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Wang C, Cui Q, Liu Q, Fan Y, Li Q, Zhao M, Zhao L, Zhang J, Rao G. Analysis of heaping-induced decline in olive quality: insights from integrated analysis between phenotypic traits and gene expression profiles. TREE PHYSIOLOGY 2024; 44:tpae066. [PMID: 38861416 DOI: 10.1093/treephys/tpae066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 05/09/2024] [Accepted: 06/10/2024] [Indexed: 06/13/2024]
Abstract
Heaping is an unavoidable process before olive milling, and its duration significantly affects the olive quality. However, there is limited research on the quality changes of olive fruits on a short-time scale. To gain a better understanding of the molecular mechanisms underlying postharvest deterioration of olives, this study piled olives at room temperature and extracted oil at 0, 8, 24, 48 and 72 h to analyze oil quality parameters. Gas/Liquid Chromatography-Mass Spectrometry (GC/LC-MS) techniques were employed to investigate variations in metabolite contents. Concurrently, the transcriptional profiles of olives during heaping were examined. As piling time progressed, quality indicators declined, and stored fruit were categorized into three groups based on their quality characters: '0 h' belongs to the first category, '8 h' and '24 h' to the second category, and '48 h' and '72 h' to the third category. Metabolite changes were consistent with the expression patterns of genes related to their synthesis pathways. Additionally, ethylene was identified as a crucial factor influencing fruit senescence. These findings establish a foundation for further research on olive deterioration after harvesting and offer insights for optimizing olive oil production.
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Affiliation(s)
- Chenhe Wang
- State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Xiangshan road, Haidian district, Beijing 100091, China
- Collaborative Innovation Center of Sustainable Forestry in Southern China, Nanjing Forestry University, Longpan road, Xuanwu district, Nanjing 210037, China
| | - Qizhen Cui
- State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Xiangshan road, Haidian district, Beijing 100091, China
- Collaborative Innovation Center of Sustainable Forestry in Southern China, Nanjing Forestry University, Longpan road, Xuanwu district, Nanjing 210037, China
| | - Qingqing Liu
- State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Xiangshan road, Haidian district, Beijing 100091, China
- Collaborative Innovation Center of Sustainable Forestry in Southern China, Nanjing Forestry University, Longpan road, Xuanwu district, Nanjing 210037, China
| | - Yutong Fan
- State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Xiangshan road, Haidian district, Beijing 100091, China
- Collaborative Innovation Center of Sustainable Forestry in Southern China, Nanjing Forestry University, Longpan road, Xuanwu district, Nanjing 210037, China
| | - Qiaohua Li
- Longnan Xiangyu Olive Development Co., Ltd, Hanwang road, Wudu district, Longnan, Gansu, 746000, China
| | - Min Zhao
- Longnan Xiangyu Olive Development Co., Ltd, Hanwang road, Wudu district, Longnan, Gansu, 746000, China
| | - Liangmei Zhao
- Longnan Xiangyu Olive Development Co., Ltd, Hanwang road, Wudu district, Longnan, Gansu, 746000, China
| | - Jianguo Zhang
- State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Xiangshan road, Haidian district, Beijing 100091, China
- Collaborative Innovation Center of Sustainable Forestry in Southern China, Nanjing Forestry University, Longpan road, Xuanwu district, Nanjing 210037, China
- Key Laboratory of Tree Breeding and Cultivation, National Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Xiangshan road, Haidian district, Beijing 100091, China
| | - Guodong Rao
- State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Xiangshan road, Haidian district, Beijing 100091, China
- Collaborative Innovation Center of Sustainable Forestry in Southern China, Nanjing Forestry University, Longpan road, Xuanwu district, Nanjing 210037, China
- Key Laboratory of Tree Breeding and Cultivation, National Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Xiangshan road, Haidian district, Beijing 100091, China
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2
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Antonelli S, Pozas S, Saavedra-Torrico J, Donders M, Bustamante C, Sepúlveda B, Tapia F, García-González DL, Romero N. The Management of Irrigation and Potassium Fertilization to Mitigate the Effect of Light Frosts on the Phenolic and Volatile Compounds in Virgin Olive Oils. Antioxidants (Basel) 2024; 13:559. [PMID: 38790663 PMCID: PMC11117877 DOI: 10.3390/antiox13050559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Revised: 04/11/2024] [Accepted: 04/24/2024] [Indexed: 05/26/2024] Open
Abstract
The frequency of early frosts has increased in recent years, which are injurious to olive growing, causing losses in the yield and quality of virgin olive oil. In this research, it was studied how the management of agronomic factors mitigates frost damage in Arbequina olives, minimizing the loss of phenols and volatiles in virgin olive oil, at different fruit ripening stages. A Box-Behnken design and multivariate analysis were performed, with three levels of irrigation, potassium fertilization, and foliar copper application (15 treatments). Virgin olive oil was extracted from fresh and frozen olives. Light frost caused a significant decrease in the total phenols and secoiridoid compounds in and the antioxidant capacity of the frost-affected oils, which were perceived as more pungent and had the slight defect of "frostbitten olives". According to the Box-Behnken design, an 86% reference evapotranspiration (ET0) or higher with 100 potassium oxide units (UK2O) and a 100% ET0 or higher with 250 UK2O would be required to minimize the effect of light frost on phenols and volatiles. Partial Least Squares Regression-Discriminant Analysis (PLS-DA) differentiated the virgin olive oils according to their ripening stage and fresh and frost conditions. Moreover, PLS-DA positively correlated a 75-100% ET0 and 0 Uk2O with the dialdehydic form of the decarboxymethyl ligstroside aglycone (p-HPEA-EDA), the dialdehydic form of the decarboxymethyl oleuropein aglycone (3,4-DHPEA-EDA), the dialdehydic form of the ligstroside aglycone (p-HPEA-EDA-DLA), and with fruity, pungent, and bitter attributes. Precision agronomic management based on the needs of the crop itself would avoid unnecessary stress on olive trees and oil damage.
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Affiliation(s)
- Suony Antonelli
- Departamento de Ciencia de los Alimentos y Tecnología Química, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago 8380000, Chile; (S.A.); (S.P.)
| | - Sebastián Pozas
- Departamento de Ciencia de los Alimentos y Tecnología Química, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago 8380000, Chile; (S.A.); (S.P.)
| | - Jorge Saavedra-Torrico
- Escuela de Alimentos, DataChem Analytics, Pontificia Universidad Católica de Valparaíso, Valparaíso 2340025, Chile;
| | - Mauricio Donders
- Panel de Cata Aceite de Oliva Virgen UTEM, Facultad de Ciencias Naturales, Matemática y del Medio Ambiente, Universidad Tecnológica Metropolitana, Santiago 7800002, Chile; (M.D.); (C.B.)
| | - Chris Bustamante
- Panel de Cata Aceite de Oliva Virgen UTEM, Facultad de Ciencias Naturales, Matemática y del Medio Ambiente, Universidad Tecnológica Metropolitana, Santiago 7800002, Chile; (M.D.); (C.B.)
| | - Betsabet Sepúlveda
- Centro Para el Desarrollo de la Química—CEPEDEQ, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago 8380000, Chile;
| | - Francisco Tapia
- Instituto de Investigaciones Agropecuarias (INIA Intihuasi), La Serena 1700000, Chile;
| | | | - Nalda Romero
- Departamento de Ciencia de los Alimentos y Tecnología Química, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago 8380000, Chile; (S.A.); (S.P.)
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3
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Novoselić A, Gallina Tosci T, Klisović D, Tura M, Brkić Bubola K. Compositional Changes during Storage of Industrially Produced Olive Oils Co-Milled with Olive Leaves. Foods 2023; 13:73. [PMID: 38201101 PMCID: PMC10778488 DOI: 10.3390/foods13010073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 12/19/2023] [Accepted: 12/22/2023] [Indexed: 01/12/2024] Open
Abstract
The possibility of enriching the oil produced from Leccino cultivar olive fruits with phenolic and volatile compounds by adding olive leaves (2.5%) during industrial-scale production were investigated. Furthermore, the influence of the addition of leaves on the oil quality, composition, and oxidative stability during storage for 6 and 12 months was studied. A slight negative impact on the oil quality after processing with leaves was determined. The addition of leaves had no influence on the total saturated, monounsaturated, and polyunsaturated fatty acids in oils, while it influenced increases in total phenolic compounds (+29.55%), total secoiridoids (+29.43%), chlorophylls (+47.59%), and the oil stability index (+18.70%), and their higher values were also determined in the stored oils. The addition of leaves increased C5 volatiles (+10.50%) but decreased C6 volatiles (-10.48%). The intensity of most of the positive sensory characteristics increased in fresh oils obtained with leaves, and the established improvements were also maintained in the stored oils. The extractability of olive paste was positively affected by the addition of olive leaves, which increased the oil yield (+27.17%). The obtained results significantly contribute to the knowledge about the possibilities of enriching olive oils with bioactive compounds.
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Affiliation(s)
- Anja Novoselić
- Institute of Agriculture and Tourism, Karla Huguesa 8, 52440 Poreč, Croatia; (A.N.); (K.B.B.)
| | - Tullia Gallina Tosci
- Department of Agricultural and Food Sciences, Alma Mater Studiorum—Università di Bologna, 40126 Bologna, Italy;
| | | | - Matilde Tura
- Department of Agricultural and Food Sciences, Alma Mater Studiorum—Università di Bologna, 40126 Bologna, Italy;
| | - Karolina Brkić Bubola
- Institute of Agriculture and Tourism, Karla Huguesa 8, 52440 Poreč, Croatia; (A.N.); (K.B.B.)
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Taiti C, Masi E, Flamminii F, Di Mattia C, Mancuso S, Marone E. Does the Harvest Type Affect Olive Health? Influence of the Harvesting System and Storage Time on the Chemical, Volatile and Sensory Qualities of Extra Virgin Olive Oils. PLANTS (BASEL, SWITZERLAND) 2023; 12:3843. [PMID: 38005740 PMCID: PMC10674536 DOI: 10.3390/plants12223843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 11/10/2023] [Accepted: 11/12/2023] [Indexed: 11/26/2023]
Abstract
With the aim of investigating the effect of bruising and its development during the postharvest time, olive fruits (Frantoio and Moraiolo), manually and mechanically harvested, were stored in climatic chambers at two different temperatures (5 °C and 18 °C) for five days. Visual observations highlighted changes in the olive peel with discoloration in the damaged areas and tissue bruising. Olive fruit polyphenols, volatile organic compounds (VOCs) and other oil quality parameters (phenolic content, free acidity and peroxide index) and sensory assessment were evaluated. Analyses were carried out on fruits and experimental extra virgin oils at harvesting and after 5 days of fruit storage. The results highlight that low-temperature storage (5 °C for 5 days) may contribute to the maintenance of high olive oil quality, and the quality of olives stored at room temperature drastically decreases after 5 days of storage. Moreover, mechanical harvesting, compared to manual harvesting, does not seem to affect the final oil quality, at least at harvesting, but seems to determine differences in the long-term storage period. Finally, the samples stored at 18 °C showed a quality deterioration with the development of sensorial defects.
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Affiliation(s)
- Cosimo Taiti
- Department of Agri-Food and Environmental Science, University of Florence, Sesto Fiorentino, 50019 Firenze, Italy; (E.M.); (S.M.)
| | - Elisa Masi
- Department of Agri-Food and Environmental Science, University of Florence, Sesto Fiorentino, 50019 Firenze, Italy; (E.M.); (S.M.)
| | - Federica Flamminii
- Department of Innovative Technologies in Medicine and Dentistry, University “G. d’Annunzio” of Chieti-Pescara, Via dei Vestini, 66100 Chieti, Italy;
| | - Carla Di Mattia
- Department of Biosciences and Technologies for Agriculture, Food and Environment, University of Teramo, Via R. Balzarini 1, 64100 Teramo, Italy; (C.D.M.); (E.M.)
| | - Stefano Mancuso
- Department of Agri-Food and Environmental Science, University of Florence, Sesto Fiorentino, 50019 Firenze, Italy; (E.M.); (S.M.)
| | - Elettra Marone
- Department of Biosciences and Technologies for Agriculture, Food and Environment, University of Teramo, Via R. Balzarini 1, 64100 Teramo, Italy; (C.D.M.); (E.M.)
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Boudebouz A, Romero A, Hermoso JF, Boqué R, Mestres M. Effect of Hopper Loading on the Formation of Alkyl Alcohols in Olive Fruits and Its Relationship with Sensory Quality Losses of Virgin Olive Oil. Foods 2023; 12:2633. [PMID: 37444371 DOI: 10.3390/foods12132633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 07/05/2023] [Accepted: 07/06/2023] [Indexed: 07/15/2023] Open
Abstract
The storage of olives in large hoppers is a widespread practice in oil mills, but these large volumes and their unloading can cause a physical deterioration of the olives that will affect the quality of the oil obtained. This research deals with the effect of hopper charge on the formation of alkyl alcohols in olive fruits and its relationship with the sensory quality losses of 'Arbequina' virgin olive oil. The contents of ethanol, methanol, and acetaldehyde were measured in olive samples loaded and stored for a short time in a large hopper and analyzed at three different hopper-discharging times, which are related to three different positions inside the hopper. The corresponding oil from each sampling was obtained by using ABENCOR and was evaluated by a trained tasting panel. Results showed that the ethanol content in olives increased during their storage in the hopper, while methanol and acetaldehyde contents did not show significant differences. Regarding their position in the hopper, fruits located at the bottom or on the lateral sides showed a greater deterioration. The sensory analyses showed an inverse relationship between the positive attributes of olive oils and their content of alcohols.
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Affiliation(s)
- Abdelaziz Boudebouz
- Department of Analytical Chemistry and Organic Chemistry, Universitat Rovira i Virgili (URV)-Chemometrics and Sensorics for Analytical Solutions Group (ChemoSens), Campus Sescelades, 43007 Tarragona, Spain
- Institut de Recerca i Tecnologia Agroalimentària (IRTA-Mas de Bover), Ctra Reus-El Morell Km 3.8, 43120 Constantí, Spain
| | - Agustí Romero
- Institut de Recerca i Tecnologia Agroalimentària (IRTA-Mas de Bover), Ctra Reus-El Morell Km 3.8, 43120 Constantí, Spain
| | - Juan-F Hermoso
- Institut de Recerca i Tecnologia Agroalimentària (IRTA-Mas de Bover), Ctra Reus-El Morell Km 3.8, 43120 Constantí, Spain
| | - Ricard Boqué
- Department of Analytical Chemistry and Organic Chemistry, Universitat Rovira i Virgili (URV)-Chemometrics and Sensorics for Analytical Solutions Group (ChemoSens), Campus Sescelades, 43007 Tarragona, Spain
| | - Montserrat Mestres
- Department of Analytical Chemistry and Organic Chemistry, Universitat Rovira i Virgili (URV)-Chemometrics and Sensorics for Analytical Solutions Group (ChemoSens), Campus Sescelades, 43007 Tarragona, Spain
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6
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Geana EI, Ciucure CT, Apetrei IM, Clodoveo ML, Apetrei C. Discrimination of Olive Oil and Extra-Virgin Olive Oil from Other Vegetable Oils by Targeted and Untargeted HRMS Profiling of Phenolic and Triterpenic Compounds Combined with Chemometrics. Int J Mol Sci 2023; 24:ijms24065292. [PMID: 36982366 PMCID: PMC10049382 DOI: 10.3390/ijms24065292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 02/23/2023] [Accepted: 03/08/2023] [Indexed: 03/12/2023] Open
Abstract
Extra-virgin olive oil (EVOO) and virgin olive oil (VOO) are valuable natural products of great economic interest for their producing countries, and therefore, it is necessary to establish methods capable of proving the authenticity of these oils on the market. This work presents a methodology for the discrimination of olive oil and extra-virgin olive oil from other vegetable oils based on targeted and untargeted high-resolution mass spectrometry (HRMS) profiling of phenolic and triterpenic compounds coupled with multivariate statistical analysis of the data. Some phenolic compounds (cinnamic acid, coumaric acids, apigenin, pinocembrin, hydroxytyrosol and maslinic acid), secoiridoids (elenolic acid, ligstroside and oleocanthal) and lignans (pinoresinol and hydroxy and acetoxy derivatives) could be olive oil biomarkers, whereby these compounds are quantified in higher amounts in EVOO compared to other vegetable oils. The principal component analysis (PCA) performed based on the targeted compounds from the oil samples confirmed that cinnamic acid, coumaric acids, apigenin, pinocembrin, hydroxytyrosol and maslinic acid could be considered as tracers for olive oils authentication. The heat map profiles based on the untargeted HRMS data indicate a clear discrimination of the olive oils from the other vegetable oils. The proposed methodology could be extended to the authentication and classification of EVOOs depending on the variety, geographical origin, or adulteration practices.
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Affiliation(s)
- Elisabeta-Irina Geana
- National Research and Development Institute for Cryogenics and Isotopic Technologies—ICSI, Rm. Valcea, 240050 Râmnicu Vâlcea, Romania
| | - Corina Teodora Ciucure
- National Research and Development Institute for Cryogenics and Isotopic Technologies—ICSI, Rm. Valcea, 240050 Râmnicu Vâlcea, Romania
| | - Irina Mirela Apetrei
- Department of Pharmaceutical Sciences, Medical and Pharmaceutical Research Center, Faculty of Medicine and Pharmacy, “Dunarea de Jos” University of Galati, 800008 Galati, Romania
| | - Maria Lisa Clodoveo
- Interdisciplinary Department of Medicine, University Aldo Moro Bari, 70125 Bari, Italy
| | - Constantin Apetrei
- Department of Chemistry, Physics and Environment, “Dunarea de Jos” University of Galati, 800008 Galati, Romania
- Correspondence: ; Tel.: +40-727-580914
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Impact of Frost on the Morphology and Chemical Composition of cv. Santulhana Olives. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12031222] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Frost events and extreme weather phenomena greatly affect several characteristics of the olive fruit. This study evaluated the impact of frost on the morphology, composition (moisture, fat, fatty acids, tocopherols, and total phenolic contents), and antioxidant activity of olives of cv. Santulhana. A total of 14 trees from the same geographical region (Santulhão, northeast of Portugal) were chosen, including trees subjected or not subjected to frost conditions (n = 7 each). The results showed that frost led to morphological changes in olive fruits, particularly in terms of weight and diameter, which were imposed by a huge decrease in the moisture content (−20%). Fat relative content increased as a consequence of the water loss (+29% in fresh pulp weight), with a slight reduction of the relative abundance of saturated fatty acids (−4%) and tocopherol contents in the fat (−17%). However, the total phenolic contents and antioxidant activity were severely affected (−70% and −42%, respectively), with potential consequences for the olive oil stability and sensorial attributes. Principal component analysis showed that both morphological and chemical parameters could be used as biomarkers to identify olives subjected or not subjected to frost. The overall negative impact of frost on the minor antioxidant contents of cv. Santulhana olives may anticipate a quality loss of olive oils extracted from olives affected by frost.
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Cold Storage and Temperature Management of Olive Fruit: The Impact on Fruit Physiology and Olive Oil Quality—A Review. Processes (Basel) 2021. [DOI: 10.3390/pr9091543] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Cold storage of olive fruit has been the subject of study for over more than 50 years. From the 1990s on, an increasing amount of knowledge is build-up about the impact of the conservation on the physiological response of the fruit as well as on the quality of the extracted oil therefrom. This review offers a comprehensive synopsis of this research, discusses the most important influential factors and summarizes the results on the influence of the studied parameters on both the fruit and the oil. Currently, changing climatic conditions, new harvesting techniques and a more demanding consumer market are triggering the need to broaden this strict focus on conservation. A more dynamic view on the effects of temperature from the moment the fruit is harvested up to the oil extraction process, reveals the necessity to manage this crucial influential factor more diversely. An overview of how this management can take form is structured through a focus on the different phases of the postharvest processing and the widely different harvesting scales. Future prospects of research are presented based on the actual state of the art of cold storage research as well as on the necessities that come forward from a broader fruit temperature management perspective.
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Varzakas T. Extra Virgin Olive Oil (EVOO): Quality, Safety, Authenticity, and Adulteration. Foods 2021; 10:foods10050995. [PMID: 34063199 PMCID: PMC8147458 DOI: 10.3390/foods10050995] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 04/29/2021] [Accepted: 04/30/2021] [Indexed: 01/15/2023] Open
Abstract
The prevention and bioactivity effects associated with the so-called "Mediterranean diet" make olive oil the most consumed edible fat in the food intake of the Mediterranean basin [...].
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Affiliation(s)
- Theodoros Varzakas
- Department Food Science and Technology, University of the Peloponnese, 24100 Kalamata, Greece
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10
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Adjustment of Olive Fruit Temperature before Grinding for Olive Oil Extraction. Experimental Study and Pilot Plant Trials. Processes (Basel) 2021. [DOI: 10.3390/pr9040586] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Harvesting at high temperatures and bulk transport can negatively influence the quality of olives and lead to undesirable alterations in the extracted oil. Cooling the fruit in the field would be the most logical solution, but it means that the olives arrive too cold at the mill for immediate processing. In this work, the use of warm water in the washing tub to warm up the fruit before grinding instead of flash heat treatment on the paste was assessed in two experiments. In the first one, at the laboratory level, the temperature after milling was determined in three olive cultivars, previously stored at 5 or 10 °C, and then submerged at different water temperatures (25, 30, and 35 °C) for 15, 30, 45, and 60 s. In the second one, two batches of olives were cooled in the field at 5 °C and then conditioned with washing water to obtain a paste at the entrance of the pilot plant malaxer at 27 °C. The temperature of the olives was measured at five points from the discharging up to their entering, as paste, into the malaxer. The results demonstrated the feasibility of the method as the temperature of the ground olives was kept at the desired temperature (28 ± 1 °C). The trials highlight the potential for automating an even more precise adjustment of the temperature of the olives before milling once the washing tub is equipped with a safe heating system.
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