Manuel Joaquín Serradilla

Rapid differentiation of lactic acid bacteria from autochthonous fermentation of Iberian dry-fermented sausages

The populations of lactic acid bacteria (LAB) in different types of Iberian dry-fermented sausages from central-west Spain were identified. A simple and rapid electrophoretic method of whole-cell protein profiles was evaluated, correlating it with 16S rRNA gene sequence analysis and biochemical identification by API 50 CHL. A total of 96 isolates were identified by SDS-PAGE showing stable profiles corresponding to 30-45 polypeptides in the range 95-8kDa that were clearly different for the different species and were grouped with those of the 9 reference strains used in this study. The SDS-PAGE method showed that the predominant species were Pediococcus acidilactici (48%) followed by Lactobacillus plantarum (23%) and Lactobacillus brevis (18%). The identifications obtained by this approach were confirmed by sequencing the V2-V3 region of the 16S rRNA gene and by a BLAST search of the GenBank database. However, biochemical identifications by API 50 CHL showed different errors at the genus and species level. In sum, the SDS-PAGE analysis showed itself to be a rapid and accurate differentiation method for the most commonly encountered LAB isolates in dry-fermented sausages.

Safety and functional aspects of pre-selected lactobacilli for probiotic use in Iberian dry-fermented sausages.

The purpose of this study was to investigate lactobacilli for potential probiotic use in Iberian dry-fermented sausages. A total of 18 strains, previously selected, isolated from different sources were evaluated according to safety and functional characteristics including biogenic amines and d-lactic acid production, antibiotic susceptibility, haemolysis, cell adhesion, and antimicrobial activity against food-borne pathogens. The strains Lactobacillus reuteri PL519, L. reuteri PL542, and Lactobacillus fermentum HL57 were able to establish their self on the intestinal epithelium, and an inhibition of such pathogenic bacteria as Listeria monocytogenesin vitro. These strains were also considered safe to be used with regard to their low aminogenic potential and d-lactic acid production, antibiotic resistance pattern and haemolytic activity. Thus, they were selected as a potential probiotic meat starter culture suitable for manufacture of dry-fermented Iberian sausages.

Differentiation of Staphylococci from Iberian dry fermented sausages by protein fingerprinting.

The Staphylococci populations in different types of Iberian dry fermented sausages from central-west Spain were identified. A simple electrophoretic method of whole-cell proteins and extracellular protein profiling was evaluated for speed of identification. This study was correlated with a 16S rRNA gene sequence analysis and biochemical identification by API Staph. A total of 81 isolates were identified by SDS-PAGE of the whole-cell proteins. These showed stable profiles in the range 99-14kDa that were clearly different for the different species, and were grouped into clusters together with the profiles of the eight reference strains. SDS-PAGE of the extracellular protein extracts provided additional characteristic banding patterns for the characterization of the Staphylococcus species present. The whole-cell SDS-PAGE showed that the predominant species was Staphylococcus saprophyticus (61.7%) followed by Staphylococcus aureus (19.7%). The identifications were confirmed by the 16S rRNA gene sequencing and by a BLAST search of the GenBank database. However, the API Staph biochemical identifications were frequently erroneous at the species level. In sum, SDS-PAGE analysis showed itself to be rapid and accurate in identifying the most commonly encountered Staphylococcus isolates in dry fermented sausages.

Antioxidant and antimicrobial activity of natural phenolic extract from defatted soybean flour by‐product for stone fruit postharvest application

BACKGROUND Fresh fruit is highly perishable during storage and transport, so there has been growing interest in finding safe and natural antimicrobial compounds as a control tool. Phenolic compounds are secondary metabolites naturally present in vegetable material and have been associated with antimicrobial and antioxidant properties. Therefore, the aim of this study was to investigate the antioxidant capacity and potential antimicrobial effect of phenolic extract obtained from defatted soybean flour against selected pathogenic bacteria and microorganisms responsible of fruit decay. RESULTS Analysis of phenolic composition by HPLC-MS showed the presence of a wide range of compounds, with isoflavones and phenolic acids the main polyphenols identified. Furthermore, the phenolic extract had important antioxidant activity by two different assays. Related to antimicrobial activity, in vitro experiments demonstrated that phenolic extract displayed a high activity against the main foodborne pathogens, while a moderate inhibition was found against five spoilage yeasts and Monilia laxa and a scarce effect for Penicillium glabrum, Cladosporium uredinicola and Botrytis cinerea. Interestingly these compounds considerably inhibited the mycelial growth of Monilia laxa, in both in vitro and in vivo experiments. CONCLUSION The results of the present study revealed that defatted soybean flour is an important source of phenolic compounds with remarkable antimicrobial and antioxidant activity, suggesting the possibility of using them as natural additives in postharvest treatments to extend the shelf life of fruit.

Physicochemical and Nutritional Characterization of Brebas for Fresh Consumption from Nine Fig Varieties (Ficus carica L.) Grown in Extremadura (Spain)

The quality characteristics of brebas for fresh consumption from nine fig varieties at different commercial ripening stages were determined. Physicochemical and nutritional parameters were analyzed for both skin and flesh, and the findings were compared among varieties and ripening stages. The results revealed that the major nutrient components in brebas are sugars, such as glucose and fructose, and mineral elements, including K, Ca, P, and Mg. Most nutrients evaluated are important elements that contribute to the commercial quality of brebas. “Brown Turkey” and “Banane” varieties showed the highest weight and width. The concentrations of the monomer sugars studied were higher in flesh than skin, and the “Cuello Dama Blanco” and “Colar Elche” varieties showed the highest content of these sugars. The early ripening stage, coinciding with a fast increase in fruit size, was also associated with a higher fiber and protein contents, TA, and firmness for “Banane,” “Brown Turkey,” and “Blanca Betera” varieties. Conversely, the later ripening stage was related to a significant increase of TSS, MI, and color intensity. Finally, no clear changes in the concentrations of organic acids were observed between different varieties and commercial ripening stages.

Composition of the Cherry (Prunus avium L. and Prunus cerasus L.; Rosaceae)

This chapter provides a review of cherry composition with special focus on varietal differences. Botanical aspects of sweet and sour cherries are initially addressed, and main nutrients, such as carbohydrates, dietary fibers, fats, proteins, vitamins, and minerals, are described. A variety of phytochemicals (e.g., phenolics, anthocyanins, and flavonoids) contributing to functional properties of cherries are also discussed in this chapter. In addition, differences in the volatile compound profiles among cultivars and their impacts on sensorial properties of cherries are described. The influence of maturity stages on the compositional changes in the ‘Ambrunes’ cultivar is described in the last part of the chapter.

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.