Advances in quantification and analysis of the celiac-related immunogenic potential of gluten

Gluten-free products have emerged in response to the increasing prevalence of gluten-related disorders, namely celiac disease. Therefore, the quantification of gluten in products intended for consumption by individuals who may suffer from these pathologies must be accurate and reproducible, in a way that allows their proper labeling and protects the health of consumers. Immunochemical methods have been the methods of choice for quantifying gluten, and several kits are commercially available. Nevertheless, they still face problems such as the initial extraction of gluten in complex matrices or the use of a standardized reference material to validate the results. Lately, other methodologies relying mostly on mass spectrometry-based techniques have been explored, and that may allow, in addition to quantitative analysis, the characterizationof gluten proteins. On the other hand, although the level of 20 mg/kg of gluten detected by these methods is sufficient for a product to be considered gluten-free, its immunogenic potential for celiac patients has not been clinically validated. In this sense, in vitro and in vivo models, such as the organoid technology applied in gut-on-chip devices and the transgenic humanized mouse models, respectively, are being developed for investigating both the gluten-induced pathogenesis and the treatment of celiac disease. Due to the ubiquitous nature of gluten in the food industry, as well as the increased prevalence of gluten-related disorders, here we intend to summarize the available methods for gluten quantification in food matrices and for the evaluation of its immunogenic potential concerning the development of novel therapies for celiac disease to highlight active research and discuss knowledge gaps and current challenges in this field.     

Effects of nisin concentration on properties of gelatin film-forming solutions and their films

The addition of nisin into a gelatin matrix can change properties of the film. The aim of this work was to develop gelatin-based films containing different nisin concentrations in order to study their influence on the film's antimicrobial and physical properties and their rheological properties as a film-forming solution (FFS). The FFS was characterised by rheological assays, and the gelatin-based active films were characterised and assessed by the effects of nisin concentrations on their various properties, including antimicrobial activity. Nisin's concentration affected not only its viscoelastic properties of FFS but also its film solubility in water, film surface roughness and light barrier. The addition of nisin also slightly modified the water contact angle and the mechanical properties of the gelatin films. Finally, the films demonstrated activity against Staphylococcus aureus and Listeria monocytogenes at concentrations above 56 mg of nisin g⁻¹ of gelatin.     

Detection of methicillin-resistant coagulase-negative staphylococci and PVL/mecA genes in cefoxitin-susceptible Staphylococcus aureus (t044/ST80) from unpasteurized milk sold in stores in Djelfa,Algeria

This study was designed to determine antimicrobial resistance phenotypes and genotypes and virulence factors in Staphylococcus aureus and coagulase-negative staphylococci (CNS) in unpasteurized milk sold in Djelfa, Algeria. Eighty-two unpasteurized cow milk samples were randomly obtained from 82 retail stores in Djelfa and tested to detect staphylococci. Species were identified by biochemical tests and MALDI-TOF. Antimicrobial resistance phenotypes and genotypes were determined by disk diffusion test, PCR, and sequencing. The Staph. aureus isolates were subjected to spa typing, multilocus sequence typing, and detection of virulence genes and the scn gene by PCR and sequencing. Forty-five (54.9%) milk samples were contaminated by staphylococci and 45 isolates were recovered: 10 Staph. aureus (12.2% of total samples) and 35 CNS (42.7%). Resistance to penicillin (blaZ), tetracycline (tetL/tetK), and erythromycin (ermB/msrA/ermC) were the most common phenotypes (genotypes). Three CNS were methicillin-resistant and all were mecA-positive. The Staph. aureus isolates were ascribed to the following lineages [spa type/sequence type/associated clonal complex (number of isolates)]: t267/ST479/CC479 (n = 6), t1510/ST5651/CC45 (n = 1), t359/ST97/CC97/ (n = 1), t346/ST15/CC15 (n = 1), and t044/ST80 (n = 1). The mecA gene was detected in the cefoxitin-susceptible t044/ST80 isolate and co-harbored the lukF/lukS-PV and scn genes. The detection of mecA-PVL-positive Staph. aureus, methicillin-resistant CNS, and multidrug-resistant staphylococcal species indicates a potentially serious health issue and reveals that unpasteurized milk sold in Djelfa city could be a potential vehicle for pathogenic and antimicrobial-resistant staphylococci.     

Isoflavone determination in spontaneous legumes identified by DNA barcodes

Isoflavones have been associated with several health protective effects. In this work spontaneous legume plants were screened as putative sources of dietary isoflavones. A molecular identification of the collected species was performed throughout DNA barcoding using ITS, rbcL, rpoC1 and matK sequences. The use of a multi-locus barcoding system complemented with basic morphological information allowed the unequivocal identification at the species level of 90% of the samples. The determination of isoflavone content was performed by high-performance liquid chromatography with diode-array detection. Total average contents in the studied species were significantly different, Ononis natrix and Cytisus scoparius possessing the highest total isoflavones content (396 and 273 mg kg⁻¹, respectively) and Lotus creticus, the lowest (20 mg kg⁻¹). The correlation of total isoflavone content with the phylogeny of this set of plants as determined by the rpoC1 sequences was evaluated for the first time.     

Mineral profile of “fino” wines using inductively coupled plasma optical emission spectrometry methods

Fifty wines from the Denomination of origin (DO) of Condado de Huelva were analysed for mineral content by measuring 12 elements (Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, P, Sr and Zn) using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). Samples were previously digested by heating with H₂O₂/HNO₃ mixture. The results obtained showed that metal data set were non-normally distributed and accordingly, non-parametric statistics were applied. The average levels (medians) of these elements found in the samples are as follows, in mg/L: 2.54 (Al); 0.06 (Ba); 82.58 (Ca); 0.21 (Cu); 3.53 (Fe); 865.34 (K); 68.87 (Mg); 0.71 (Mn); 32.77 (Na); 71.61 (P); 0.48 (Sr); 0.56 (Zn). The interrelation of metal couples was studied through the Spearman non-parametric sample correlation, being Fe/Al, P/Mg, and Zn/Ba the most important correlations established. As a result of this study, we can suggest that the contribution to the safety intake limits (per week) of the studied elements through the wine consumption is not significant. Actually, they range between 0.1% in Fe and 11.9% in Mg, for normal drinkers.     

Critical assessment of methods for measurement of temperature profiles and heat load history in microwave heating processes—A review

Limitations of microwave processing due to inhomogeneities of power input and energy absorption have been widely described. Over- and underheated product areas influence reproducibility, product quality, and possibly safety. Although a broad range of methods is available for temperature measurement and evaluation of time/temperature effects, none of them is sufficiently able to detect temperature differences and thermally induced effects within the product caused by inhomogeneous heating. The purpose of this review is to critically assess different methods of temperature measurement for their suitability for different microwave applications, namely metallic temperature sensors, thermal imaging, pyrometer measurement, fiber optic sensors, microwave radiometry, magnetic resonance imaging, liquid crystal thermography, thermal paper, and biological and chemical time-temperature indicators. These methods are evaluated according to their advantages and limitations, method characteristics, and potential interference with the electric field. Special attention is given to spatial resolution, accuracy, handling, and purpose of measurement, that is, development work or online production control. Differences of methods and examples of practical application and failure in microwave-assisted food processing are discussed with a special focus on microwave pasteurization and microwave-assisted drying. Based on this assessment, it is suggested that infrared cameras for measuring temperature distribution at the product surface and partially inside the product in combination with a chemical time/temperature indicator (e.g., Maillard reaction, generating heat-induced color variations, depending on local energy absorption) appear to be the most appropriate system for future practical application in microwave food process control, microwave system development, and product design. Reliable detection of inhomogeneous heating is a prerequisite to counteracte inhomogeneity by a targeted adjustment of process and product parameters in microwave applications.     

Encapsulation of protein hydrolysates by spray drying: feasibility of using buffalo whey proteins

This work aimed to produce and encapsulate protein hydrolysates of buffalo origin using spray drying with gum arabic and maltodextrin as encapsulating agents. The following core ratios were applied: encapsulating agent in the ratios of 1:10 and 1:15, with 50% gum arabic and 50% maltodextrin (50:50), and 70% gum arabic and 30% maltodextrin (70:30). The encapsulated particles were between 2.0 and 20.0 μm. The encapsulation efficiency of the samples was above 95% at the initial time. After 45 days of storage, encapsulation efficiency decreased to values below 60%. The 70:30 samples showed a significant decrease (P < 0.05) in hygroscopicity, moisture and water activity compared with free hydrolysates. The encapsulation process increased the values of oil retention, emulsifying activity and solubility of whey protein hydrolysates for all proportions evaluated, both at the initial time and after 45 days of storage. The branched-chain amino acid concentration was higher in samples encapsulated at the 1:10 ratio. The spray drying encapsulation of buffalo protein hydrolysates with suitable encapsulating agents improves the techno-functional characteristics of these hydrolysates, hence expanding their use in different food matrices and enabling the use of buffalo cheese whey.     

Rheological Aspects of Spanish Honeys

The purpose of this work was to investigate the rheological behavior of Spanish honeys under different conditions (at different temperatures and concentrations). All the samples were characterized to determine their physicochemical (moisture, ⁰Brix, pH, ash, conductivity, color, total acidity, diastase activity, 5-hydroxymethylfurfural content, sugar content) and thermal (glass transition temperature) profiles. The honeys samples (80.4–82 ⁰Brix) behaved as Newtonian fluid; as expected, their viscosity increased with the solid content and decreased with the temperature. Two experimental viscosity models (Arrhenius and Vogel–Taumman–Fulcher) were checked using the experimental data to correlate the influence of temperature on honey viscosity. A simplified model was proposed to describe the combined effect of the temperatures and concentrations (⁰Brix) on the viscosity of Spanish honeys. The dynamic viscosity and complex viscosity had the same magnitude at 40 °C, 45 °C, and 50 °C for of all the samples and the Cox Merz rule could be applied at these temperatures.     

Gelled vegetable desserts containing pea protein, κ-carrageenan and starch

Due to recent animal diseases, cholesterol intake worries and strong demand for healthy food, there is a greater pressure for the direct consumption of vegetable proteins in food products. In this work, the objective is to develop alternative of strictly vegetable origin desserts based on gelled systems with required physical structure and perceived texture. For this reason, it is important to control the properties of the biopolymer mixtures and understand the phase separation behaviour under different physicochemical conditions. The firmness and storage modulus of different formulations of pea protein/κ-carrageenan/starch systems processed and cooled at different conditions are compared with those parameters obtained for commercial products. Formulation and thermal conditions were determined to influence the texture and storage modulus of the mixed systems. Confocal microscopic images showed that phase separation between pea protein and κ-carrageenan takes place, leading to the formation of two network systems. The binding of water effect, of the starch swollen granules, promotes the concentration of pea protein and κ-carrageenan, reinforcing the gel structure.