Impact of fortification with white willow (Salix alba) bark on the rheological properties, syneresis and colour of nonfat set-type yoghurt

IF 2.7 2区农林科学 Q3 FOOD SCIENCE & TECHNOLOGY

International Journal of Dairy Technology Pub Date : 2025-12-05 DOI:10.1111/1471-0307.70079

Liwen Zheng, Jean Christophe Jacquier, Niamh Harbourne

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引用次数: 0

Abstract

Background

White willow (Salix alba) is a traditional medicinal plant known for its anti-inflammatory and pain-relieving properties, attributed to its high polyphenol content. Yoghurt can serve as an effective delivery carrier for bioactive compounds to develop health-promoting foods due to its unique network structure.

Aim

This study aimed to investigate the impact of willow bark addition on the rheological properties, syneresis and colour of fortified nonfat yoghurt.

Methods

In this study, a nonfat set-type yoghurt supplemented with different levels (0%, 2%, 5%, and 10%) of willow bark was prepared. Rheological properties of the samples were monitored in situ during fermentation and parameters including storage modulus (G′), loss tangent (tan δ), fracture strain (γ_fracture) and fracture stress (σ_fracture) were measured. In addition, syneresis (% w/w) and colour values including lightness (L*), redness (a*) and yellowness (b*) of the final yoghurt were evaluated.

Major Findings

The results showed no significant differences in the final G′ between the control and samples containing 2% and 5% willow bark (p > 0.05), whereas 10% willow bark significantly reduced the final G′ (p < 0.05) after fermentation (at 42°C). When the nonfat set-type yoghurts were cooled from 42°C to 4°C, G′ increased in a dose-dependent manner with the addition of willow bark. Additionally, the level of syneresis increased in a dose-dependent manner in all willow bark-fortified yoghurt samples. Changes observed in the rheological properties and syneresis levels during and after gel formation could be associated with interactions between milk proteins and polyphenols from willow bark.

Industrial Implications

Overall, these results indicate that the fortification of skim yoghurt with low concentrations of willow bark (2% and 5%) has a relatively minimal impact on the rheological properties and appearance of the product, providing technical insights for functional yoghurt manufacturers.

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白柳树树皮强化对脱脂凝固型酸奶流变特性、合成及色泽的影响

白柳（Salix alba）是一种传统的药用植物，因其高多酚含量而具有抗炎和缓解疼痛的特性。酸奶由于其独特的网状结构，可以作为生物活性化合物的有效载体，开发促进健康的食品。目的研究柳树皮添加量对强化脱脂酸奶流变学特性、合成及色泽的影响。方法制备了添加0%、2%、5%、10%柳皮的脱脂酸奶。对发酵过程中样品的流变特性进行了原位监测，并测量了贮藏模量（G′）、损失切线（tan δ）、断裂应变（γ断裂）和断裂应力（σ断裂）等参数。此外，还对最终酸奶的合成（% w/w）和颜色值进行了评价，包括亮度（L*）、红度（a*）和黄度（b*）。结果表明，对照组与含2%和5%柳皮的样品的最终G′无显著差异（p > 0.05），而含10%柳皮的样品发酵后（42℃）的最终G′显著降低（p < 0.05）。当脱脂酸奶从42°C冷却到4°C时，随着柳树皮的加入，G′呈剂量依赖性增加。此外，在所有柳树皮强化酸奶样品中，协同作用水平以剂量依赖的方式增加。凝胶形成期间和之后的流变学性质和协同作用水平的变化可能与牛奶蛋白和柳树皮多酚之间的相互作用有关。总体而言，这些结果表明，低浓度柳树皮（2%和5%）强化脱脂酸奶对产品流变特性和外观的影响相对较小，为功能性酸奶制造商提供了技术见解。

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

International Journal of Dairy Technology 工程技术-食品科技

CiteScore

7.00

自引率

4.50%

发文量

审稿时长

12 months

期刊介绍： The International Journal of Dairy Technology ranks highly among the leading dairy journals published worldwide, and is the flagship of the Society. As indicated in its title, the journal is international in scope. Published quarterly, International Journal of Dairy Technology contains original papers and review articles covering topics that are at the interface between fundamental dairy research and the practical technological challenges facing the modern dairy industry worldwide. Topics addressed span the full range of dairy technologies, the production of diverse dairy products across the world and the development of dairy ingredients for food applications.