Identification of New Coloured Anthocyanin–Flavanol Adducts in Pressure-Extracted Pomegranate (<Emphasis Type=BoldItalic>Punica granatum</Emphasis> L.) Juice by High-Performance Liquid Chromatography/Electrospray Ionization Mass Spectrometry

Pomegranate (Punica granatum L.) juice, obtained by pressure extraction of the whole fruit, contains coloured flavanol–anthocyanin adducts (the flavanol occupies the upper part of the dimmer) from the direct condensation between anthocyanidins delphinidin, cyanidin and pelargonidin and flavan-3-ols (epi)gallocatechin, (epi)catechin and (epi)afzelechin. The presence of adducts between these same flavanols and anthocyanidins, but belonging to the coloured anthocyanin–flavanol adduct type (anthocyanin occupies the upper part of the dimmer) has been revealed by reversed-phase liquid chromatography coupled to tandem mass spectrometry (ion trap), with positive electrospray ionization (LC–ESI/MS ⁿ ). These new adducts are isotopic with their corresponding counterparts (flavanol–anthocyanin adducts) and indistinguishable from them by comparison of the mass spectra from the MS² of the isotopic parent ions. However, they can be distinguished by comparison of the mass spectra from the MS³ of their corresponding isotopic aglycons. Hence, the MS³ of the aglycon from a given flavanol–anthocyanin adduct always yields a mass spectrum containing five characteristic ions, the three with smaller m/z being only dependent on the anthocyanidin and the other two on both the anthocyanidin and the flavanol. In contrast, the mass spectrum from the MS³ of the aglycon of its counterpart anthocyanin–flavanol adduct gives only two of the above five characteristic ions, where the ion with smaller m/z only depends on the anthocyanidin and the other on both the anthocyanidin and the flavanol. Ten 3-hexoside derivatives of coloured anthocyanin–flavanol adducts were detected in pomegranate juice being reported for the first time this type of adducts from a natural source.     

Updated knowledge about the presence of phenolic compounds in wine

Phenolic compounds are partly responsible for the color, astringency, and bitterness of wine, as well as for numerous physiological properties associated with wine consumption. Mass spectrometry has allowed for great progress in the identification and characterization of wine polyphenols. The aim of the present article is to summarize the numerous advances recently achieved in this field. The main type of phenolic compounds found in wine, including hydroxybenzoic and hydroxycinnamic acids, stilbenes, flavones, flavonols, flavanonols, flavanols, and anthocyanins, are firstly described. Chemical reactions and mechanisms involving phenolic compounds during winemaking are also extensively discussed, including enzymatic and chemical oxidation reactions, direct and acetaldehyde-mediated anthocyanin-tannin condensation reactions, acetaldehydemediated and glyoxylic acid-mediated tannin-tannin condensation reactions and, C-4/C-5 anthocyanin cycloaddition reactions with 4-vinylphenols, vinylflavanols and pyruvic acid, among others, leading to the formation of pyranoanthocyanins. Useful mass spectral data of well-known and novel phenolic compounds recently identified in wine, and details related to their fragmentation pathway according to different ionization techniques, are given.     

Quality assessment of commercial paprikas

Several quality parameters of smoked, oven‐dried and sun‐dried paprikas were studied. Smoked paprikas showed the highest American Spice Trade Association (ASTA) units and pigment concentrations, whereas oven‐dried paprikas showed the best browning index and red/yellow pigment ratio, and sun‐dried paprikas had the highest redness for reflected colour. The colour stability results showed drastic overall colour change (ΔE) and decreased redness and ASTA units of the sun‐dried and oven‐dried paprikas after two and 5 days of UV exposure. Degradation of the smoked paprika colour parameters was progressive, and they showed less degradation even after 30 days. The evaluation of the antioxidant activity showed higher DPPH radical‐scavenging capacity in the smoked samples. The profiles of volatile phenolic compounds of the smoked samples are responsible for the differences in the antioxidant capacity. The great differences in colour stability and antioxidant activity make smoked paprika the best choice for use in the food industry.     

Development of a Hyperspectral Computer Vision System Based on Two Liquid Crystal Tuneable Filters for Fruit Inspection. Application to Detect Citrus Fruits Decay

Hyperspectral systems are characterised by offering the possibility of acquiring a large number of images at different consecutive wavebands. To ensure reliable and repeatable results using this kind of optical sensors, the intensity shown by the objects in the different spectral images must be independent from the differences in sensitivity of the system for the different wavelengths. The spectral efficiency of the acquisition devices and the spectral emission of the lighting system vary across the spectrum and the images, and therefore the results can reproduce these variations if the system is not properly calibrated and corrected. This is particularly complex, when several LCTF devices are used to obtain large spectral ranges. This work presents the development of a hyperspectral system based on two liquid crystal tuneable filters for the acquisition of images of spherical fruits. It also proposes a methodology for acquiring and segmenting images of citrus fruits aimed at detecting decay in citrus fruits that has been capable of correctly classifying 98 % of pixels as rotten or non-rotten and 95 % of fruit.     

Hyperbaric storage at and above room temperature of a highly perishable food

Hyperbaric storage at naturally variable room temperature (RT) conditions (18–21 °C) and above (30 °C) was evaluated as a possible new food preservation method, regardless of temperature. Preservation of watermelon juice (used as a case study of a highly perishable food) at RT and 5 °C at atmospheric pressure was compared to preservation under 100 MPa at RT. After 8 h of hyperbaric storage at 100 MPa, the initial microbial loads of the watermelon juice were reduced by 1 log unit for total aerobic mesophiles, and 1–2 log units for Enterobacteriaceae and yeasts and moulds, to levels of about 3 log units for the former and below the detection limit for the latter, and remained thereafter unchanged up to 60 h. Similar results were obtained at 30 °C at 100 MPa after 8 h. At atmospheric pressure at RT (24 h) and 30 °C (8 h), microbial levels were already above quantification limits and unacceptable for consumption. Furthermore, pressure attenuated the increase in titratable acidity verified at atmospheric pressure, but caused higher colour changes, especially a higher lightness and a lower browning degree. Post-hyperbaric storage at 5 °C revealed an extended shelf life, as an additional benefit of hyperbaric storage. These results show that hyperbaric storage is a very promising food preservation methodology.     

Comparative Analysis of Antioxidative Activity of Flavonoids Using HPLC–ED and Photometric Assays

The present investigation reports on the application of a new antioxidant activity assay for the examination of flavonoids. It has been shown that the high-performance liquid chromatography with electrochemical detection (HPLC–ED) measurements allow to obtain additional information about the antioxidative properties of pure compounds by measuring their half-wave potential, the chromatographic peak height, and the product of the peak height and exponent of potential. In comparison to the classical electrochemical measurements, the HPLC–ED is characterized by a much smaller detection limit. The results were compared with the standard photometric measurement based on 1,1-diphenyl-2-picrylhydrazyl radicals. The possible antioxidant activity forecasting is also discussed.     

Characterization of Microencapsulated Rosemary Essential Oil and Its Antimicrobial Effect on Fresh Dough

This study aimed to characterize rosemary essential oil particles obtained by spray-drying and to evaluate their antimicrobial activity. Measurements of mycelial growth of Penicillium and Aspergillus fungi, isolated from fresh dough, were made applying oil concentrations of 1.0, 5.0, 10.0, 20.0, and 50.0 μL/mL. Fungi and yeast counts in the fresh dough submitted to the control (no oil), pure oil, and microencapsulated oil treatments were also conducted. The microcapsules showed 50 % oil retention after drying, and the major oil components identified were 1,8-cineole (29.0 %), camphor (26.6 %), and α-pinene (10.6 %). The analysis of the particles revealed surfaces without fissures, with a mean particle size of 12.2 μm and presenting an amorphous structure. The growth inhibiting effect of Penicillium sp. fungus, compared to the control, was verified at concentrations of 1.0, 5.0, and 10.0 μL/mL rosemary essential oil, which did not differ among them. For Aspergillus sp., the application of 10.0 μL/mL oil provided greater inhibition compared to 1.0 and 5.0 μL/mL. Complete inhibition occurred with the application of 50.0 μL/mL for both fungal genera tested. At 8 days of dough storage at 25 °C, a decrease of at least 0.7 and 1.5 log cycles of fungal growth was observed in the dough with pure oil and that with microencapsulated oil, respectively, relative to the control. The microencapsulation process retained the antimicrobial property of rosemary essential oil and provided further extension of this activity over time when applied to fresh dough.     

Continuous-Flow UV Liquid Food Pasteurization: Engineering Aspects

Ultraviolet (UV)-C treatments are a promising technology for liquid food pasteurization as an alternative to heat treatments. However, the design of efficient UV reactors to reduce pertinent microorganisms and comply with current food safety goals is still an engineering challenge due to the low penetration depth of UV light in liquid foods with high UV absorbance and suspended particles, and the variations in the residence time of the product in the UV reactors. This review focuses on physical aspects of UV radiation related to the essential product and processing parameters for the design of UV reactors. The UV equipment available for liquid food processing is described and the main drawbacks and advantages are discussed.     

The genome of wine yeast Dekkera bruxellensis provides a tool to explore its food-related properties

The yeast Dekkera/Brettanomyces bruxellensis can cause enormous economic losses in wine industry due to production of phenolic off-flavor compounds. D. bruxellensis is a distant relative of baker's yeast Saccharomyces cerevisiae. Nevertheless, these two yeasts are often found in the same habitats and share several food-related traits, such as production of high ethanol levels and ability to grow without oxygen. In some food products, like lambic beer, D. bruxellensis can importantly contribute to flavor development. We determined the 13.4 Mb genome sequence of the D. bruxellensis strain Y879 (CBS2499) and deduced the genetic background of several "food-relevant" properties and evolutionary history of this yeast. Surprisingly, we find that this yeast is phylogenetically distant to other food-related yeasts and most related to Pichia (Komagataella) pastoris, which is an aerobic poor ethanol producer. We further show that the D. bruxellensis genome does not contain an excess of lineage specific duplicated genes nor a horizontally transferred URA1 gene, two crucial events that promoted the evolution of the food relevant traits in the S. cerevisiae lineage. However, D. bruxellensis has several independently duplicated ADH and ADH-like genes, which are likely responsible for metabolism of alcohols, including ethanol, and also a range of aromatic compounds.     

PRKAG3 and CAST genetic polymorphisms and quality traits of dry-cured hams - I. Associations in Spanish dry-cured ham Jamón Serrano

The functional single polymorphisms identified in the calpastatin (CAST) gene have been related to the rate of meat tenderization and the protein turnover after slaughter, and the Ile199Val polymorphism identified in the coding region of the protein kinase AMP-activated (PRKAG3) gene has been proven to affect ultimate pH in muscle. The aim of the present study was to show the effects of these genetic polymorphisms on the quality traits of Spanish dry-cured ham Jamón Serrano. A tissue sample from 665 crossbreed pigs were genotyped for PRKAG3 Ile199Val, CAST Arg249Lys and CAST Ser638Arg polymorphisms, and a subsample of 120 dry cured hams was selected to perform physico-chemical, rheological, instrumental colour and sensory analyses. Associations between the polymorphisms and several quality traits of dry-cured ham, mainly related to flavour and texture, were found. The genotypes PRKAG3 Ile/Ile, CAST249 Arg/Arg and CAST638 Arg/Arg, and the haplotype CAST 249Arg-638Arg were the most favourable for Jamón Serrano production.