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Short-chain fructooligosaccharides (ScFOS) are a group of linear fructose oligomers that include 1-kestose, 1-nystose and 1-β-fructofuranosylnystose. ScFOS, which naturally occur at low levels in different plant products, are of high interest as food ingredients because of their prebiotic character, organoleptic characteristics and technological properties. Two different industrial processes are used to achieve large-scale ScFOS production: inulin hydrolysis (enzymatic or chemical hydrolysis) or sucrose biotransformation by transfructosylation (enzymatic synthesis) using specific enzymes like fructosyltransferases and fructofuranosidases. Enzymatic ScFOS synthesis seems to be more advantageous than inulin hydrolysis since it is less expensive, and leads to lower molecular weight FOS. The biotechnological process described to carry out this catalysis includes the production of transfructosylation enzymes, separation, enzyme immobilisation and finally the ScFOS production and purification. Such ScFOS production processes may be conducted under submerged or solid-state fermentation under discontinuous or continuous conditions. Several methodologies with different economic/environmental costs and production yields have been described to carry out these ScFOS production stages, although industrial scale-up needs to be optimised. This review tries to address a revision about enzymatic ScFOS production methods and its scale-up to industrial levels.

El uso del agua marina desalinizada como una alternativa a los recursos de agua convencionales cada vez gana más interés debido al gran déficit hídrico de algunas zonas del planeta como es el caso de la cuenca mediterránea. Por ello, se estudió el efecto del riego con agua marina desalinizada, y de pozo, así como una mezcla de ambas (para reducir costes), sobre la calidad del tomate (una de las hortícolas con mayor tolerancia a la salinidad), cultivado en suelo normal o en hidroponía. El uso de agua marina desalinizada no afectó en gran medida a la calidad fisicoquímica del tomate (sólidos solubles, acidez titulable, firmeza y color). Por otra parte, el agua marina desalinizada aumentó la capacidad antioxidante total del tomate mientras que otros compuestos como la vitamina C no se vieron altamente afectados. En conclusión, el uso de agua marina desalinizada no compromete la calidad del tomate siendo incluso incrementadas las propiedades antioxidantes de esta hortícola de alto valor económico. Este estudio fue financiado a través del Programa Europeo LIFE Program de la Unión Europea por el proyecto DESEACROP (LIFE16-ENV-ES-000341).

The use of desalinated seawater (DSW) as an alternative to conventional water resources is gradually gaining more interest due to the strong water deficit and increasing pressure on water resources in semi-arid regions. Furthermore, the combination of this alternative irrigation with the hydroponic cultivation system would allow continuous production almost through the whole year and hydroponic-related high crop yield. Nevertheless, the effects of DSW irrigation in hydroponic systems on the product quality need to be firstly studied to avoid product quality losses. In this study, we evaluated the effects on the quality of two tomato cvs. (Ramyle and Racymo) of three different irrigation treatments (T1, DSW, T2, DSW/well water mix, and T3, well water) under hydroponic or traditional cultivation systems. The soluble solid content of samples (highly correlated to dry matter content) grown under hydroponic conditions and T3 irrigation showed the highest values (5.8 &deg, Brix) although such differences (&lt, 0.6 &deg, Brix) with T1 might not be sensorially appreciated. Similarly, although T3 samples showed higher acidity than T1 samples, such differences (0.06%) would be not appreciated by the consumer. Tomatoes grown in hydroponic conditions had 1.1&ndash, 1.2-fold higher firmness than conventional soil conditions showing hydroponic T3 samples had the highest value (21&ndash, 23 N). Tomato cv. Racymo displayed higher color index (chroma) than cv. Ramyle, registering hydroponic T1 samples the most intense red color correlated with the highest lycopene content of 41.1 mg/kg. T1 irrigation of tomatoes cv. Ramyle did not induce significant changes while differences lower than 10% were observed in the tomato cv. Racymo. The highest total antioxidant capacity, which was highly correlated to the total phenolic content (R2 = 0.80), was found for hydroponic T1 samples with 1637/1243 &micro, mol/kg for the tomato cvs. Ramyle/Racymo. Conclusively, the use of DSW would not compromise the consumer acceptance of tomatoes due to the low (not appreciable) quality differences, with even the total antioxidant capacity of these samples being increased. Furthermore, the mix of DSW with conventional water resources (lower cost) would not compromise the tomato quality.

Active packaging including encapsulated essential oils (EOs) may highly increase the shelf life of horticultural products due to the higher antimicrobial activity of EOs in the vapour phase through a controlled release from the packaging. In that sense, the aim of the present study was to study the effects of an active packaging (a cardboard box including a βcyclodextrin (βCD) inclusion complex with an EOs mix) on the quality of bell peppers (green, red and yellow) during storage at 8 °C (90 % relative humidity) up to 18 d. The EO mix (carvacrol:oregano:cinnamon 70:10:20 v:v:v) was efficiently encapsulated within the βCD inclusion complex by 94 %. Green, red and yellow peppers packaged within the active box showed 1–2 lower log units of enterobacteria than the control (without the active coating) after 11–18 d. Furthermore, green/red and yellow peppers showed lower mould counts (approximately 1 log unit) than control samples at days 6 and 11, respectively. The decay incidence of samples was also highly controlled by the active packaging with percentages lower than 5 % after 18 d while control samples showed decay incidences of 10–15 %. The use of this active box did not negatively affect the physicochemical quality of peppers even showing red and green peppers of the active box better firmness than control samples after 18 d. The shelf life of peppers stored within the active box reached 18 d while samples stored with the control box were rejected. Carvacrol residues in peppers were very low (below 1 mg kg−1) avoiding off-flavours according to sensory results. Conclusively, this active packaging allowed to extend the shelf life of green, red and yellow peppers for at least 18 d at 8 °C.

The present work studies the effect of acid shock on cell viability of Bacillus cereus and Bacillus weihenstephanensis. Experiments were performed by means of flow cytometry (FCM) combined with fluorescent labelling. Propidium iodide, for membrane evaluation, and carboxyfluorescein diacetate, for esterase activity were used for differential staining of both strains. pH values of 3.4, 3.8 and 4.2 were selected on the basis of previous screening tests. FCM analysis showed to clearly discriminate between different populations, viable and damage cells, leading to successful assessment of acid shock effect on B. cereus and B. weihenstephanensis vegetative cell viability. Cellular viability decreased at lower pH values and longer exposure times, being B. weihenstephanensis more acid resistant than B. cereus. Reliability of FCM analysis for detection of B. cereus and B. weihenstephanensis vegetative cells was compared with classical viable plate count techniques (VPC). Although FCM and VPC data were not directly correlated and classical analytical methods show higher reliability, FCM analysis provides high-speed information at real time on damage at single cell level, whereas VPC only gives an indication of cells able to grow at a certain time. These data could help to establish more accurately the potential risk associated to foods or processing conditions where pH is involved, taking damage into consideration.

An active cardboard tray coated with a water-based emulsion including encapsulated (in β−cyclodextrins (CDs)) essential oils (EOs) was used to study the quality changes of cherry tomatoes (flow-packaged using a macroperforated film) during storage up to 24 days at 8 °C. Commercial polyethylene and non-active cardboard trays were used as control materials. Firmness of samples was well maintained for 24 days, while decay incidence was reduced from 8% to

Application of essential oils (EOs) in vapour phase under vacuum conditions may increase the effectiveness of EOs to sanitize plant products. Different treatments with EOs vapor were studied in vitro and in vivo against saprophyte microflora and pathogens at laboratory, pilot plant and industrial scales. Vapor of carvacrol combinations with oregano and peppermint essential oils (80:20 v:v) showed the best microbial reductions up to 1.5 log units for mesophiles ( in vitro at laboratory scale), 0.9–3.9 log units for several isolated molds ( in vitro at pilot plant scale) and approximately 1 log unit for Listeria innocua ( in vivo at pilot plant scale). Particularly, carvacrol:oregano and carvacrol:peppermint vapors showed the highest mold log reductions (>3.3) for Botrytis cinerea , Alternaria alternata and Aspergillus niger while Fusarium spp. and Penicillium spp. showed lower reductions. EOs vapors concentrations lower than 0.5 mg L −1 did not achieve mold reductions higher than 0.2 log units while EOs vapors concentrations ≥10 mg L −1 did not increase the antifungal activity. Fresh cilantro treated at industrial scale with vapor of carvacrol:peppermint (less off-flavors than carvacrol:oregano) (80:20 v:v) at 8 mg L −1 under vacuum (adapting a vacuum cooling system) showed 0.8, 1.8 and 1.2 lower mesophiles, psychrophiles and enterobacteria log units, respectively, than untreated samples after 12 d at 2 °C of storage. Yeast and mold growth in cilantro was low throughout the studied period at storage temperature of 2 °C. Yellowing and browning of cilantro treated at 8 mg L −1 was also minimal, compared to the rest of treatments, after 12 d at 2 °C. In conclusion, the application of carvacrol:peppermint (80:20 v:v) vapor at 8 mg L −1 under vacuum in an industrial installation may extend the shelf life of fresh cilantro further than 12 d at 2 °C ensuring its microbial and visual quality.

Strains belonging to Bacillus cereus Group include six different species, among which are Bacillus thuringiensis, Bacillus weihenstephanensis, and Bacillus cereus sensu stricto, a causative agent of food poisoning. Sequence of the panC-housekeeping gene is used for B. cereus Group affiliation to seven major phylogenetic groups (I-VII) with different ecological niches and variations in thermal growth range and spore heat resistance of B. cereus Group microorganisms varies among phylogenetic groups. We assigned a selection of B. cereus sensu stricto strains related to food poisoning from the Spanish cultivar Collection (Valencia) to Group IV strains based on panC gene sequence. Thermal inactivation assays revealed variability of spore heat resistance within these Group IV strains. Adequate food sanitizing treatments therefore require fast and reliable identification of particular strains. In the present study, feasibility of genotyping via high-resolution melting (HRM) analysis was examined. HRM analysis of amplified polymorphic 16S-23 intergenic spacer region (ISR) region proved to be discriminatory for B. cereus sensu stricto strain typing, while two other polymorphic regions within the bacterial rRNA operon allowed differentiation between Bacillus species, demonstrating its applicability for discrimination on the species and strain level within B. cereus Group.

Stochastic models can be useful to predict the risk of foodborne illness. The presence of Bacillus cereus in liquid egg can pose a serious hazard to the food industry, since a mild heat treatment cannot guarantee its complete inactivation. However, most of the information available in the scientific literature is deterministic, including growth of B. cereus. In this paper, a stochastic approach to evaluate growth of B. cereus cells influenced by different stresses (presence of nisin and lysozyme separately or in combination) was performed, using an individual-based approach of growth through OD measurements. Lag phase duration was derived from the growth curves obtained. From results obtained, histograms of the lag phase were generated and distributions were fitted. Normal and Weibull distributions were ranked as the bestfit distributions in experiments performed at 25 °C. At 16 °C, lag values (obtained in presence of combinations of both antimicrobials) were also fitted by a Gamma distribution. Predictions were compared with growth curves obtained in liquid egg exposed to mild heat, nisin and/or lysozyme to assess their validity.

The microbial safety and stability of minimally processed foods are based on the application of combined preservative factors. Since microorganisms are able to develop adaptive networks to survive under conditions of stress, food safety may be affected, and therefore understanding of stress adaptive mechanisms plays a key role in designing safe food processing conditions. In the present study, the viability and the sublethal injury ofListeria monocytogenesexposed to moderate heat (55°C) and/or essential oil compounds (carvacrol and thymol, 0.3 mM) treatments were studied. Synergistic effects were obtained when combining mild heat (55°C) with one or both essential oil compounds, leading to inactivation kinetics values three to four times lower than when using heat alone. All the treatments applied caused some injury in the population. The injury levels ranged from around 20% of the surviving population under the mildest conditions to more than 99.99% under the most stringent conditions. Protein extracts of cells exposed to these treatments were analysed by two-dimensional gel electrophoresis. The results obtained revealed that stressed cells exhibited differential protein expression to control cells. The proteins upregulated under these stressing conditions were implicated, among other functions, in stress response, metabolism, and protein refolding.

The different strains of Bacillus cereus can grow at temperatures covering a very diverse range. Some B. cereus strains can grow in chilled food and consequently cause food poisoning. We have identified a new sensor/regulator mechanism involved in low-temperature B. cereus growth. Construction of a mutant of this two-component system enabled us to show that this system, called CasKR, is required for growth at the minimal temperature ( T min ). CasKR was also involved in optimal cold growth above T min and in cell survival below T min . Microscopic observation showed that CasKR plays a key role in cell shape during cold growth. Introducing the casKR genes in a Δ casKR mutant restored its ability to grow at T min . Although it was first identified in the ATCC 14579 model strain, this mechanism has been conserved in most strains of the B. cereus group. We show that the role of CasKR in cold growth is similar in other B. cereus sensu lato strains with different growth temperature ranges, including psychrotolerant strains.

[SPA]Los microorganismos pertenecientes al grupo Bacillus cereus poseen importancia económica y para la salud pública. De entre todos ellos, Bacillus cereus sensu stricto es el agente causal de enfermedades gastrointestinales y Bacillus weihenstephanensis es una especie psicrótrofa capaz de crecer a temperaturas entre 4 y 7ºC. Además, ambos son responsables de pérdidas económicas relevantes derivadas del deterioro de alimentos. Debido a su habilidad para formar endosporos altamente resistentes, estas especies son capaces de persistir en ambientes de producción de alimentos, contaminando aquellos productos que han sufrido un tratamiento térmico moderado. Además, se han aislado cepas psicrótrofas y algunas mesófílas a partir de alimentos refrigerados. En este contexto y con el fin de contribuir a la mejora de los sistemas de conservación de alimentos, lo que asegura la calidad microbiológica de los mismos, el objetivo principal de la presente tesis ha sido el estudio del impacto de factores ambientales relevantes, comúnmente denominados como barreras, en la supervivencia y el crecimiento de diferentes especies del grupo B. cereus. Así mismo, se han realizado estudios centrados en la evaluación de la idoneidad de métodos de identificación rápida de dichos microorganismos y de la fiabilidad de técnicas que permitan estudios de viabilidad bacteriana a nivel de células individuales. Los alimentos vegetales listos para consumir son altamente demandados en los países industrializados ya que, debido a su conservación mediante tratamientos térmicos moderados, mantienen una alta calidad sensorial y nutricional. Sin embargo, este procesado facilita la persistencia de los microorganismos esporulados y se han aislado diversas cepas de B. cereus a partir de estos productos.[ENG] Bacillus cereus group species range high in economical and medical importance. Among all of them, Bacillus cereus sensu stricto is the causative agent of gastrointestinal diseases and Bacillus weihenstephanensis is a psychrotrophic species able to grow in the range of 4-7ºC. Both species are also recognized as spoilage bacteria causing economic losses. Due to their ability to form highly resistant spores, these microorganisms may persist in the food environment and contaminate mildly heat treated products. Moreover, psychrotrophic and some mesophilic strains have been isolated from chilled foodstuffs. On this ground, to contribute to improve food preservation systems that ensure microbiological quality, the major aim of the present thesis was to study the impact of relevant environmental factors, commonly referred to as hurdles, on the ability to survive and grow of different species of B. cereus group and to assess novel methods for fast and reliable identification of these microorganisms as well as to test the feasibility of techniques used in viability studies at single cell level. Ready to eat vegetable foods are widely consumed in industrialized countries due to their tasty, healthy and wholesome attributes. However, B. cereus strains have been previously isolated from these mildly preserved foods., Universidad Politécnica de Cartagena

The effects of a cardboard active packaging were studied on the quality of fresh tomatoes during storage up to 22 days at 8 °C and after complimentary commercialisation periods (3 days at 25 °C). The inner surface coating of this active cardboard packaging included an essential oil-β-cyclodextrin inclusion complex. The physicochemical quality (soluble solid content, pH and titratable acidity), colour and firmness of tomatoes were not highly affected by the active packaging during cold storage and commercialisation periods. Particularly, tomato colour was better retained during the first 6 days of storage at 8 °C. The decay incidences of 3.7% and 36% from samples within the non-active box after 12 days+commercialisation period and 22 days at 8 °C were reduced to 2.4% and 22%, respectively, using the active box. Overall sensory perception of tomatoes, which was highly influenced by flavour, was still over the limit of usability after 22 days at 8 °C and the 12 days+commercialisation period when packaged within the active box. On the contrary, samples packaged within the non-active box were not marketable after 22 days and 12 days+commercialisation periods. Conclusively, the controlled release of essential oil vapours from the active box extended the shelf life of tomatoes up to 22 days at 8 °C and 12 days (8 °C)+commercialisation period. The very low essential oil residues in tomato fruits (lower than 1 μg g−1 during storage periods) were not detected as off-flavours by the sensory panel.