Detection of Biological CO<Subscript>2</Subscript> and 1,3-Pentadiene Using Non-refrigerated Low-Cost MWIR Detectors

The early detection of spoiling metabolic products in contaminated food is a very important tool to control quality. Some volatile compounds produce unpleasant odours at very low concentrations, making their early detection very challenging. This is the case of 1,3-pentadiene produced by microorganisms through decarboxylation of the preservative sorbate. In this work, we have developed a methodology to use the data produced by a low-cost, compact MWIR (Mid-Wave IR) spectrometry device without moving parts, which is based on a linear array of 128 elements of VPD PbSe coupled to a linear variable filter (LVF) working in the spectral range between 3 and 4.6 μm. This device is able to analyze food headspace gases through dedicated sample presentation setup. This methodology enables the detection of CO₂ and the volatile compound 1,3-pentadiene, as compared to synthetic patrons. Data analysis is based on an automated multidimensional dynamic processing of the MWIR spectra. Principal component and discriminant analysis allow segregating between four yeast strains including producers and no producers. The segregation power is accounted as a measure of the discrimination quality.     

Antimicrobial‐releasing films and coatings for food packaging based on carvacrol and ethylene copolymers

Efficiency in antimicrobial packages based on the release of active agents depends on their retention into the packaging materials and on the extent and rate of their release to the package headspace. In this work, the effects of polymer chemical composition and matrix morphology on the release of carvacrol were explored. Films and coatings containing carvacrol, and manufactured from four polyolefin latexes of a range of polarities (ethylene–octene (LLDPE) < ethylene–vinyl acetate (EVA) < < ethylene–methacrylic acid (EMA) ≈ ethylene–alkaline methacrylate (ION)), were characterized in terms of their active and functional properties. Scanning electron microscopy images evidenced that films presented heterogeneous structures caused by an incomplete coalescence of their polymeric particles. Consequently, different film structures of decreasing heterogeneity, porosity and roughness (LLDPE > EVA > > ION > EMA) were obtained, exhibiting morphologies generally correlated with the melting temperatures and active behaviours of the polymers. LLDPE and EVA, the most heterogeneous polymers, were generally more permeable, less resistant, more deformable, less transparent and more wettable than EMA and ION, of coalesced structure. For carvacrol, LLDPE and EVA yielded higher values of the diffusion coefficient, in agreement with their permeability results, whereas EMA and ION showed higher solubilities, according to their greater affinity for the active molecule, as derived from their ionic nature. The evolution of the release of carvacrol from the studied films was experimentally measured and theoretically predicted through determination of its solubility and diffusivity parameters. Excellent agreement between both experimental and predicted data was finally observed. © 2015 Society of Chemical Industry     

Assessment of acrylamide intake of Spanish boys aged 11–14 years consuming a traditional and balanced diet

Acrylamide is a toxic and potentially cancer causing chemical formed in thermally treated foods, especially in carbohydrate rich. New dietary habits acquired by adolescents, increasing snacking and fast food consumption, lead to a high acrylamide intake, since the composition of these meals and their processing promote its appearance. This study investigated acrylamide daily exposure in a group of Spanish male adolescents (11–14 years) consuming a balanced diet based on their food preferences but reducing snacking and fast food, aimed to determine whether acrylamide exposure was reduced by the consumption of a traditional diet. Acrylamide content of main dishes was analyzed and input per serving calculated. The Spanish potato omelette and the grilled loin of pork with fried potatoes presented the highest levels of acrylamide (128 and 111 μg/kg respectively), followed by different meals also containing potatoes or cereal derived products. The acrylamide total intake was estimated at 0.534 μg/kg body weight/day, where the highest percentage was provided by the breakfast (31.66%), the afternoon snack being the lowest contributor (16.19%). These results indicate consumption of a balanced and traditional diet, besides the well known beneficial effects on health, can also moderate acrylamide exposure and thus its possible long-term toxicological effect.     

Hygienic quality of ewes' milk cheeses manufactured with artisan-produced lamb rennet pastes

The use of artisan-produced lamb rennet pastes, but not any of the other commercial animal rennets, imparts a characteristic flavour to the cheese, so most Mediterranean ewes' milk cheeses are coagulated with this kind of rennet paste. In contrast to the advantages of using lamb or kid rennet pastes from the sensory point of view, questions are still raised as to their hygienic quality. The goal was to examine the microbiological and enzymic quality of lamb rennet pastes prepared by cheese manufacturers for their own use, and evaluate the hygienic quality of raw sheeps' milk cheeses made with them, using Idiazabal cheese as a model. Lamb rennet pastes prepared by artisan cheese makers from the Basque region of Spain (27), and Italy (8) were evaluated. For cheese making experiments 5 different lamb rennet pastes were selected among the 27 samples from the Basque Country region of Spain. Microbiological analyses were carried out on samples from rennet pastes, rennet extracts, milks and cheeses during ripening. Enzymic activities studied in rennet paste were: total coagulating strength and lipase. Analysis of variance and Student's t-tests was performed. The results show that the artisan-produced rennet pastes contain high levels of a variety of microorganisms. After 60 ripening days, which is the minimum ripening period required for Idiazabal cheese prior to its commercialization, no Eschericia coli, Clostridium, Salmonella spp. or Listeria monocytogenes were detected, and levels for the rest of the microorganisms were below the limits of the European legislative standards for cheese manufactured with raw milk. We can conclude that the use of artisan-produced lamb rennet pastes of questionable hygienic quality for the manufacture of raw milk hard cheeses yields products of good hygienic quality.     

Proteolysis,Texture, and Sensory Characteristics of Serrano Hams from Duroc and Large White Pigs during Dry‐Curing

Proteolysis, texture, physicochemical, and sensory characteristics of Serrano hams from Duroc and Large White pigs at 5, 7, 9, 12, and 15 m of curing (3 hams per breed per curing time) were investigated. Higher concentrations of some sarcoplasmic and myofibrillar proteins, peptides with molecular mass in the ranges 3700 to 12000 Da, 700 to 2000 Da, and below 450 Da, and total free amino acids were recorded for Large White hams, while hydrophobic peptides were at higher levels in Duroc hams. A 40 kDa peak in the low‐ionic‐strength soluble protein fraction and 2 peaks of 40 and 45 kDa in the high‐ionic‐strength soluble protein fraction found only in Duroc hams could be of use in discriminating products from different breeds. Physicochemical and textural characteristics of both types of hams evolved similarly during curing and differences in organoleptic traits between breeds were negligible. Flavor intensity and flavor quality of hams were strongly correlated to curing time, with r² values over 0.95 for flavor intensity and over 0.90 for flavor quality, and to the concentration of total free amino acids, with r² values over 0.90 for both flavor intensity and flavor quality. The sensory evaluation scores of Duroc hams, at least as high as those of Large White hams, make the production of high‐quality Serrano ham from pure breed Duroc pigs feasible. Practical Application: Duroc breed crosses are advantageous in the production of dry‐cured hams, resulting in higher marbling, enhanced flavor and lower processing losses, but the characteristics of pure breed Duroc hams have not been investigated. The similar evolution of the compositional, proteolytic, textural, and sensory characteristics of Serrano hams from Duroc and Large White pigs during dry‐curing recorded in the present work makes the production of high‐quality dry‐cured hams from pure breed Duroc pigs feasible. Three protein peaks found only in Duroc hams can be of use to discriminate products from different breeds.     

Effects of hydrocolloids and high-pressure-heating processing on minced fish gels

Multivariate statistical methods were applied to data sets of measured gelling properties of blue whiting mince with several hydrocolloids added (locust bean gum, guar gum, xanthan gum, carboxymethylcellulose, 1-carrageenan, 3-carrageenan or alginate) induced under different pressure-time-temperature gelling conditions. The main differences between gels were attributed to the process; all the gels were classified in three clusters on the basis of gelling treatment: (1) high-pressure at moderate heating, (2) high-pressure at cold temperature and (3) heating at atmospheric pressure. Cluster 1 was characterized by very elastic, light gels with high water holding capacity. In cluster 2, gels presented high puncture test properties (breaking deformation, breaking force, work of penetration) and high cohesiveness and water holding capacity. Cluster 3 gels presented low penetration test properties and cohesiveness; high adhesiveness and hardness; high lightness and yellowness. Each cluster was subdivided to describe the gel properties between the hydrocolloid groups, attributing the differences mainly to yellowness (b*), breaking deformation, breaking force and work of penetration.     

Characterisation of onion (Allium cepa L.) by-products as food ingredients with antioxidant and antibrowning properties

Processing and stabilising onion wastes (residues and surpluses of onion) could solve the environmental problem derived from a great onion wastes disposal. Moreover, obtaining stabilised onion by-products as natural antioxidant food ingredients could be advantageous to food industry, not only to improve the use of onion wastes but also to obtain new natural and functional ingredients. The aim of this study was to characterise onion by-products – juice, paste and bagasse – from two Spanish onion cultivars – ‘Figueres’ and ‘Recas’ – that have been stabilised by thermal treatments – freezing, pasteurisation and sterilisation – in order to evaluate the effect of the processing and stabilisation treatment on the bioactive composition, antioxidant activity and polyphenol oxidase (PPO) enzyme inhibition capacity. The results obtained triggered to choose one onion by-product offering better characteristics for its potential development as a food ingredient: source of antioxidant and antibrowning bioactive compounds. In this study it was shown that processing of ‘Recas’ onion wastes to obtain a paste (mixture content) and applying a mild pasteurisation were the best alternatives to obtain an interesting stabilised onion by-product with good antioxidant properties that made useful its use as functional food ingredient.     

Proximate composition and extraction of carotenoids and lipids from Brazilian redspotted shrimp waste (Farfantepenaeus paulensis)

The chemical composition of redspotted shrimp (Penaeus paulensis) waste was investigated. The shrimp waste (freeze-dried heads, shells and tails) was found to have high protein (49% d.w.) and ash (27% d.w.) contents, but a low lipid content (4.9% d.w.) although the latter was higher than those found in other kinds of shrimp captured in Brazil. The fatty acid compositions showed that the lipids had a high content of unsaturated fatty acids, mainly EPA (C20:5; n-3) and DHA (C22:6; n-3). In order to establish an efficient and environmentally friendly recovery process for the astaxanthin (principal carotenoid and antioxidant present in the waste), the following processes were examined: traditional solvent extraction (TSE), super-critical fluid extraction (SC-CO₂) and super-critical fluid extraction with co-solvent (SC-CO₂ + ethanol). The temperature and pressure conditions for all the SC-CO₂ extractions were 50 °C and 30.0 MPa. The results showed that the mixture of 60% (v/v) n-hexane:isopropyl alcohol gave the highest (53 mg/kg waste) carotenoid extraction yield as compared to acetone, SC-CO₂ and SC-CO₂ + ethanol. The SC-CO₂ showed the lowest extraction yield of astaxanthin, but the addition of the entrainer (10% w/w) produced an important effect, increasing the astaxanthin extraction to values of 57.9%, similar to extraction with acetone (63.3%).     

Effects of high pressure and mild heat on endogenous microflora and on the inactivation and sublethal injury of Escherichia coli inoculated into fruit juices and vegetable soup

The objective of this study was to determine the effects of high-pressure treatments and mild temperatures on endogenous microflora and Escherichia coli CECT 515 artificially inoculated into orange and apple juices and vegetable soup. In general, the viability of aerobic bacteria was significantly reduced as pressure and temperature increased. Although the greatest reduction in the concentration of aerobic mesophilic vegetative cells was reached at 350 MPa and 60 degrees C, the same reduction occurred in fruit juices at 350 MPa and 20 degrees C. Yeasts and molds were below the level of detection (1 log CFU/ml) for the fruit juices and did not exceed 2 log CFU/ml for vegetable soup. Foods inoculated with E. coli were subjected to several treatments as indicated by the mathematical model applied in response surface methodology to obtain the maximum information with the minimum number of experiments. The number of tests for a range of pressures (150 to 350 MPa) and temperatures (20 to 60 degrees C) was limited to 11. The models were considered adequate because of satisfactory R2 values. The optimum process parameters (pressure and temperature) for a 6-log reduction of E. coli were obtained at 248.25 MPa and 59.91 degrees C in orange juice, 203.50 MPa and 57.18 degrees C in apple juice, and 269.8 MPa and 59.9 degrees C in vegetable soup. Sublethal injury of E. coli occurred as pressure and temperature increased. Nearly all of the E. coli cells were injured at 350 MPa and 20 degrees C in fruit juices and after all treatments in vegetable soup.     

Current Applications and Future Trends of Lactic Acid Bacteria and their Bacteriocins for the Biopreservation of Aquatic Food Products

This review emphasizes the importance of novel biopreservation strategies and their application to ensure seafood quality and safety especially within the context of increasing demand for minimally processed aquatic food products. The paper addresses the major hazards linked to spoilage and pathogenic bacteria found in fresh and processed aquatic foods, mainly ready-to-eat seafood subjected to short-term storage, and the biological strategies that can be used to minimize their growth. This is followed by an overview of current knowledge about the inhibiting bacteriocin-producing lactic acid bacteria isolated from aquatic food products or that is being evaluated for ensuring safety on seafood and seafood products as well as the characteristics of their bacteriocins. The different strategies for the biopreservation of aquatic food products, such as protective cultures or spray drying, and their current and future applications for the preservation of seafood products are also explored. Finally, novel antimicrobial active and intelligent packaging strategies based on antimicrobials film allowing controlled release of bacteriocins to refrigerated aquatic food products are also discussed.