Department of Consumer Science, University of the Free State, Bloemfontein, Free State, South Africa.
Agricultural Research Council Animal Production, Irene, Gauteng, South Africa.
PLoS One. 2020 Aug 17;15(8):e0237517. doi: 10.1371/journal.pone.0237517. eCollection 2020.
Climate change, limited water resources and expected population increases would require crops which contribute toward more resilient, more productive, more sustainable and climate-smart food systems. The cactus pear is a drought-resistant and sustainable food source to humans and livestock alike. Cactus mucilage has multiple applications in the food and packaging industry. It is eco-friendly, economical, functional and has multiple health benefits. However, the researchers observed umpteen variations in extracted mucilage yield and viscosity every time the cladodes were harvested, making the standardisation of formulations troublesome. We aimed to examine the effect of weather conditions on the physicochemical characteristics of cactus pear cladodes and mucilage extracted over two seasons to understand these observed variations in mucilage characteristics. Forty cladodes, ten from each of Opuntia ficus-indica Algerian, Morado and Gymno-Carpo and Opuntia robusta Robusta were harvested every month from February to August in Bloemfontein, South Africa. Daily weather data were obtained, weight and moisture contents determined on cladodes and yield, viscosity, pH, conductivity and malic acid content determined on extracted mucilage. Pearson correlation coefficients were calculated between the weather conditions, cladode properties, and mucilage properties. Contrary to common belief, neither increasing cladode weight as they grow, nor rainfall were the leading causes of mucilage inconsistencies. However, the correlations showed a relationship between environmental temperatures, cladode pH and conductivity, and mucilage viscosity and yields. In hot summer weather, the pH was lower, which led to an abundance of positive ions in cladodes. The H+ ions neutralise the negative charges along the outstretched mucilage molecule, causing it to coil up, reducing the viscosity of the mucilage. Thus, environmental temperatures rather than rainfall or cladode maturity influenced the physicochemical characteristics of mucilage. The findings should make an essential contribution in predicting the physicochemical characteristics of mucilage for specific food-related functions by observing the weather conditions.
气候变化、有限的水资源和预计的人口增长将要求作物具有更强的弹性、更高的生产力、更可持续和更智能的粮食系统。仙人掌是一种耐旱的可持续人类和牲畜食物来源。仙人掌胶具有多种在食品和包装行业中的应用。它是环保、经济、功能多样，并且具有多种健康益处。然而，研究人员每次收获仙人掌时都观察到提取胶产量和粘度存在无数变化，这使得配方的标准化变得麻烦。我们旨在研究天气条件对仙人掌茎和提取胶的物理化学特性的影响，以了解胶特性的这些观察到的变化。在南非布隆方丹，从 2 月到 8 月，每月从 Opuntia ficus-indica 阿尔及利亚、Morado 和 Gymno-Carpo 和 Opuntia robusta Robusta 中收获 40 个仙人掌，每个品种 10 个。每天获取天气数据，测定仙人掌的重量和水分含量，并测定提取胶的产量、粘度、pH 值、电导率和苹果酸含量。计算了天气条件、仙人掌特性和胶特性之间的皮尔逊相关系数。与普遍看法相反，随着仙人掌的生长，增加仙人掌的重量或降雨量并不是胶不一致的主要原因。然而，相关性表明环境温度、仙人掌 pH 值和电导率与胶粘度和产量之间存在关系。在炎热的夏季天气中，pH 值较低，导致仙人掌中阳离子数量增加。H+离子中和伸展胶分子上的负电荷，使其卷曲，从而降低胶的粘度。因此，环境温度而不是降雨量或仙人掌成熟度影响胶的物理化学特性。这些发现应该通过观察天气条件，对特定与食品相关的功能预测胶的物理化学特性做出重要贡献。
