Aroma profile and volatile composition of black ripe olives (Manzanilla and Hojiblanca cultivars)

The aroma profile and volatile composition of 8 samples of black ripe olives from Manzanilla and Hojiblanca cultivars were analyzed with the aim to characterize this type of table olive. The aroma of samples was described by a sensory panel using quantitative descriptive analysis (QDA), whereas the volatiles were analyzed by headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS). Eleven odor descriptors (briny, sautéed mushroom, earthy/soil-like, oak barrel, nutty, artificial fruity/floral, natural fruity/floral, vinegary, alcohol, fishy/ocean-like, and cheesy) were evaluated, of which only one descriptor (briny) showed a significant difference between cultivars. A total of 74 volatile compounds were identified in the headspace of samples, of which 12 were identified as significant volatiles contributing to the discrimination between Manzanilla and Hojiblanca black ripe olives. Partial least squares (PLS) regression was able to predict one odor descriptor (nutty) with sufficient accuracy and allowed identifying the volatiles that highly contributed to three odor descriptors of black ripe olives (nutty, natural fruity/floral, and cheesy).

Processing of table olives with KOH and characterization of the wastewaters as potential fertilizer

In Mediterranean countries the table olive industry produces a huge volume of wastewaters that are phytotoxic due to their high sodium content. Olives intended for Spanish-style green olives are currently debittered with NaOH that generates lyes and washing waters that cannot be used for agronomic purposes. In this study, the substitution of NaOH with KOH during the debittering of Manzanilla and Hojiblanca cultivars was assessed as well as the vacuum evaporation of the olive wastewaters to comply with fertilizer requirements. Typical lactic acid fermentation occurred in brines of olives treated with KOH and a final product with similar color and flavor characteristics to those treated with NaOH was achieved. However, lower texture was found in olives debittered with KOH than those with NaOH, using them at the same molar concentration. Furthermore, the lyes and washing waters from the KOH treatment were concentrated up to 10% of their initial volume and they complied with Spanish requirements to be considered as organo-mineral fertilizers (C_organic > 4%, K₂O > 2%, N_total + K₂0 > 6%) although an external source of nitrogen would be needed. They also had a high content in phenolic compounds, particularly hydroxytyrosol. This research demonstrates that table olives can be processed with KOH and the generated waste streams could have potential applications in agriculture or being a source of bioactive substances.

Changes in volatile composition during the processing and storage of black ripe olives

The present study revealed the effects of each step of black ripe olive processing (preservation, darkening, packing + sterilization) and storage on the volatile composition of two olive cultivars (Manzanilla and Hojiblanca). The preservation step enriched the volatile profile of the olives, mainly in ethyl acetate, methyl acetate, and ethanol. The darkening step produced the total or partial elimination of 55-65% of the volatiles identified before this step. Around 70% of the volatiles in the final products corresponded to compounds that were formed or increased significantly as a result of the sterilization treatment at 121 °C. Although differences in the volatile compositions and contents between Manzanilla and Hojiblanca were found, the dominant volatiles in both cultivars were benzaldehyde, dimethyl sulfide and ethyl acetate. Storage for 8 months had little influence on their volatile profiles, although the stability of individual volatiles in Manzanilla was better than that in the Hojiblanca cultivar.

Stability of color in Spanish-style green table olives pasteurized and stored in plastic containers

BACKGROUND

There is an increasing interest in the use of pasteurizable plastic packaging by the olive industry. In order to investigate the change from traditional glass or varnished can containers to plastic packaging, the proper plastic material that is compatible with fermented olives while maintaining color quality during pasteurization treatment and storage must be selected. This work is focused on color stability in two distinct pasteurizable plastic containers with different oxygen permeability.

RESULTS

In PET + MDPE/EVOH (polyethylene terephthalate + medium-density polyethylene/ethylene vinyl alcohol) pouches, pasteurization provoked severe browning which drastically decreased their color shelf life (<6 weeks). However, this browning did not occur in the unpasteurized product without preservatives owing to the presence of microorganisms. In AlOx-coated PET + MDPE (aluminum oxide coating on polyethylene terephthalate + medium-density polyethylene) pouches, color changes were small or negligible throughout storage, especially if ascorbic acid was added to the packing solution (shelf life > 6.5 months).

CONCLUSION

The plastic material had a significant effect on the retention of color of the pasteurized product. The use of AlOx-coated PET + MDPE pouches could be an alternative to traditional packaging for the pasteurization and storage of Spanish-style green olives from a color quality standpoint. © 2017 Society of Chemical Industry.

Assays to control the development of the green staining alteration in Spanish-style green olives of the Gordal variety

BACKGROUND

Olives of the Gordal variety processed according to the Spanish style sometimes develop an alteration in color known as green staining (GS), due to the formation of harmless copper-chlorophyll complexes, which makes the product less valuable. The aim of this study was to investigate methods to minimize the impact that this alteration has for the table olive industry.

RESULTS

Calcium chloride, sorbic, benzoic and ascorbic acids and SO2 did not inhibit the development of the alteration in olives packed under their own fermentation brine or new fresh brine. It was also discovered that the incubation of olive samples at 45 °C for 20 days accelerates the formation of GS and can be a very useful tool to predict the incidence of the alteration in advance. By applying this test to numerous industrial tanks for four consecutive seasons, it was found that GS was mainly present in olives harvested at the beginning of the season.

CONCLUSION

The formation of GS in olives of the Gordal variety is time- and temperature-dependent, and none of the additives tested avoided or retarded the development of the alteration. However, an accelerated test to predict the development of GS formation has been proposed that could contribute to minimize the effects of the alteration. © 2015 Society of Chemical Industry.

Production of 4-ethylphenol in alperujo by Lactobacillus pentosus

BACKGROUND

Alperujo is the paste generated from the two-phase extraction system of olive oil. This wet pomace must be stored for several months and, during this period, the formation of 4-ethyphenol provokes a strong off-odour. The aim of this work was to identify the microorganisms able to produce this volatile phenol.

RESULTS

Yeast and bacterial strains were isolated from stored alperujo and tested for their ability to metabolize p-coumaric acid and form 4-ethylphenol. Among them, Lactobacillus pentosus was the microorganism that both in synthetic medium and alperujo gave rise to 4-ethylphenol formation. This microorganism did not grow in alperujo acidified to pH 2, thereby confirming that acidification as the best method to control odour emissions during alperujo storage.

CONCLUSION

Lactic acid bacteria, particularly Lactobacillus pentosus, can be responsible for the formation of the off-odour caused by 4-ethylphenol during the storage of alperujo. This odour can be prevented by acidifying the alperujo.

Stability of monosodium glutamate in green table olives and pickled cucumbers as a function of packing conditions and storage time

The effects of different packing conditions and storage times on the stability of monosodium glutamate (MSG) added to two different fermented vegetables (Spanish-type green table olives and pickled cucumbers) were studied. Factors such as packaging material (glass bottle versus plastic pouch), heat treatment (pasteurisation versus non-pasteurisation), and the presence or not of a preservative compound (potassium sorbate) were considered. The MSG content of pickled cucumbers was stable for up to 1 year of storage in all packing conditions studied. The MSG content also remained stable in pasteurised green table olives. On the contrary, MSG was extensively degraded (>75% degradation) after 54 weeks of storage in unpasteurised green olives with a higher degradation rate in glass bottles compared with plastic pouches. In the presence of potassium sorbate, MSG was also considerably degraded in olives packed in plastic pouches (>50% degradation), but hardly degraded in glass bottles. The results indicate that MSG degradation in olives is due to the action of both lactic acid bacteria and yeasts, with the formation of γ-aminobutyric acid as the major end-product.

Assessment of Helicobacter pylori eradication by virgin olive oil

BACKGROUND

 A recent study conducted by Medina et al. disclosed that virgin olive oil has a bactericidal effect in vitro against Helicobacter pylori because of its contents of certain phenolic compounds with dialdehydic structures. We carried out two clinical trials to evaluate the effect of virgin olive oil on H. pylori-infected individuals.

MATERIALS AND METHODS

 Two different pilot studies were performed with 60 H. pylori-infected adults. In the first study, thirty subjects who tested positive for H. pylori received 30 g of washed virgin olive oil for 14 days, and after 1 month, the patients took 30 g of unwashed virgin olive oil for another 14 days. In a second study, a group of 30 subjects received 30 g of a different virgin olive oil for 14 days. Helicobacter pylori-infection status was checked by the urea breath test.

RESULTS

 Helicobacter pylori was eradicated in 8 of 30 individuals when microorganism status was checked after 4-6 weeks from the first clinical intervention although 12 of 30 individuals did not show H. pylori infection at 24-72 hour of the last oil dose. Eradication rates were 27 and 40% by intention to treat and per protocol, respectively. Moreover, only 3 of 30 individuals were H. pylori negative after 4-6 weeks from the second clinical intervention but 5 of 30 were negative at 24-72 hour of the last oil dose. Eradication rates were 10 and 11% by intention to treat and per protocol, respectively. It must also be noted that 13 subjects withdrew from the studies because of taste and nausea drawbacks.

CONCLUSIONS

 The administration of virgin olive oil showed moderate effectiveness in eradicating H. pylori. Further studies are needed to confirm these findings, especially with longer periods, different administration conditions, and several types of olive oils.

Effect of processing and storage time on the contents of organosulfur compounds in pickled blanched garlic

The influence of processing, with and without fermentation, on the contents of organosulfur compounds, namely, γ-glutamyl peptides, S-alk(en)yl-L-cysteine sulfoxides (ACSOs), and S-allyl-L-cysteine (SAC), in pickled blanched garlic was evaluated. For each processing type, the effect of the preservation method and storage time was also analyzed. Blanching in hot water (90 °C for 5 min) hardly affected the individual organosulfur compound content. The fermentation and packing steps negatively affected the levels of all compounds except for SAC. The content of this compound increased during storage at room temperature whereas γ-glutamyl peptides and ACSOs were degraded to various extents. The pasteurization treatment itself had no significant effect on the concentrations of organosulfur compounds. Use of the corresponding fermentation brine in the case of the fermented product in conjunction with refrigerated storage was found to be the best method to preserve the levels of organosulfur compounds in pickled garlic stored for up to one year.

Antimicrobial activity of olive solutions from stored Alpeorujo against plant pathogenic microorganisms

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.

Bactericidal activity of glutaraldehyde-like compounds from olive products

The bactericidal effects of several olive compounds (nonenal, oleuropein, tyrosol, the dialdehydic form of decarboxymethyl elenolic acid either free [EDA] or linked to tyrosol [TyEDA] or to hydroxytyrosol [HyEDA]), other food phenolic compounds (catechin, epicatechin, eugenol, thymol, carvacrol, and carnosic acid), and commercial disinfectants (glutaraldehyde [GTA] and ortho-phthalaldehyde [OPA]), were tested against strains of Pseudomonas fluorescens, Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli. It was found that the bactericidal activities of olive GTA-like compounds (EDA, HyEDA, and TyEDA) were greater than those exerted by several food phenolic substances. Surprisingly, these olive antimicrobials were as active as the synthetic biocides GTA and OPA against the four bacteria studied. Thus, it has been proposed that the bactericidal activity of the main olive antimicrobials is primarily due to their dialdehydic structure, which is similar to that of the commercial biocides GTA and OPA. Our results clearly reveal that olive GTA-like compounds possess a strong bactericidal activity even greater than that of other food phenolic compounds or synthetic biocides.

Debittering of olives by polyphenol oxidation

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.

Main antimicrobial compounds in table olives

The inhibitors involved in the lactic acid fermentation of table olives were investigated in aseptic olive brines of the Manzanilla and Gordal varieties. Phenolic and oleosidic compounds in these brines were identified by high-performance liquid chromatography with ultraviolet and electrospray ionization mass spectrometry detection, and several substances were also characterized by nuclear magnetic resonance. Among these compounds, the dialdehydic form of decarboxymethyl elenolic acid linked to hydroxytyrosol showed the strongest antilactic acid bacteria activity, and its presence in brines could explain the growth inhibition of these microorganisms during olive fermentation. However, it was found that the dialdehydic form of decarboxymethyl elenolic acid, identified for the first time in table olives, and an isomer of oleoside 11-methyl ester were also effective against Lactobacillus pentosus and can, therefore, contribute to the antimicrobial activity of olive brines. It must also be stressed that the three new inhibitors discovered in table olive brines exerted a more potent antibacterial activity than the well-studied oleuropein and hydroxytyrosol.

Comparison of the concentrations of phenolic compounds in olive oils and other plant oils: correlation with antimicrobial activity

The antimicrobial activity of different edible vegetable oils was studied. In vitro results revealed that the oils from olive fruits had a strong bactericidal action against a broad spectrum of microorganisms, this effect being higher in general against Gram-positive than Gram-negative bacteria. Thus, olive oils showed bactericidal activity not only against harmful bacteria of the intestinal microbiota (Clostridium perfringens and Escherichia coli) also against beneficial microorganisms such as Lactobacillus acidophilus and Bifidobacterium bifidum. Otherwise, most of the foodborne pathogens tested (Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica, Yersinia sp., and Shigella sonnei) did not survive after 1 h of contact with olive oils. The dialdehydic form of decarboxymethyl oleuropein and ligstroside aglycons, hydroxytyrosol and tyrosol, were the phenolic compounds that statistically correlated with bacterial survival. These findings were confirmed by testing each individual phenolic compound, isolated by HPLC, against L. monocytogenes. In particular, the dialdehydic form of decarboxymethyl ligstroside aglycon showed a potent antimicrobial activity. These results indicate that not all oils classified as "olive oil" had similar bactericidal effects and that this bioactivity depended on their content of certain phenolic compounds.

Vitamin content and amino acid composition of pickled garlic processed with and without fermentation

The effect of processing, with and without fermentation, upon the nutritional composition of pickled garlic was evaluated. On a dry basis, the fermented product had a higher content of riboflavin, alpha-tocopherol, and most individual amino acids but a lower thiamin level than the unfermented product. Ascorbic acid was totally lost during processing. The chemical scores for the unfermented and fermented product were 88 and 108%, respectively, with the limiting amino acid being leucine. Water blanching (90 degrees C for 4 min) affected only the ascorbic acid content, whereas fermentation significantly affected the contents of thiamin, ascorbic acid, and alpha-tocopherol, as well as glutamic acid and arginine. For each processing type, the effect of the preservation method and storage time on vitamins and amino acid composition was also analyzed. In the case of the fermented product, usage of the corresponding fermentation brine plus refrigerated storage was also assayed as the packing/preservation method and was found to give the best result from a nutritional standpoint.

4-Hydroxycyclohexanecarboxylic Acid as a Substrate for Cyclohexanecarboxylic Acid Production during the " Zapatera " Spoilage of Spanish-Style Green Table Olives

Zapatera spoilage was reproduced in Spanish-style green olive brines adjusted to pH 5 and with a concentration of 5% (wt/vol) NaCl. A relationship between the formation of the compound responsible for the zapatera off odor, cyclohexanecarboxylic acid, and consumption of a new compound isolated from olive brines, 4-hydroxycyclohexanecarboxylic acid, was established. When the latter compound was added to a synthetic medium inoculated with a concentrated microbial suspension from a zapatera brine, cyclohexanecarboxylic acid was formed. 4-Hydroxy-cyclohexanecarboxylic acid was not detected in fresh olives, NaOH solutions, or water washes. In normal fermentation brines it was not detected after 30 days of brining, its concentration increasing in a progressive manner thereafter during typical lactic acid fermentation of Spanish-style green olives.

Interstitial emphysema associated with epidural anesthesia for extracorporeal shock-wave lithotripsy

Interstitial emphysema was noted on abdominal radiographs in 38 (15%) of the first 150 patients treated by extracorporeal shock-wave lithotripsy at our hospital. All 38 patients had undergone successful or attempted epidural anesthesia for the lithotripsy. This finding was not seen in any patient who had not undergone epidural puncture. The emphysema is the result of the introduction of air into the paraspinal and back muscles or subcutaneous tissues during attempted or actual puncture of the epidural space. This air was apparent on abdominal radiographs taken after lumbar puncture in 38 (23%) of 167 patients who underwent attempted or actual puncture of the epidural space. The emphysema decreases over the ensuing days, is of no clinical significance, and bears no direct relationship to extracorporeal shock-wave lithotripsy. This finding should not be mistaken for emphysema caused by gas-producing or gas-containing retroperitoneal diseases.