Luis Rejano

Utilization at high pH of starter cultures of lactobacilli for Spanish-style green olive fermentation.

Inoculation at alkaline pH (above 9) of lye-treated green olives with starter cultures of Lactobacillus pentosus CECT 5138 was studied. Despite an initial loss of viability in the order of 1-2 log cycles on average, depending mainly on time of application, cultures grew and initiated an accelerated fermentation process. Inoculation reduced the population of Enterobacteriaceae, and thereby potential spoilage, and produced a quicker acidification of brines and decrease of pH, when compared with control uninoculated batches. Results obtained throughout three consecutive seasons demonstrated that utilization at high pH of starter cultures of lactobacilli is feasible, provided that the inoculum size takes into account the initial low survival.

Chemical profile of industrially fermented green olives of different varieties

Over 160 fermented brines, from green olives of Manzanilla, Hojiblanca, and Gordal varieties processed in five companies in two consecutive seasons, were analysed for physicochemical characteristics, organic acids, sugars, and volatile components. The composition of the brine following fermentation was assumed to be identical to that of the aqueous phase of the olives. Olive variety and processor were found to have a greater influence than season on both physicochemical characteristics and chemical composition. Hojiblanca olives presented values of pH, combined acidity, and volatile acidity significantly (P<0.05) higher than those of Manzanilla and Gordal, reflecting different processing conditions. The volatile/total acidity ratio, which did not differ between varieties or seasons, appeared to correlate with development of the “fourth stage” of fermentation. The major compounds were lactic, acetic, succinic and formic acids, ethanol, and methanol, with the contents of ethanol and formic acid being significantly different in all three varieties. Residual fermentation substrates, such as mannitol, glucose, sucrose, and citric acid, in addition to propanol, propionic acid, 2-butanol, and acetaldehyde, were found in low concentrations.

Lactic acid fermentation and storage of blanched garlic

The controlled fermentation of peeled, blanched garlic, using a starter culture of Lactobacillus plantarum, was studied and compared with that of unblanched garlic. Blanching was carried out in hot water (90 degrees C) for 15 min. The starter grew abundantly in the case of blanched garlic, producing mainly lactic acid and reaching a pH of 3.8 after 7 days, but its growth was inhibited in unblanched garlic. Ethanol and fructose, coming from enzymatic activities of the garlic, and a green pigment were formed during the fermentation of unblanched garlic, but not of blanched garlic. The blanched garlic fermented by L. plantarum, even without a preservation treatment (pasteurization), was microbiologically stable during storage at 30 degrees C in an acidified brine (approximately 3% (w/w) NaCl and pH 3.5 at equilibrium), but fructans were hydrolyzed. The packed fermented product and that obtained by direct packing without fermentation were not significantly different with regard to flavour.

Analysis of zapatera olives by gas and high-performance liquid chromatography

Abstract Gas chromatography and high-performance liquid chromatography were applied to normal and “zapatera” olive brines obtained from typical fermentation brines of green table olives after different treatments. The zapatera samples were obtained by pH adjustment to 5.1 followed by inoculation with a suspension of sediment from a zapatera brine and incubation at 30°C for 40 days. The compounds determined were lactic acid, C 2 -C 6 fatty acids, acetaldehyde, methanol, ethanol, 2-butanol and n -propanol. Normal and zapatera brines were compared to identify components that indicated spoilage. One of these components was found in the gas chromatogram of the volatile fatty acids from the zapatera samples and identified as cyclohexanecarboxylic acid by gas chromatography-mass spectrometry. A comparison of the corresponding aromagrams revealed quantitative differences in aroma composition. Various relationships calculated from the peak areas of selected unknown components in these aromagrams were so distinct as to provide a basis for characterizing zapatera spoilage.

Table Olives: Varieties and Variations

Publisher Summary Table olives are the products prepared from sound fruits of the cultivated olive tree. Table olive production was initially restricted to the producing regions, mainly around the Mediterranean Sea. Today, however, olive preparation has extended to both North and South America, and even Australia. A characteristic common to almost all olive varieties is their extreme bitterness when tasted fresh. The glucoside oleuropein is responsible for this, and the different processing methods are aimed at removing this compound in order to obtain fruits with more-palatable attributes. It could be said that there are as many processing methods as places where olives are consumed. In an attempt to normalize the different products, the International Olive Council has a Trade Standard Applying to Table Olives, in which the types, trade preparations, quality factors, and other properties are described. This chapter aims to describe in detail the different kinds or classifications applicable to table olives, explaining the distinctive traits for each case.

Determination of benzoic and sorbic acids in packaged vegetable products. Comparative evaluation of methods

Three analytical methods for determining sorbic and benzoic acids in various packaged vegetable products were evaluated, with special attention being paid to green olives. Two of these methods used a simple, isocratic, reversed-phase HPLC technique for separating and detecting the preservatives, but differed in the preparation of the sample (extraction with 60% methanol or steam distillation). The third method was based on separation by steam distillation and determination of the acids in the distillate by spectrophotometry. For the olives, while this method proved to be excellent (total error < 25%) for high concentrations (> 100 ppm), the HPLC methods were more efficient for the whole range of concentrations studied (5-500 ppm). Both HPLC methods had detection limits of approximately 1 ppm for the two preservatives. With other sample matrices (tomatoes, cucumbers, caperberries, silver-skinned onions and hot peppers), the three methods proved to be excellent for high concentrations of preservatives (500 ppm), but at low levels (20 ppm), the spectrophotometric method and the HPLC method with extraction by 60% methanol proved to be unacceptable (total error > 50%) in some cases.

Chemical Composition of Fermented Green Olives: Acidity, Salt, Moisture, Fat, Protein, Ash, Fiber, Sugar, and Polyphenol

Publisher Summary Of fermented green olives, alkali-treated green olives in brine, also known as “Spanish-style green olives” or “pickled green olives,” are the most widely distributed and investigated type of table olive. However, there are other traditional preparations of fermented green olives which are of lesser economic importance in the international market, but highly appreciated by consumers in the Mediterranean region. One of these involves the direct brining of green olives without prior de-bittering with NaOH solution. This preparation is known as “untreated green olives in brine,” “naturally green olives,” “directly brined olives,” or “Sicilian-style green olives.” The taste of untreated green olives is completely different from that of alkali-treated fruits, mainly due to the residual bitterness they retain even after a long period of storage in brine. This olive type (green or turning-color) is one of the bases for many other commercial products, such as “seasoned” olives, which are very popular in Spain. When this preparation is made with natural black olives, it is known as Greek-style table olives, and has been extensively studied. This chapter reviews the two processing types of fermented green olive—that is, Spanish-style and untreated (green or turning-color) olives—with special emphasis on the characteristics (physicochemical parameters, chemical composition) of the final product. It presents a summary of information in the literature regarding the major components in the fresh fruit (raw material).

Processing and storage of lye-treated carrots fermented by a mixed starter culture

A mixed culture of Lactobacillus plantarum and Saccharomyces cerevisiae was compared with a single culture of L. plantarum as starter for the fermentation of lye-treated carrots. Using the mixed culture, more than 95% of glucose, fructose and malic acid was consumed after 7 days of fermentation in a brine containing 2.5% w/v NaCl and 0.7% acetic acid, but only 54% of sucrose was degraded. The fermentation products quantified were lactic acid, ethanol and acetic acid and carbon recovery was 88%. Using the single culture of L. plantarum, substrate consumption was lower, and carbon recovery almost 100%. In uninoculated lye-treated carrots, heterofermentative bacteria grew, with the production of considerable amounts of mannitol. In all cases, the stability, sensorial characteristics and carotenoid content of the packed product were studied during 9 months of storage at 30 degrees C, and two different preservation systems were compared: addition of preservatives, approximately 500 and 1000 mg/kg of sorbic and benzoic acid, respectively, and pasteurization at 80 degrees C for 10 min. The pasteurized samples were microbiologically stable during the storage period, while lactic acid bacteria grew in the samples with preservatives. Storage time significantly (P < 0.05) affected the texture and colour parameters (L*, a*, b*) of the carrots, but not the amounts of alpha- and beta-carotene. The type of fermentation had no significant effect on texture, colour parameters or carotenoid content. The preservation method had no significant effect on texture or carotenoid content, but did affect colour (parameter a*). The flavour of carrots fermented by the mixed culture was significantly (P < 0.05) preferred to that of those fermented with a single culture of L. plantarum.

Fermented vegetables containing benzoic and ascorbic acids as additives: benzene formation during storage and impact of additives on quality parameters.

Chemical and sensorial changes related to the use of benzoates and ascorbic acid as additives in packed fermented vegetables were investigated. For this, three selected vegetables (green olives, cucumbers, and caperberries) stored under different conditions (glass or plastic containers, ambient or refrigerated storage) were used. In all cases, benzoic acid remained unchanged (glass bottle) or decreased slightly (plastic pouch) at prolonged storage. Ascorbic acid was partially or totally degraded during storage, the degradation rate depending on the storage conditions and the vegetable matrix. Benzene levels higher than 10 μg/L were found in cucumbers and caperberries containing both additives, but only when packed in plastic pouches and after prolonged storage at room temperature. In these conditions, an appreciable browning of brine, related to AA degradation, was also found. The use of benzoate alone had a significant influence on vegetable color, but flavor was not significantly affected at the benzoate levels tested. On the basis of the present study, benzoates should be removed from fermented vegetable formulations containing ascorbic acid to eliminate possible benzene formation during long-term storage.

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.