Aktas Ayse Burcu, Grassi Silvia, Picozzi Claudia, Alamprese Cristina
Department of Biochemistry, Faculty of Science, Sivas Cumhuriyet University, 58140 Sivas, Turkey.
Department of Food, Environmental and Nutritional Sciences (DeFENS), Università degli Studi di Milano, 20133 Milan, Italy.
Foods. 2025 Jun 11;14(12):2053. doi: 10.3390/foods14122053.
Yogurt fortification with purslane ( L.) can improve its health benefits, but it may alter the fermentation step and its final properties. Thus, the current study investigated the suitability of Fourier Transform-Near Infrared (FT-NIR) spectroscopy for in-line monitoring of lactic acid fermentation of purslane-fortified yogurt compared with fundamental rheology. Changes in the yogurt properties during storage were also assessed. Set-type yogurts without and with lyophilized purslane leaves (0.55%) were produced and stored at 4 °C for up to 18 days. Lactic acid bacteria concentrations before and after fermentation at 43 °C for 2.5 h showed that the presence of purslane did not interfere with bacterial growth. The purslane addition increased the milk viscosity, resulting in a yogurt with complex modulus values higher than those of the reference sample (360 vs. 172 Pa). The elaboration of spectral data with Principal Component Analysis and the Gompertz equation enabled calculation of the kinetic critical points. Applying the Gompertz equation to the rheological data, it was evident that FT-NIR spectroscopy detected earlier the fermentation progression (the critical times were about 18% earlier on average), thus enabling better control of yogurt production. No significant changes in microbial or textural properties were noted during yogurt storage, demonstrating that purslane addition did not affect the product stability.
用马齿苋强化酸奶可以提高其健康益处，但可能会改变发酵步骤及其最终特性。因此，本研究调查了傅里叶变换近红外（FT-NIR）光谱法与基础流变学相比，用于在线监测马齿苋强化酸奶乳酸发酵的适用性。还评估了酸奶在储存期间的性质变化。制作了不含和含有冻干马齿苋叶（0.55%）的凝固型酸奶，并在4℃下储存长达18天。在43℃下发酵2.5小时前后的乳酸菌浓度表明，马齿苋的存在不会干扰细菌生长。添加马齿苋增加了牛奶的粘度，使得酸奶的复数模量值高于参考样品（360对172Pa）。用主成分分析和Gompertz方程处理光谱数据能够计算动力学临界点。将Gompertz方程应用于流变学数据，很明显FT-NIR光谱法能更早地检测到发酵进程（平均临界时间早约18%），从而能够更好地控制酸奶生产。在酸奶储存期间，未观察到微生物或质地特性有显著变化，表明添加马齿苋不会影响产品稳定性。
