Comparative analysis of citrus fruits for nutraceutical properties

Abstract Fruits and vegetables (F and V) are valuable for their micronutrients, but many F and V in diverse growth areas have not been scientifically validated for these components. The nutraceutical characteristics of the pulp of eight citrus fruits grown in Pakistan were, therefore, investigated. Expectedly, the fruits differed in moisture (86.9-88.9%), ash (0.37-0.53%), pH (2.9-5.8), total soluble solids (8.1-13.7 °Brix), titratable acidity (7.9-13.1%), total sugars (5.1-8.8%), reducing sugars (2.8-4.3%), and non-reducing sugars (0.3-0.5%) contents. Potassium, sodium and magnesium were the major minerals, while iron, zinc and manganese were present in minor fractions in the pulps. Phytochemical analysis (total phenolic content, 132-243 µg/g GAE; total flavonoids content, 4.2-12.1 µg/g QE; vitamin C, 36.3-62.3 mg/100 g) revealed antioxidant potential that was confirmed by a high 1, 1-diphenyl 1-2-picrylhydrazyl (DPPH) radical scavenging activity, showing a highly positive correlation (r2 > 0.921, 0.917, 0.807 p > 0.05) with the measured antioxidant components (Total Phenolics, Total Flavonoids and vitamin C). Principal component analysis shows a significant relationship between the citrus varieties and their quality parameters to guide their industrial potential as sources of nutraceuticals.摘要 果蔬（Fruits and Vegetables，F&V）因富含微量营养素而具备极高应用价值，但全球不同种植产区的诸多果蔬，其所含的此类营养成分尚未得到科学验证。 为此，本研究针对巴基斯坦种植的8种柑橘果实的果肉营养保健特性展开了探究。正如预期所料，供试果实的各项指标存在显著差异：水分含量为86.9%~88.9%、灰分含量为0.37%~0.53%、pH值为2.9~5.8、总可溶性固形物为8.1~13.7 °Brix、可滴定酸度为7.9%~13.1%、总糖含量为5.1%~8.8%、还原糖含量为2.8%~4.3%，非还原糖含量为0.3%~0.5%。 果肉中的主要矿物质成分为钾、钠与镁，而铁、锌及锰的含量相对较低。植物化学分析结果显示，供试柑橘果肉的总酚含量为132~243 μg/g没食子酸当量（Gallic Acid Equivalent，GAE）、总黄酮含量为4.2~12.1 μg/g槲皮素当量（Quercetin Equivalent，QE）、维生素C含量为36.3~62.3 mg/100g，表明其具备抗氧化潜能；该抗氧化活性通过高效的1,1-二苯基-2-苦基肼基（1,1-diphenyl-2-picrylhydrazyl，DPPH）自由基清除活性得到证实，且该清除活性与测定得到的总酚、总黄酮及维生素C含量均呈现高度正相关（决定系数r²分别为0.921、0.917、0.807，p>0.05）。 主成分分析结果表明，不同柑橘品种与其品质参数之间存在显著关联，可为其作为营养保健原料的工业开发潜力提供理论指导依据。