Faculty of Engineering, Grupo de Investigación en Procesos Agroindustriales, Universidad de La Sabana, Campus Universitario del Puente del Común, Km. 7 Autopista Norte de Bogotá, Chía, Cundinamarca, Colombia.
Departamento de Ingeniería Bioquímica, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Plan de Ayala y Carpio S/N, CP, 11340, CDM, México.
J Food Sci. 2020 Jun;85(6):1805-1814. doi: 10.1111/1750-3841.15130. Epub 2020 Jun 4.
Papaya fruit, widely consumed around the world, is mechanically and structurally affected by several enzymatic processes during ripening, where pectin methylesterase plays a key role. Hence, the aim of this work was to evaluate possible correlations among physicochemical changes, mechanical parameters, viscoelastic behavior, and enzyme activity of pectin methylesterase to provide information about the softening phenomenon by applying the Maxwell and Peleg models. Mechanical parameters were estimated by texture profile analysis, enzyme activity by Michaelis-Menten parameters, and viscoelastic behavior by relaxation test responses fitted to these models. The Maxwell model described properly mechanical changes during ripening, displaying a better adjustment (R > 0.97) than the Peleg model (0.80 < R < 0.84). Pearson correlation analysis (P ≤ 0.01) indicated an inversely proportional relation among firmness, total soluble solids, and the first elastic element of the Maxwell model. Besides, the PME Michaelis-Menten affinity constant showed a correlation between the first elastic element and the first viscoelastic element of the Maxwell model. Findings of this work pointed out that the first Maxwell elastic element could explain structural changes as papaya ripening advance, associated with pectin methylesterase activity, cell wall disruption, and cell assembling into the tissue. PRACTICAL APPLICATION: Mechanical and viscoelastic behavior of papaya fruit tissue were described by the Maxwell model associating both viscous and elastic elements to the softening process. The results provide background and practical knowledge to describe structural changes during the ripening process of papaya depending on its enzymatic activity. Outcomes could be further applied to understand changes in other fruits or food matrixes that soften during postharvest, storage, and food chain supply processes.
番木瓜果实是世界范围内广泛消费的水果，在成熟过程中会受到几种酶促过程的机械和结构影响，其中果胶甲酯酶起着关键作用。因此，本工作旨在评估果胶甲酯酶的理化变化、力学参数、黏弹性行为和酶活性之间的可能相关性，通过应用 Maxwell 和 Peleg 模型提供有关软化现象的信息。通过质构分析估计力学参数，通过 Michaelis-Menten 参数估计酶活性，通过松弛试验响应拟合这些模型来估计黏弹性行为。Maxwell 模型能够很好地描述成熟过程中的力学变化，其调整效果优于 Peleg 模型（0.80<R<0.84）（R>0.97）。Pearson 相关分析（P≤0.01）表明硬度、总可溶性固形物与 Maxwell 模型的第一弹性元件之间呈反比关系。此外，PME Michaelis-Menten 亲和常数与 Maxwell 模型的第一弹性元件和第一黏弹元件之间存在相关性。本研究结果表明，随着番木瓜果实的成熟，第一 Maxwell 弹性元件可以解释结构变化，这与果胶甲酯酶活性、细胞壁破裂和细胞组织组装有关。实际应用：番木瓜果实组织的力学和黏弹性能通过 Maxwell 模型进行描述，该模型将黏性和弹性元件与软化过程相关联。这些结果为描述番木瓜成熟过程中的结构变化提供了背景和实践知识，这取决于其酶活性。研究结果可以进一步应用于理解其他在收获后、储存和食品供应链过程中软化的水果或食品基质的变化。
