Mehany Taha, González-Sáiz José M, Pizarro Consuelo
Department of Chemistry, University of La Rioja, 26006 Logroño, Spain.
Foods. 2025 Jan 15;14(2):260. doi: 10.3390/foods14020260.
This study explores approaches to enhancing the biostability of extra virgin olive oil (EVOO) supplemented with olive fruit extract (OFE) enriched with hydroxytyrosol (HTyr). The investigation focuses on prolonged deep frying (DF) conditions at 170 °C and 210 °C, over durations ranging from 3 to 48 h, with the aim of improving sensorial attributes, polyphenolic content, and thermal oxidative stability. Parameters, such as acidity, peroxide value (PV), K, K, ΔK, phenolic compounds, and sensory attributes, were monitored. The PV did not exceed the standard limit in HTyr-EVOO at 210 °C/24 h; however, in non-supplemented EVOOs, it remained within the limits only up to 210 °C/18 h. Acidity stayed within the acceptable limit (≤0.8) at 170 °C/24 h in both enriched and non-enriched EVOOs. K values were ≤2.5 in HTyr-EVOO fried at 170 °C/18 h. K and ΔK did not exceed the limits in HTyr-EVOO at 170 °C/3 h, whereas they surpassed them in non-supplemented oils. Additionally, HTyr and tyrosol levels were significantly higher ( < 0.05) in HTyr-EVOOs. Phenolic compounds, including verbascoside, pinoresinol, 1-acetoxypinoresinol, and phenolic acids, such as chlorogenic, vanillic, homovanillic, 4-dihydroxybenzoic, and caffeic acids, were detected in HTyr-EVOOs. Oxidized secoiridoid derivatives increased significantly as DF progressed. Moreover, sensory analysis revealed that positive attributes in EVOOs-such as fruity, bitter, and pungent notes-decreased significantly with increasing temperature and frying duration ( < 0.05). Beyond 210 °C/6 h, these attributes were rated at zero. However, HTyr-EVOOs exhibited lower rancidity compared to non-enriched oils under identical conditions, attributed to the protective effect of HTyr. In conclusion, HTyr-EVOOs demonstrated thermal stability up to 210 °C/6 h, retaining desirable sensory qualities, higher phenolic content, and reduced degradation. These findings indicate that natural OFEs have strong potential as food additive in deep fried EVOOs, enhancing sensory properties, health benefits, and overall oil stability. This innovation provides a practical solution for the food industry by improving the biostability and versatility of EVOO. Further research is recommended to investigate various EVOO categories and oils from diverse origins.
本研究探索了增强添加富含羟基酪醇（HTyr）的橄榄果提取物（OFE）的特级初榨橄榄油（EVOO）生物稳定性的方法。研究重点关注在170℃和210℃下持续3至48小时的长时间油炸（DF）条件，目的是改善感官特性、多酚含量和热氧化稳定性。监测了酸度、过氧化值（PV）、K、K、ΔK、酚类化合物和感官特性等参数。在210℃/24小时的条件下，HTyr-EVOO中的PV未超过标准限值；然而，在未添加的EVOO中，仅在210℃/18小时内保持在限值范围内。在170℃/24小时时，添加和未添加的EVOO中的酸度均保持在可接受限值（≤0.8）内。在170℃/18小时油炸的HTyr-EVOO中，K值≤2.5。在170℃/3小时时，HTyr-EVOO中的K和ΔK未超过限值，而在未添加的油中则超过了限值。此外，HTyr-EVOO中的HTyr和酪醇水平显著更高（<0.05）。在HTyr-EVOO中检测到了酚类化合物，包括毛蕊花糖苷、松脂醇、1-乙酰氧基松脂醇以及酚酸，如绿原酸、香草酸、高香草酸、4-二羟基苯甲酸和咖啡酸。随着油炸时间的延长，氧化的裂环烯醚萜衍生物显著增加。此外，感官分析表明，EVOO中的正面特性，如果香、苦味和辛辣味，随着温度和油炸时间的增加而显著降低（<0.05）。超过210℃/6小时后，这些特性的评分为零。然而，在相同条件下，与未添加的油相比，HTyr-EVOO的酸败程度更低，这归因于HTyr的保护作用。总之，HTyr-EVOO在高达210℃/6小时的条件下表现出热稳定性，保留了理想的感官品质、更高的酚类含量并减少了降解。这些发现表明，天然OFE作为油炸EVOO中的食品添加剂具有很大潜力，可增强感官特性、健康益处和整体油的稳定性。这一创新为食品工业提供了一个切实可行的解决方案，通过提高EVOO的生物稳定性和多功能性。建议进一步研究调查各种EVOO类别和不同产地的油。
