanical drying often compromise peanut quality, posing a significant challenge to its practical application. Among the various mechanical drying techniques, hot air drying remains the most widely adopted; however, it is characterised by high energy demand, low thermal efficiency, and a marked tendency to induce quality degradation, including protein denaturation and lipid oxidation (Guo et al., 2026). Heat pump drying (HPD) is an energy-efficient and environmentally friendly option, recovers exhaust heat to enable low energy use, precise control, and mild conditions; however, rapid surface evaporation can cause crust formation, hinder internal moisture transport and slow the later-stage drying rate. Far-infrared (FIR) drying, in contrast, uses volumetric radiation to provide uniform heating and enhanced internal diffusion, yet it suffers from poor low-temperature efficiency, higher energy consumption, and a risk of localized overheating if poorly regulated (Ta?eri et al., 2018; Zhu et al., 2024, Zhu et al., 2024; Miao et al., 2025; Zhang, Lu, et al., 2024).
Meanwhile, combined drying techniques have attracted growing interest for their potential to enhance drying efficiency and product quality. Recent studies have demonstrated the effectiveness of such strategies across various drying systems. In infrared-related applications, Xu et al. (2025) reported that far-infrared radiation-assisted pulsed vacuum freeze-drying significantly improved the quality of banana slices, while Xu et al., 2022a, Xu et al., 2022b found that far-infrared combined with hot air drying reduced drying time and enhanced the retention of colour, aroma, and bioactive compounds in Anoectochilus roxburghii. Similar benefits have also been observed in solar drying, where hybrid photovoltaic-thermal and IoT-assisted systems notably improved drying kinetics, moisture diffusivity, and quality preservation, with substantial economic advantages (Elwakeel et al., 2025; Khater et al., 2026). Collectively, these findings highlight the considerable promise of combined drying strategies. Given that HPD and FIR are complementary in nature, with HPD excelling in energy-efficient convective moisture removal and FIR specializing in volumetric internal heating, their combination offers a promising strategy to overcome the limitations of each individual technology. Therefore, in the present study, we aim to integrate HPD with FIR and systematically investigate the effects of this combined approach on the drying characteristics, moisture migration, and nutritional quality of peanuts.
Fresh in-shell peanuts were selected as the raw material in this study, with natural air drying (NAD), sole heat pump drying (HPD), and sole far-infrared (FIR) drying designated as the control groups. The combined HPD-FIR drying approach was systematically evaluated in terms of its effects on drying kinetics, appearance color, texture properties, nutritional quality (including fat, protein, and fatty acid profiles), and microstructural characteristics. In addition, the possible drying mechanism of this combined method and its practical applicability for peanut processing were investigated. The results are expected to offer both a theoretical foundation and a technical reference for achieving energy-efficient, high-quality drying of peanuts and other similar oilseed crops.
