Thermally induced dynamical and structural changes in lactose – maltodextrin system: insights from neutron scattering, thermal analysis and Raman spectroscopy

IF 5.8 2区农林科学 Q1 ENGINEERING, CHEMICAL

Journal of Food Engineering Pub Date : 2025-06-13 DOI:10.1016/j.jfoodeng.2025.112697

Magdalena Witek , Matthew Krzystyniak , Teresa Witczak , Svemir Rudić , Matei Pascariu , Marta Liszka-Skoczylas

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引用次数: 0

Abstract

Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and Raman spectroscopy, augmented by neutron transmission (NT) and Compton scattering (NCS), were employed to investigate thermally-induced changes in local structure and dynamics in the amorphous and crystalline matrix in a lactose, maltodextrin and lactose-maltodextrin mixture.

Incubation at low relative humidity (33 %) produced a dehydrated sample containing a crystalline form of lactose characterised by enhanced thermal stability, as confirmed by DSC and TGA. Strikingly, these structural changes were accompanied by unaltered local dynamics, as characterised by the widths of hydrogen nuclear momentum distribution (NMD widths) obtained from the NCS.

Under higher humidity conditions (65 %), deviations in the shapes of the NT curves from the prediction of the Average Functional Group Approximation (AFGA) indicated melting of lactose crystallites above 120 °C in a lactose-maltodextrin mixture, which was also supported by DSC. Moreover, the constant stoichiometry inferred from the NCS confirmed the absence of sample decomposition (e.g., caramelization) in this temperature range.

Glass transition upon sample heating above 30 °C was monitored by Raman spectroscopy, DSC, and NCS in a lactose-maltodextrin mixture. Spectral shifts and peak broadening were observed in Raman spectra at the temperature region where DCS detected the glass transition. In the same temperature region, NCS measured NMD widths of protons that the AFGA predictions could perfectly model, indicating that the vibrational density of states lacks contributions from intermolecular vibration due to the loosening of the secondary structure.

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乳糖-麦芽糖糊精体系的热致动力学和结构变化：来自中子散射、热分析和拉曼光谱的见解

采用差示扫描量热法（DSC）、热重分析（TGA）和拉曼光谱，结合中子透射（NT）和康普顿散射（NCS），研究了乳糖、麦芽糖糊精和乳糖-麦芽糖糊精混合物中无定形和结晶基质在热诱导下的局部结构和动力学变化。在低相对湿度（33%）下孵育产生脱水样品，其中含有乳糖的结晶形式，其特征是热稳定性增强，经DSC和TGA证实。引人注目的是，这些结构变化伴随着不变的局部动力学，如从NCS获得的氢核动量分布宽度（NMD宽度）所表征的那样。在较高的湿度条件下（65%），NT曲线形状与平均官能团近似（AFGA）预测的偏差表明乳糖结晶在120°C以上的乳糖-麦芽糖糊精混合物中熔化，DSC也支持这一点。此外，从NCS推断出的恒定化学计量学证实，在该温度范围内没有样品分解（例如焦糖化）。在乳糖-麦芽糊精混合物中，通过拉曼光谱、DSC和NCS监测样品加热到30℃以上时的玻璃化转变。在DCS检测到玻璃化转变的温度区域，在拉曼光谱中观察到光谱位移和峰展宽。在相同的温度区域，NCS测量的质子的NMD宽度可以完美地模拟AFGA预测，这表明由于二级结构的松动，分子间振动对状态的振动密度没有贡献。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Food Engineering 工程技术-工程：化工

CiteScore

11.80

自引率

5.50%

发文量

275

审稿时长

24 days

期刊介绍： The journal publishes original research and review papers on any subject at the interface between food and engineering, particularly those of relevance to industry, including: Engineering properties of foods, food physics and physical chemistry; processing, measurement, control, packaging, storage and distribution; engineering aspects of the design and production of novel foods and of food service and catering; design and operation of food processes, plant and equipment; economics of food engineering, including the economics of alternative processes. Accounts of food engineering achievements are of particular value.