Yellow mealworm (Tenebrio molitor L.) represents a highly sustainable source of proteins for food and feed. Industrial production of mealworm meals for food and feed must count on optimized processing methods based on a deep knowledge of nutritional and quality aspects. Viable mealworm larvae (VL) were frozen at −20 °C and dried under two different thermal conditions, namely high-temperature-short-time (HTST, 90 °C for 1.5 h) and low-temperature-long-time (LTLT, 50 °C for 62 h). Proximate composition, fatty acid analyses by gas-chromatography and metabolic profiling by means of proton nuclear magnetic resonance (¹H NMR) spectroscopy were carried out and ¹H NMR data investigated with multivariate data analysis (MVDA). While fatty acid profiles did not indicate significant differences among treatments, ¹H NMR highlighted relevant molecular alterations associated to LTLT drying (95% of detected metabolites are altered by LTLT). In particular, detrimental hydrolysis of triacylglycerols (TAG) was favored during LTLT drying (approximately 25% reduction of TAG in LTLT compared to VL), accompanied by the enrichment of the free amino acid pool. Larvae composition was only minimally affected by the freezing process, with only 15% of the metabolite pool affected.

Industrial relevance

Sustainable industrial production of insect-derived products (insect meal, oil, and other extracts) must count on efficient processes and high standard quality. Freezing and drying are the most critical processing operations in insect industry, since they can strongly affect the quality of final products. It is demonstrated here that low-temperature-long time drying processes negatively affect insect products quality, while freezing and high-temperature-short time drying do not have a significant impact. Molecular details of nutrient degradation processes are provided.

中文翻译：

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冷冻和干燥工艺对食用黄粉虫分子特性的影响

黄粉虫（Tenebrio molitor L.）代表了高度可持续的食品和饲料蛋白质来源。用于食物和饲料的粉虱粉的工业生产必须基于对营养和质量方面的深刻了解而采用优化的加工方法。将活的粉虫幼虫（VL）冷冻在-20°C并在两种不同的热条件下干燥，即高温短时（HTST，90°C持续1.5 h）和低温长时（LTLT， 50°C持续62 h）。通过质子核磁共振（¹ H NMR）光谱进行了近似的组成，气相色谱法的脂肪酸分析和代谢谱分析，结果¹用多变量数据分析（MVDA）研究1 H NMR数据。尽管脂肪酸谱没有显示处理之间的显着差异，但¹ H NMR强调了与LTLT干燥相关的相关分子变化（95％的检测到的代谢物被LTLT改变）。特别地，在LTLT干燥期间有利于三酰基甘油（TAG）的有害水解（与VL相比，LTLT中TAG降低约25％），同时伴随着游离氨基酸池的富集。冷冻过程对幼虫组成的影响很小，只有15％的代谢产物受到影响。

行业相关性

昆虫衍生产品（昆虫粉，油和其他提取物）的可持续工业生产必须依靠高效的过程和高标准的质量。冷冻和干燥是昆虫工业中最关键的加工操作，因为它们会严重影响最终产品的质量。在此证明，低温长时间干燥过程对昆虫产品的质量有负面影响，而冷冻和高温短时间干燥则没有明显的影响。提供了营养物质降解过程的分子细节。