Reduction of the Bitter Taste in Packaged Natural Black Manzanilla Olives by Zinc Chloride.

The work assays the use of various concentrations of ZnCl2 (0.0-0.1%, w/v) in packaged natural black Manzanilla table olives. The transformations were followed for 4 months. The presence of Zn modified the leaching of total sugars (sucrose, glucose, fructose, and mannitol) into the brine, which decreased as the ZnCl2 content increased. Over the study, sucrose and glucose were exhausted while fructose, although consumed, left some final residues and the use of mannitol was limited. Titratable acidity was always gradually formed causing the subsequent pH decrease, which stabilized at ≈3.5. Acetic and mainly lactic acid were also formed during the assay, reaching the highest level of lactic acid in the 0.050% ZnCl2 treatment, followed by the Control. The acids were formed by lactic acid bacteria (LAB) (Lactobacillus pentosus, 39%, and Lactobacillus plantarum, 61%). However, the most outstanding Zn effect was found on the olive sensory characteristics: its presence markedly reduced the bitter notes, increased the overall appreciation, and the treatment containing 0.075% ZnCl2 had the highest scores in hardness, crunchiness, and overall appreciation. Therefore, the addition of ZnCl2 into packaged natural table olives may lead to healthy products with desirable sensory characteristics which, in turn, could promote consumption.

A Probabilistic Decision-Making Scoring System for Quality and Safety Management in Aloreña de Málaga Table Olive Processing.

Table olives are one of the most representatives and consumed fermented vegetables in Mediterranean countries. However, there is an evident lack of standardization of production processes and HACCP systems thus implying the need of establishing decision-making tools allowing their commercialization and shelf-life extension. The present work aims at developing a decision-making scoring system by means of a probabilistic assessment to standardize production process of Aloreña de Málaga table olives based on the identification of potential hazards or deficiencies in hygienic processes for the subsequent implementation of corrective measures. A total of 658 microbiological and physico-chemical data were collected over three consecutive olive campaigns (2014-2016) to measure the variability and relative importance of each elaboration step on total hygienic quality and product safety. Three representative companies were visited to collect samples from food-contact surfaces, olive fruits, brines, air environment, olive dressings, water tanks, and finished/packaged products. A probabilistic assessment was done based on the establishment of Performance Hygiene and Safety Scores (PHSS 0-100%) through a standardized system for evaluating product acceptability. The mean value of the global PHSS for the Aloreña de Málaga table olives processing (PHHSFTOT) was 64.82% (90th CI: 52.78-76.39%) indicating the high variability among facilities in the evaluated processing steps on final product quality and safety. Washing and cracking, and selection and addition of olive dressings were detected as the most deficient ones in relation to PHSSFi values (p < 0.05) (mean = 53.02 and 56.62%, respectively). The relative contribution of each processing step was quantified by different experts (n = 25) from the Aloreña de Málaga table olive sector through a weighted PHSS (PHSSw). The mean value of PHSSw was 65.53% (90th CI: 53.12-77.52%). The final processing steps obtained higher values for PHSSw being the finished product the most relevant one (mean = 18.44%; 90% CI: 10.34-25.33%). Sensitivity analysis concluded that intervention measures focused on reducing the contamination of washing brines could lead to an improvement of PHSSFTOT value to 67.03%. The present work can be potentially applied in the Aloreña de Málaga table olive food sector for improving food quality and safety assurance.

Microbiological and Physicochemical Changes in Natural Green Heat-Shocked Aloreña de Málaga Table Olives.

Preserving the highly appreciated natural freshness of Aloreña de Málaga table olives and preventing their progressive darkening during processing is a major challenge. In this work, heat-shocked (60°C, 5 min) fruits were processed according to the three denominations referred to in the Protected Designation of Origen (cured, fresh green, and traditional) and their characteristics compared with those that followed the habitual industrial process (controls). The results revealed that the effects of the heat treatment on the evolution of pH, titratable acidity, salt, sugar, organic acid, ethanol content, texture, and color of fruits as well as on microbial populations (yeasts and lactic acid bacteria) were slight in the case of the fresh green and cured presentations. However, the differences between heat-shocked and its control were remarkable in the traditional process. Notably, the heat treatment favored lactic acid fermentation, retention of the green appearance of the fruits, stability during packaging, and led to the highest sensory evaluation. The metagenomic analysis carried out at the end of the fermentation revealed the presence in all samples of three genera (Lactobacillus, Pediococcus, and Celerinatantimonas) which encompassed most of the sequences. The number of Lactobacillus sequences was statistically higher (p ≥ 0.05) in the case of traditional heat-shocked fruits than in its control.

Assessing the Challenges in the Application of Potential Probiotic Lactic Acid Bacteria in the Large-Scale Fermentation of Spanish-Style Table Olives.

This work studies the inoculation conditions for allowing the survival/predominance of a potential probiotic strain (Lactobacillus pentosus TOMC-LAB2) when used as a starter culture in large-scale fermentations of green Spanish-style olives. The study was performed in two successive seasons (2011/2012 and 2012/2013), using about 150 tons of olives. Inoculation immediately after brining (to prevent wild initial microbiota growth) followed by re-inoculation 24 h later (to improve competitiveness) was essential for inoculum predominance. Processing early in the season (September) showed a favorable effect on fermentation and strain predominance on olives (particularly when using acidified brines containing 25 L HCl/vessel) but caused the disappearance of the target strain from both brines and olives during the storage phase. On the contrary, processing in October slightly reduced the target strain predominance on olives (70-90%) but allowed longer survival. The type of inoculum used (laboratory vs. industry pre-adapted) never had significant effects. Thus, this investigation discloses key issues for the survival and predominance of starter cultures in large-scale industrial fermentations of green Spanish-style olives. Results can be of interest for producing probiotic table olives and open new research challenges on the causes of inoculum vanishing during the storage phase.

In silico Logistic Model for Table Olive Related Microorganisms As a Function of Sodium Metabisulphite, Cinnamaldehyde, pH, and Type of Acidifying Agent.

A probabilistic/logistic model, based on binary data (growth/no growth), was used to assess the effects of sodium metabisulphite (SM) and cinnamaldehyde (CIN; 0-1000 mg/L) against the main microbial groups found in table olive environment [lactic acid bacteria (LAB), yeasts, and Enterobacteriaceae], according to pH (range 3.5-5.0), and type of acidifying agent (HCl or pyruvic acid). The inhibitory effect of SM depended on the pH while that of CIN was scarcely influenced by it (except for LAB). LAB were more sensitive to SM, while yeasts were to CIN. The use of pyruvic acid for correction of pH always produced a reduction (compared to HCl) of the inhibitory power of both preservatives. The in silico models for HCl showed that, at pH 4.0, and growth probability 0.01, the LAB population might be inhibited by the presence in the medium of 150 mg/L SM or 1000 mg/L CIN, while in the case of yeasts, 450 mg/L SM, or 150 mg/L CIN are required. No growth of Enterobacteriaceae was observed at this (or lower) pH level. The results obtained may contribute to the stabilization of non-thermally treated table olive packaging.

RT-PCR-DGGE Analysis to Elucidate the Dominant Bacterial Species of Industrial Spanish-Style Green Table Olive Fermentations.

This paper describes the dominant bacterial species metabolically active through the industrial production of Spanish-style Manzanilla and Gordal olives. For this purpose, samples (brines and fruits) obtained at 0, 15, and 90 fermentation days were analyzed by a culture-independent approach to determine viable cells by reverse transcription of RNA and further PCR-DGGE analysis, detecting at least 7 different species. Vibrio vulnificus, Lactobacillus plantarum group, and Lactobacillus parafarraginis were present in samples from both cultivars; Lactobacillus sanfranciscensis and Halolactobacillus halophilus were detected only in Gordal samples, while Staphylococcus sp. was exclusively found at the onset of Manzanilla fermentations. Physicochemical data showed a typical fermentation profile while scanning electron microscopy confirmed the in situ biofilm formation on the olive epidermis. Different Bacillus, Staphylococcus, and Enterococcus species, not detected during the fermentation process, were also found in the solid marine salt used by the industry for preparation of brines. Elucidation of these non-lactic acid bacteria species role during fermentation is then an appealingly challenge, particularly regarding safety issues.

Survival of pathogenic and lactobacilli species of fermented olives during simulated human digestion.

The present survey uses a dynamic gastric and small intestinal model to assess the survival of one pathogenic (Escherichia coli O157:H7 EDL 933) and three lactobacilli bacteria with probiotic potential (Lactobacillus rhamnosus GG, L. pentosus TOMC-LAB2, and L. pentosus TOMC-LAB4) during their passage through the human gastrointestinal tract using fermented olives as the food matrix. The data showed that the survival of the E. coli strain in the stomach and duodenum was very low, while its transit through the distal parts (jejunum and ileum) resulted in an increase in the pathogen population. The production of Shiga toxins by this enterohemorrhagic microorganism in the ileal effluents of the in vitro system was too low to be detected by ELISA assays. On the contrary, the three lactobacilli species assayed showed a considerable resistance to the gastric digestion, but not to the intestinal one, which affected their survival, and was especially evident in the case of both L. pentosus strains. In spite of this, high population levels for all assayed microorganisms were recovered at the end of the gastrointestinal passage. The results obtained in the present study show the potential use of table olives as a vehicle of beneficial microorganisms to the human body, as well as the need for good hygienic practices on the part of olive manufacturers in order to avoid the possibility of contamination by food-borne pathogens.

Fortification of table olive packing with the potential probiotic bacteria Lactobacillus pentosus TOMC-LAB2.

Dairy products are currently the main carriers of probiotic microorganisms to the human body. However, the development of new matrices for probiotic delivery is convenient for intolerant to milk (or its derivatives) and those requiring low-cholesterol diet consumers. The present work focused on the fortification of previously fermented green Spanish style olives with the autochthonous putative probiotic bacteria Lactobacillus pentosus TOMC-LAB2. The fortification was carried out by inoculating the bacteria into the packing brines using Manzanilla fruits from three different processes: (i) spontaneously fermented (F1), (ii) fermented using L. pentosus TOMC-LAB2 as starter (F2), and (iii) spontaneously fermented and then thermally treated (F3). Data showed that all inoculated treatments had higher population levels (5.49, 4.41, and 6.77 log10 cfu/cm(2)) than their respective controls (1.66, 4.33, and 0.0 log10 cfu/cm(2), for F1, F2, and F3 treatments, respectively). The presence of L. pentosus TOMC-LAB2 on olive surface was confirmed by rep-PCR, with a recovery frequency at the end of the shelf life (200 days) of 52.6, 57.9, and 100.0% for F1, F2, and F3 treatments, respectively. Thus, results obtained in this work show the ability of this microorganism to survive under packing conditions for long period of times as well as to colonize the olive surface which is the food finally ingested by consumers. This opens the possibility for the development of a new and simply probiotic fortified olive product.

Potential benefits of the application of yeast starters in table olive processing.

Yeasts play an important role in the food and beverage industry, especially in products such as bread, wine, and beer, among many others. However, their use as a starter in table olive processing has not yet been studied in detail. The candidate yeast strains should be able to dominate fermentation, together with lactic acid bacteria, but should also provide a number of beneficial advantages. Technologically, yeasts should resist low pH and high salt concentrations, produce desirable aromas, improve lactic acid bacteria growth, and inhibit spoilage microorganisms. Nowadays, they are being considered as probiotic agents because many species are able to resist the passage through the gastrointestinal tract and show favorable effects on the host. In this way, yeasts may improve the health of consumers by means of the degradation of non-assimilated compounds (such as phytate complexes), a decrease in cholesterol levels, the production of vitamins and antioxidants, the inhibition of pathogens, an adhesion to intestinal cell line Caco-2, and the maintenance of epithelial barrier integrity. Many yeast species, usually found in table olive processing (Wickerhamomyces anomalus, Saccharomyces cerevisiae, Pichia membranifaciens, and Kluyveromyces lactis, among others), have exhibited some of these properties. Thus, the selection of the most appropriate strains to be used as starters in this fermented vegetable, alone or in combination with lactic acid bacteria, is a promising research line to develop in the near future.