Journal of the science of food and agriculture, Jan 5, 2017
Olive oil extraction generates a large amount of residue consisting mainly of the pomace and leav... more Olive oil extraction generates a large amount of residue consisting mainly of the pomace and leaves when using a two-phase centrifugation system. The aim of this study was to assess the content of phenolic and triterpene compounds in the by-products produced in Spanish olive oil mills. Olive pomace had concentrations of phenolic and triterpene substances lower than 2 and 3 g kg(-1) , respectively. The leaves contained a high concentration of these substances, although those collected from ground-picked olives had lost most of their phenolic compounds. Moreover, the sediment from the bottom of the olive oil storage tanks did not have a significant amount of these substances. By contrast, a new by-product called olive pomace skin has been revealed as a very rich source of triterpenic acids, the content of which can reach up to 120 g kg(-1) in this waste product, maslinic acid comprising around 70% of total triterpenics. Among the by-products generated during extraction of olive oil, o...
The bitter taste of olives is mainly caused by the phenolic compound named oleuropein and the mec... more The bitter taste of olives is mainly caused by the phenolic compound named oleuropein and the mechanism of its hydrolysis during the processing of natural green olives was studied. First, a rapid chemical hydrolysis of oleuropein takes place at a high temperature of 40°C and at a low pH value of 2.8, but the chemical hydrolysis of the bitter compound is slow at the common range of pH for these olives (3.8-4.2). However, decarboxymethyl elenolic acid linked to hydroxytyrosol and hydroxytyrosol have been found in a high concentration during the elaboration of natural green olives. When olives were heated at 90°C for 10min before brining, these compounds are not formed. Hence, the debittering process in natural green olives is due to the activity of β-glucosidase and esterase during the first months of storage and then a slow chemical hydrolysis of oleuropein happens throughout storage time.
Olives and Olive Oil in Health and Disease Prevention, 2010
Publisher Summary At present, both olive oil and table olives are important components of the Med... more Publisher Summary At present, both olive oil and table olives are important components of the Mediterranean diet and are largely consumed throughout the world. In addition, there are many enterprises that commercialize olive leaf extracts to treat a myriad of diseases, many of them caused by microorganisms. This chapter presents features of the main food-related bacteria pathogens investigated in relation to olive antimicrobials. It has been demonstrated that the main phenolic compound in olive brines is hydroxytyrosol, a component of the oleuropein moiety, which inhibited the growth of Lactobacillus plantarum in a model system, but its presence in the brines of both olives non-treated and treated with NaOH did not lead to an explanation for the lack of lactic acid fermentation in the former olive brines. The bactericidal action of virgin olive oil is higher than that of other foodstuffs such as wine, tea, coffee, beer and others. Olive oil could be a hurdle component in certain processed foods and exert a protective effect against foodborne pathogens when contaminated foods are ingested. The antimicrobial compounds of olive oil possess a strong anti- H. pylori activity that could be useful for the prevention of peptic ulcers and cancers in the future.
The aim of this work was to assess the in vitro antimicrobial effects that wastewaters from alpeo... more The aim of this work was to assess the in vitro antimicrobial effects that wastewaters from alpeorujo oil extraction have against phytopathogenic bacteria and fungi. Alpeorujo was stored for 6 months and then processed to extract its oil, pomace, and a new liquid waste (OWSA), which was characterized by its content in phenolic compounds. OWSA at 20% decreased bu >4 log the population of Erwinia spp., Pseudomonas spp., and Clavibacter spp. viable cells in test tubes, whereas OWSA at 50% in agar medium was necessary to inhibit mycelial growth of most fungi. It was found that the bactericidal effect was due to the joint action of low molecular mass phenolic compounds, although neither hydroxytyrosol, its glucosides, hydroxytyrosol glycol, nor a glutaraldehyde-like compound individually explained this bioactivity. Hence, OWSA constitutes a promising natural solution to fight plant phytopathogenic bacteria and fungi.
In this study, green olives preserved in acidified brine were debittered by subjecting them to an... more In this study, green olives preserved in acidified brine were debittered by subjecting them to an overpressure of oxygen or air for 1-3 days. It was demonstrated that fruits lost their bitter taste due to the enzymatic oxidation of the phenolic compounds, in particular, the glucoside oleuropein. Hence, the concentrations of both o-diphenols and, to a lesser extent, monophenols decreased in the olives with oxidation. This process also gave rise to a darkening effect on the superficial and interior color of the olives, which turned from yellow-brown to brown. Likewise, the effect of several variables on the oxidation rate of the olives, such as type of gas (oxygen, air), temperature, overpressure level, and size of the olives, was also studied. Results indicate that a new debittering method which could be a promising alternative to the treatment of fruits with NaOH is available to the industry. In addition, a new product with different color and texture from the traditional table olives is presented.
Frequently, a delay or lack of lactic acid fermentation occurs during the processing of Spanish-s... more Frequently, a delay or lack of lactic acid fermentation occurs during the processing of Spanish-style green olives, in particular of the Manzanilla variety. Many variables can affect the progress of fermentation such as temperature, nutrients, salt concentration, antimicrobials in brines, and others. In this study, it was demonstrated that an inappropriate alkaline treatment (low NaOH strength and insufficient alkali penetration) allowed for the presence of several antimicrobial compounds in brines, which inhibited the growth of Lactobacillus pentosus. These substances were the dialdehydic form of decarboxymethyl elenolic acid either free or linked to hydroxytyrosol and an isomer of oleoside 11-methyl ester. Olive brines, from olives treated with a NaOH solution of low concentration up to 1/2 the distance to the pit, contained these antimicrobials, and no lactic acid fermentation took place in them. By contrast, a more intense alkaline treatment (2/3 lye depth penetration) gave rise to an abundant growth of lactic acid bacteria without any antimicrobial in brines. Therefore, the precise cause of stuck fermentation in Manzanilla olive brines was demonstrated for the first time and this finding will contribute to better understand the table olive fermentation process.
An experimental investigation was carried out for the first time on the triterpenic acids in tabl... more An experimental investigation was carried out for the first time on the triterpenic acids in table olives. Maslinic acid was found in a higher concentration than oleanolic acid in the flesh of 17, unprocessed olive varieties, with the Picual and the Manzanilla varieties showing the ...
Journal of the science of food and agriculture, Jan 5, 2017
Olive oil extraction generates a large amount of residue consisting mainly of the pomace and leav... more Olive oil extraction generates a large amount of residue consisting mainly of the pomace and leaves when using a two-phase centrifugation system. The aim of this study was to assess the content of phenolic and triterpene compounds in the by-products produced in Spanish olive oil mills. Olive pomace had concentrations of phenolic and triterpene substances lower than 2 and 3 g kg(-1) , respectively. The leaves contained a high concentration of these substances, although those collected from ground-picked olives had lost most of their phenolic compounds. Moreover, the sediment from the bottom of the olive oil storage tanks did not have a significant amount of these substances. By contrast, a new by-product called olive pomace skin has been revealed as a very rich source of triterpenic acids, the content of which can reach up to 120 g kg(-1) in this waste product, maslinic acid comprising around 70% of total triterpenics. Among the by-products generated during extraction of olive oil, o...
The bitter taste of olives is mainly caused by the phenolic compound named oleuropein and the mec... more The bitter taste of olives is mainly caused by the phenolic compound named oleuropein and the mechanism of its hydrolysis during the processing of natural green olives was studied. First, a rapid chemical hydrolysis of oleuropein takes place at a high temperature of 40°C and at a low pH value of 2.8, but the chemical hydrolysis of the bitter compound is slow at the common range of pH for these olives (3.8-4.2). However, decarboxymethyl elenolic acid linked to hydroxytyrosol and hydroxytyrosol have been found in a high concentration during the elaboration of natural green olives. When olives were heated at 90°C for 10min before brining, these compounds are not formed. Hence, the debittering process in natural green olives is due to the activity of β-glucosidase and esterase during the first months of storage and then a slow chemical hydrolysis of oleuropein happens throughout storage time.
Olives and Olive Oil in Health and Disease Prevention, 2010
Publisher Summary At present, both olive oil and table olives are important components of the Med... more Publisher Summary At present, both olive oil and table olives are important components of the Mediterranean diet and are largely consumed throughout the world. In addition, there are many enterprises that commercialize olive leaf extracts to treat a myriad of diseases, many of them caused by microorganisms. This chapter presents features of the main food-related bacteria pathogens investigated in relation to olive antimicrobials. It has been demonstrated that the main phenolic compound in olive brines is hydroxytyrosol, a component of the oleuropein moiety, which inhibited the growth of Lactobacillus plantarum in a model system, but its presence in the brines of both olives non-treated and treated with NaOH did not lead to an explanation for the lack of lactic acid fermentation in the former olive brines. The bactericidal action of virgin olive oil is higher than that of other foodstuffs such as wine, tea, coffee, beer and others. Olive oil could be a hurdle component in certain processed foods and exert a protective effect against foodborne pathogens when contaminated foods are ingested. The antimicrobial compounds of olive oil possess a strong anti- H. pylori activity that could be useful for the prevention of peptic ulcers and cancers in the future.
The aim of this work was to assess the in vitro antimicrobial effects that wastewaters from alpeo... more The aim of this work was to assess the in vitro antimicrobial effects that wastewaters from alpeorujo oil extraction have against phytopathogenic bacteria and fungi. Alpeorujo was stored for 6 months and then processed to extract its oil, pomace, and a new liquid waste (OWSA), which was characterized by its content in phenolic compounds. OWSA at 20% decreased bu >4 log the population of Erwinia spp., Pseudomonas spp., and Clavibacter spp. viable cells in test tubes, whereas OWSA at 50% in agar medium was necessary to inhibit mycelial growth of most fungi. It was found that the bactericidal effect was due to the joint action of low molecular mass phenolic compounds, although neither hydroxytyrosol, its glucosides, hydroxytyrosol glycol, nor a glutaraldehyde-like compound individually explained this bioactivity. Hence, OWSA constitutes a promising natural solution to fight plant phytopathogenic bacteria and fungi.
In this study, green olives preserved in acidified brine were debittered by subjecting them to an... more In this study, green olives preserved in acidified brine were debittered by subjecting them to an overpressure of oxygen or air for 1-3 days. It was demonstrated that fruits lost their bitter taste due to the enzymatic oxidation of the phenolic compounds, in particular, the glucoside oleuropein. Hence, the concentrations of both o-diphenols and, to a lesser extent, monophenols decreased in the olives with oxidation. This process also gave rise to a darkening effect on the superficial and interior color of the olives, which turned from yellow-brown to brown. Likewise, the effect of several variables on the oxidation rate of the olives, such as type of gas (oxygen, air), temperature, overpressure level, and size of the olives, was also studied. Results indicate that a new debittering method which could be a promising alternative to the treatment of fruits with NaOH is available to the industry. In addition, a new product with different color and texture from the traditional table olives is presented.
Frequently, a delay or lack of lactic acid fermentation occurs during the processing of Spanish-s... more Frequently, a delay or lack of lactic acid fermentation occurs during the processing of Spanish-style green olives, in particular of the Manzanilla variety. Many variables can affect the progress of fermentation such as temperature, nutrients, salt concentration, antimicrobials in brines, and others. In this study, it was demonstrated that an inappropriate alkaline treatment (low NaOH strength and insufficient alkali penetration) allowed for the presence of several antimicrobial compounds in brines, which inhibited the growth of Lactobacillus pentosus. These substances were the dialdehydic form of decarboxymethyl elenolic acid either free or linked to hydroxytyrosol and an isomer of oleoside 11-methyl ester. Olive brines, from olives treated with a NaOH solution of low concentration up to 1/2 the distance to the pit, contained these antimicrobials, and no lactic acid fermentation took place in them. By contrast, a more intense alkaline treatment (2/3 lye depth penetration) gave rise to an abundant growth of lactic acid bacteria without any antimicrobial in brines. Therefore, the precise cause of stuck fermentation in Manzanilla olive brines was demonstrated for the first time and this finding will contribute to better understand the table olive fermentation process.
An experimental investigation was carried out for the first time on the triterpenic acids in tabl... more An experimental investigation was carried out for the first time on the triterpenic acids in table olives. Maslinic acid was found in a higher concentration than oleanolic acid in the flesh of 17, unprocessed olive varieties, with the Picual and the Manzanilla varieties showing the ...
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