Evaluation of Tunisian Olive Leaf Extracts to Reduce the Bioavailability of Acrylamide in Californian-Style Black Olives

The aim of this work was analyzing the use of olive leaf extracts (OLE) obtained from two local Tunisian olive tree cultivars 'Chemlali' and 'Sayali' to reduce the acrylamide in Californian-style black olives. The phenol profile, antioxidant, and antibacterial activity of the two OLE extracts were evaluated. The principal phenols found were hydroxytyrosol (1809.6 ± 25.3 mg 100 g^-1), oleuropein (2662.2 ± 38 mg 100 g^-1) and luteolin-7-O-glucoside (438.4 ± 38 mg 100 g^-1) presented higher levels in 'Sayali' variety. Small differences were observed between the two kinds of extracts used; the greatest activity of OLE was observed against S. choleraesuis, with values up to 50% inhibition. The extract of 'Chemlali' cultivar was added to the Californian-style table olive, improving its phenol content and its antioxidant characteristics without negatively affecting its sensorial characteristics; these olives showed the highest firmness and proper quality characteristics. The gastrointestinal activity on the acrylamide concentration showed a partial degradation of this compound through the digestion, although the addition of the extract does not seem influence in its gastrointestinal digestion. These findings prove the usefulness of by-products to generate a high-quality added-value product, and this would also be relevant as a step towards a more sustainable, circular economy model.

Application of Electronic Nose to Discriminate Species of Mold Strains in Synthetic Brines

The chemical composition of the brine for Spanish-style table olives plays a crucial role during the fermentation process. Traditional laboratory analysis requires a high consumption of reagents, highly qualified personnel, sophisticated equipment, long analysis times, and large amounts of samples. Analysis carried out using an electronic nose (E-nose) offers an alternative, non-destructive technique and is useful in determining alterations in brines caused by microorganisms. In the present research, nine mold strains isolated from spoiled olives were inoculated in synthetic brines to determine the effect of microbial development on sensory quality, volatile profile, and the capacity of E-nose to discriminate altered brines from the healthy ones. The brines inoculated with the mold strains presented negative attributes related to aromas of mold, wood, leather, rancidity and, organic solvents among others. The highest intensity of defect was presented by the brines inoculated with the strains Galactomyces geotricum (G.G.2); three Penicillium expansum (P.E.3, P.E.4, and P.E.20); one Penicillium glabrum (P.G.19); three Aspergillus flavus (A.F.9, A.F.18, and A.F.21); and one Fusarium solani (F.S.11). A total of 19 volatile compounds were identified by gas chromatography. Sensory analysis allowed us to classify the synthetic brines based on the degree of alteration produced by the mold strains used. Also, the E-nose data were able to discriminate the inoculated brines regardless of the intensity of the defect. These results demonstrate the capacity of the E-nose to discriminate alterations in brines produced by molds, thereby making it a useful tool to be applied during the elaboration process to detect early alterations in table olive fermentation.

Effect of High Hydrostatic Pressure in the Storage of Spanish-Style Table Olive Fermented with Olive Leaf Extract and Saccharomyces cerevisiae

Olives treated according to the Spanish-style are firstly treated with caustic soda and then fermented in brine to reduce phenols. Next, olives are packed and subjected to pasteurization. The effect of different high hydrostatic pressure treatments (400 MPa, 4 and 6 min) was evaluated in Spanish-style table olives fermented with olive leaf extract (OLE) and S. cerevisiae compared with thermal pasteurization (P) at 80 °C for 15 min. HHP and P led to a significant reduction in yeast and aerobic mesophiles after the conservation treatment and during storage (300 days). The physical-chemical properties changed slightly during storage, except for olive hardness; olives treated with HHP presented a higher hardness than pasteurized ones. The CIELAB parameter L* decreased until day 300 in most of the treatments, as well as phenols. The HHP treatment led to significantly higher contents of phenolics (even during storage) than olives submitted to P. Some sensory attributes (colour, aspect, hardness, and overall evaluation) decreased during storage. P treatment caused a decrease in appearance, aroma, hardness, and overall evaluation compared to olives treated with HHP. Thus, the application of HHP in table olives to increase the shelf-life can be considered a valid alternative to P.

Chemical Composition and Functional Properties of Dietary Fibre Concentrates from Winemaking By-Products: Skins, Stems and Lees

The objective of this study was to evaluate, from a technological and nutritional point of view, the chemical composition and functional properties of the industrial winemaking by-products, namely skins, stems and lees. The chemical and physical characteristics, as well as the functional properties (fat and water retention and swelling capacity, antioxidant capacity, and their prebiotic effect), of the dietary fibre of these by-products were studied. The results showed that the skins, stems, and lees are rich in fibre, with the stem fibre containing the highest amounts of non-extractable polyphenols attached to polysaccharides with high antioxidant activity and prebiotic effect. Lee fibre had the highest water retention capacity and oil retention capacity. The results reveal that winemaking by-products could be used as a source of dietary fibre with functional characteristics for food applications.

Addition of Grape Skin and Stems Extracts in Wines during the Storage to Reduce the Sulfur Dioxide: Impact on Red Wine Quality

This study aimed to evaluate the usefulness of bioactive extracts obtained from red wine by-products, such as grape skins and stems, for reducing or eliminating the use of SO2 in red wine production. Special attention was focused on guaranteeing the microbiological stability of the red wines and protecting them against oxidation. Therefore, the antioxidant and antimicrobial activities of the extracts and red wines were studied. Red grape stems and skins, by-products of the wine industry, from six types of monovarietal wines, were used. Extracts obtained from stems displayed higher concentrations of total phenolic compounds and higher in vitro antioxidant activity. Both stem and skin extracts demonstrated higher antimicrobial activity against pathogenic bacteria and lower activity against yeasts. In the wines produced, higher antimicrobial and antioxidant activities were observed, mainly in the skin extract batches. This study highlights that bioactive extracts obtained from by-products of wine making could be used to reduce or eliminate the use of SO2 in wine production. In this way, healthier red wines could be obtained while guaranteeing their microbiological stability and protecting them from oxidation. Furthermore, the use of these by-products is strongly associated with the circular economy, as they could help to reduce the environmental impact of the wine industry.

Effect of olive leaf extract combined with Saccharomyces cerevisiae in the fermentation process of table olives

Yeasts have a great importance in the table olives quality and have been proved more and more as starter cultures. Moreover, the addition of olive leaf extract (OLE) could enhance the nutritional value of table olives, but there are no studies in which added OLE has been combined with yeasts during fermentation. The aim of this work was to determine if the quality and functional value of table olives increases when OLE and a yeast starter are used during a Spanish-style olive fermentation process. Several combinations were used: (1) fermentations trials with OLE combined with a strain of Saccharomyces cerevisiae; (2) fermentations with OLE; (3) control fermentations, with no extract or starter culture. During fermentation performed with the addition of OLE and yeasts, the yeast number remained stable for most of the time, resulting in a slight decrease of yeasts by the end of the process. The phenolic profile of olive flesh and brines of the trials was analysed during the fermentation. The addition of OLE increased the concentration of phenols in olive flesh and brines at the end of the fermentation; in these fermentations, hydroxytyrosol was the most abundant, at around 1700 mg/kg in olive flesh and 3500 mg/L in brines olive flesh, whereas in the control fermentation the concentrations were around 900 mg/kg and 2500 mg/L, respectively. In spite of adding OLE, the fermentation resulted in olives without bitterness. We can conclude that yeast inoculation combined with OLE improves safety, nutritional value and other properties of the final product, without affecting its sensorial qualities.

Spoilage yeasts: What are the sources of contamination of foods and beverages?

Foods and beverages are nutrient-rich ecosystems in which most microorganisms are able to grow. Moreover, several factors, such as physicochemical characteristics, storage temperature, culinary practices, and application of technologies for storage, also define the microbial population of foods and beverages. The yeast population has been well-characterised in fresh and processed fruit and vegetables, dairy products, dry-cured meat products, and beverages, among others. Some species are agents of alteration in different foods and beverages. Since the most comprehensive studies of spoilage yeasts have been performed in the winemaking process, hence, these studies form the thread of the discussion in this review. The natural yeast populations in raw ingredients and environmental contamination in the manufacturing facilities are the main modes by which food contamination occurs. After contamination, yeasts play a significant role in food and beverage spoilage, particularly in the alteration of fermented foods. Several mechanisms contribute to spoilage by yeasts, such as the production of lytic enzymes (lipases, proteases, and cellulases) and gas, utilisation of organic acids, discolouration, and off-flavours. This review addresses the role of yeasts in foods and beverages degradation by considering the modes of contamination and colonisation by yeasts, the yeast population diversity, mechanisms involved, and the analytical techniques for their identification, primarily molecular methods.

Application of ISSR-PCR for rapid strain typing of Debaryomyces hansenii isolated from dry-cured Iberian ham

Yeast populations of dry-cured Iberian ham isolated from seven industries in the province of Badajoz were characterized by ISSR-PCR using the (CAG)4 primer and PCR-RFLP of the ITS1-5.8S rRNA-ITS2 fragment, and identified by DNA sequencing. A total of 242 isolates were analyzed, indicating the primary species present was Debaryomyces hansenii at 80.9% of the isolates followed by Candida zeylanoides at 10.3% of the isolates. The remainders of isolates were identified as Yamadazyma triangularis, Sporobolomyces roseus, Meyerozyma guilliermondii, Rhodotorula slooffiae, and Cryptococcus victoriae. The ISSR-PCR method was a fast and reliable method which was able to discriminate species at a level comparable to restriction analyses of the ITS1-5.8S rRNA-ITS2 region. This method allowed for strain typing of D. hansenii, yielding 29 different PCR patterns within 196 isolates. Moreover, ISSR-PCR using the (CAG)4 primer indicated that this technique could be a promising tool for rapid discrimination of yeast starter cultures and spoilage species in dry-cured Iberian ham.

[Nutritional evaluation of adolescent students from Extremadura based on anthropometric measurements]

INTRODUCTION AND OBJECTIVES

Nutrition is one of the pillars for proper body development and optimal nutritional status. Anthropometric methods are most commonly used for body composition analysis and are an essential part in the assessment of the nutritional status of individuals and population groups. This study aims to assess the nutritional status of adolescents from Extremadura (Spain); to determine variations in body composition according to the percentiles obtained; and to propose these values as a reference to the nutritional status of the adolescent population in Extremadura.

MATERIAL AND METHODS

A cross sectional study in the community of Extremadura was performed, including a total of 816 students of Secondary School Education of both sexes; and of all ages in the adolescence stage. The selected secondary schools belonged to populations of different sizes (less than 5,000 to more than 60,000 inhabitants). From the measurements taken, different anthropometric indices were determined and the percentiles 3, 10, 25, 50, 75, 90, 95 and 97 for weight, height and complexion were found.

RESULTS AND CONCLUSIONS

There were significant gender differences for height, weight, triceps skinfold, arm muscle area and arm fat area. Boys showed greater figures for height, weight and arm muscle area; however, the triceps skinfold and arm fat area was higher in girls. When compared to other national studies, the average height of our population was lower by about 3 cm in both sexes; the average weight was similar, but our adolescents had a higher proportion of fat in the arm. Extremadura girls seem to have a faster growth, reaching final height at an earlier age than the national average, although this height is below average. The boys had a continuous growth in all ages, maintaining national averages.

Identification and characterization of yeast isolated from the elaboration of seasoned green table olives

The purpose of this study was to investigate the yeast population during the processing of green table olives. In the fresh olives, yeast were found at concentrations of around 3.0 log cfu/g, with Cryptococcus spp. being predominant. In the brine, the yeast concentrations were greater than 4.9 log cfu/ml, with Pichia anomala, Kluyveromyces marxianus, and Saccharomyces cerevisiae being the predominant species. Unlike the yeast isolated from the fresh olives, the strains obtained from the olive brine mostly showed low pectolytic but high catalase activities. Some of these strains also exhibited other biochemical desirable properties for the fermentation of green table olives, including their lipolytic activities and their assimilation or production of organic acids in the brine. Seven strains in particular of P. anomala, K. marxianus, S. cerevisiae, and Candida maris showed the best properties for use in trials as starter culture in pilot fermenters.

Cellular death of two non-Saccharomyces wine-related yeasts during mixed fermentations with Saccharomyces cerevisiae

The early death of two non-Saccharomyces wine strains (H. guilliermondii and H. uvarum) during mixed fermentations with S. cerevisiae was studied under enological growth conditions. Several microvinifications were performed in synthetic grape juice, either with single non-Saccharomyces or with mixed S. cerevisiae/non-Saccharomyces inocula. In all mixed cultures, non-Saccharomyces yeasts grew together with S. cerevisiae during the first 1-3 days (depending on the initial inoculum concentration) and then, suddenly, non-Saccharomyces cells began to die off, regardless of the ethanol concentrations present. Conversely, in both non-Saccharomyces single cultures the number of viable cells remained high (ranging 10(7)-10(8) CFU ml(-1)) even when cultures reached significant ethanol concentrations (up to 60-70 g l(-1)). Thus, at least for these yeast strains, it seems that ethanol is not the main death-inducing factor. Furthermore, mixed cultures performed with different S. cerevisiae/ H. guilliermondii inoculum ratios (3:1; 1:2; 1:10; 1:100) revealed that H. guilliermondii death increases for higher inoculum ratios. In order to investigate if the nature of the yeast-yeast interaction was related or not with a cell-cell contact-mediated mechanism, cell-free supernatants obtained from 3 and 6 day-old mixed cultures were inoculated with H. guilliermondii pure cultures. Under these conditions, cells still died and much higher death rates were found for the 6 days than for the 3 day-old supernatants. This strongly indicates that one or more toxic compounds produced by S. cerevisiae triggers the early death of the H. guilliermondii cells in mixed cultures with S. cerevisiae. Finally, although it has not been yet possible to identify the nature of the toxic compounds involved in this phenomenon we must emphasise that the S. cerevisiae strain used in the present work is killer sensitive with respect to the classical killer toxins, K1, K2 and K28, whereas the H. guilliermondii and H. uvarum strains are killer neutral.

Identification of fungal contamination and determination of mycotoxigenic molds by micellar electrokinetic capillary chromatography in smoked paprika

The purpose of this work was to analyze the fungal contamination in smoked and unsmoked paprika processed from different cultivars of pepper and to investigate the ability of these and other mycotoxigenic molds to grow and synthesize mycotoxins in smoked paprika. Eighteen mycotoxins were evaluated using micellar electrokinetic capillary chromatography. No relevant differences were found in fungal contamination between smoked and unsmoked paprika. The number of yeasts obtained was low, ranging from 0.4 to 3.29 log CFU g(-1); most of the yeast strains were identified as Cryptococcus spp. followed by Candida spp. All mold counts were <4 log CFU g(-1). Aspergillus, Cladosporium, Penicillium, and Fusarium were the predominant hyphomycete genera. Six mycotoxins were identified in the extracts of several strains isolated from paprika and incubated on malt extract agar. Penicillium expansum followed by Penicillium citrinum and Penicillium raistrickii were the dominant mycotoxigenic fungi isolated. Most of themycotoxin-producing fungi produced detectable amounts of mycotoxins when grown on paprika agar.