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Many papers have recently discussed the value of a free sorting method as a rapid and simple alternative to quantitative descriptive analysis, considered the reference tool for food sensorial characterization. The aim of the present paper is to evaluate whether this method of free sorting can also be used to investigate the influence of processing parameters. An experimental design was applied to production conditions of enzymatic hydrolysates from salmon by-products. The effect of four processing parameters (time and temperature of hydrolysis, sugar and antioxidant addition) on the odor of the hydrolysates was studied using a sorting task with 45 untrained panelists and a quantitative descriptive analysis carried out with 11 trained panelists. This study on 21 enzymatic hydrolysates confirms the similarity of the two sensory maps and shows the value of free sorting in the sensory characteristic description step, especially to avoid missing some descriptors. It also highlights in this example that a holistic approach as sorting can reveal more easily than profiling the significant effects of process parameters on sensory characteristics and the relationships between sensory dimensions and instrumental measurements of volatile compounds. Practical Applications Having a rapid and simple method to evaluate the sensory properties of food products and to investigate the effect of processing parameters could be useful during product development steps. Results from the present case study showed that compared with quantitative and descriptive analysis, the holistic approach of sorting task could clearly relate sensory characteristics to processing parameters and seemed efficient for industrial applications and product development. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this study was to assess paralytic phycotoxin uptake in diploid and triploid oysters at two stages of their sexual cycle corresponding to their status in early summer (June) and winter (November). Samples of diploid and triploid oysters were exposed to a toxic culture of Alexandrium minutum for 4 days in each season. No significant differences in filtration or clearance rates were observed during either November or June experiments. When diploid oysters were at resting stage (November), toxin uptake showed no significant difference between the ploidy classes. In contrast, when the diploid oysters were at the peak of their sexual maturation (June), the triploid oysters were seen to accumulate almost double the amount of paralytic toxins as the diploid ones. [Copyright &y& Elsevier]

The aim of this study was to evaluate the importance of biotransformation of paralytic shellfish toxins during the detoxification process in contaminated oysters. Mathematical models based upon the detoxification patterns of digestive gland and other tissues were developed. It was demonstrated that biotransformations do not seem to play an important role in digestive gland or other tissue detoxification kinetics with our data set. Moreover, different toxin transfers from digestive gland toward other tissues were investigated. No significant transfer was highlighted in our data set. These first conclusions were drawn after comparing the results obtained from 13 biotransformations and identifiable transfer scenarios. Finally, to determine a more robust model, all 12 states corresponding to toxic compounds and tissues were aggregated into a single state model. The best adjustment was obtained with a simple one-compartment model based on total flesh toxicity with elimination rate expressed by a function depending on initial concentrations of GTX3 and GTX2 (i.e. the two major toxic compounds found in contaminated oysters). [Copyright &y& Elsevier]

Abstract: The context of this study is the modelling of reactive extrusion process based on an alginate extraction protocol. Residence Time Distribution (RTD) is one important part to predict the kinetics of reactive compounds. A simple model is proposed to predict RTD in fully intermeshing co-rotating twin-screw extruders without reaction. This model, which can be easily extended to reactive case in a future work, is based on the extension of an axial dispersion model, including control parameters (screw speed and flow rate) and geometrical parameters (screw profile and die design). Simulations were performed for various operating and geometrical conditions so as to illustrate possibilities offered by the proposed model. Validation was conducted for two different extrusion applications, seaweed extrusion and polymer extrusion. This highlighted the model ability to predict RTD for various kinds of materials after adjusting only one parameter thanks to a unique experimental RTD curve. [Copyright &y& Elsevier]

The smoking process is a batch one with long du- ration processing (some hours). Deposition of smoke particles can be enhanced by electrostatic precipitation. However, a better knowledge of the fundamental physics is needed to optimize the process. We carried out experimental and numerical studies to obtain essential information on the smoke flow. First, experiments physically characterized the wood smoke. These measures lead us to study the turbulent two-phase flow using an algebraic slip model. The main coupling with electrical forces is taken into account through the slip velocity. Various assumptions were tested concerning the coupled phenomena in order to build an algorithm that is able to simulate these phenomena. Numerical resolutions are compared with data from the literature on a simple electrostatic precipitator (three wires between two plates). Simultaneously, experiments were performed on a simplified scaled-down model of the smoking process (wires and one plate). The results of particle image velocimetry show clearly that the electrostatic precipitation phenomenon is effective above a threshold voltage and is significantly influenced by geometry of electrodes. Experiments and numerical resolutions underwent a validation phase. A small-size industrial demonstrator, of which the promising results will not be discussed in this paper, was conceived by exploiting the presented works. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of five smoking processes on the contents of 10 major phenolic compounds in fillets of herring (Cuplea harengus), namely two traditional processes, involving smoke production by smouldering or friction, one process using liquid smoke atomisation, and two electrostatic smoking processes, also involving smouldering or friction. The effects of several parameters, such as smoking time, smokehouse temperature, electrode voltage, and fish fillet temperature before smoking were assessed for each process. The results indicate that the content of phenolic compounds are strongly affected by the process applied. The percentages of phenolic compounds in fish flesh remained constant and discriminant for a given process, regardless of the parameters studied, which implies that the smoking process used can be identified by determination of phenolic compounds in fish. [Copyright &y& Elsevier]

The aim of this work was to study the effect of adding sugar during proteolysis to promote the Maillard reaction and mask the initial fish odor and off-flavors generated. An experimental design, based on the Doehlert plan, was used to study the influence of hydrolysis conditions (time, temperature, sugar, and antioxidant addition) on the odor characteristics of hydrolysates, soluble protein levels, and amino acid content. Results showed that the lowest level of sugar (10 g of D-xylose added to 1 kg of by-products) was enough to develop a grilled odor in hydrolysates. In the hydrolysis conditions used—i.e., enzyme inactivation at 95°C for 30 min—hydrolysis temperature had no effect on grilled odor production but significantly affected the soluble protein fraction, as did hydrolysis time. Soluble protein content and essential amino acid content increased with the enzymatic reaction but were not modified by adding sugar. Hydrolysis conditions that promote Maillard reactions while keeping a nutritional balance have been identified. [ABSTRACT FROM AUTHOR]

Contamination of shellfish by paralytic shellfish poisoning (PSP) toxins poses an economic threat to shellfish farmers. As contaminated shellfish cannot be harvested for long periods of time, it would be very useful to develop processes to optimise and shorten their detoxification. In this study, Pacific oysters Crassostrea gigas were first experimentally contaminated over a period of 13 days with a continuous flow of toxic Alexandrium minutum cultures at concentrations ranging from 150 to 200 cell ml-1 (toxin content after 13 days of contamination 438 μg STX equiv. 100 g-1 wet weight). Then, two different detoxification treatments were tested and showed detoxification rates greater than those observed in coastal environments. The first treatment consisted of feeding oysters on Skeletonema costatum, at a concentration of 2000 cell m-1 to speed up detoxification rates. The second detoxification method used the same Skeletonema costatum diet, supplemented with silt particles at a concentration of 20 mg L-1. A control was also set up by placing contaminated oysters in seawater with no additional algal food. The detoxification experiment lasted 8 days. Toxin contents were analysed by liquid chromatography with fluorescence detection (LC-FD). The S. costatum diet significantly reduced the time needed for oysters to reach the sanitary threshold (80 μg STX equiv. 100 g-1 wet weight), but no effect of the silt supplement could be demonstrated conclusively. These different detoxification methods did not influence toxin biotransformations as observed in oyster tissues, i.e. epimerisation and decarbamoylation of gonyautoxins 2 and 3. [ABSTRACT FROM AUTHOR]

Ultrasound-assisted enzymatic hydrolysis is a recent process, increasingly employed for plant biomass liquefaction and the recovery of soluble biomolecules. However, to our knowledge, it has never been used on seaweeds, particularly wet ones. The aim of this study was to compare the efficiency of three processes on the liquefaction of the red seaweed Grateloupia turuturu Yamada: enzyme-assisted extraction (EAE), ultrasound-assisted extraction (UAE), and their combination, ultrasound-assisted enzymatic hydrolysis (UAEH). These comparisons will allow the identification as to which process achieves the highest extraction yield of water-soluble compounds. For this purpose, experiments were conducted at 40 °C for 6 h using an enzymatic cocktail of four industrial carbohydrases and an original ultrasonic flow-through reactor. After 6 h, similar profiles were observed between EAE and UAE with the recovery of 71-74 % of the initial material into the soluble phase. However, when these processes were combined, up to 91 % solubilized material was observed in the same time, with a synergistic effect after 2 h. From a biochemical point of view, UAEH improved the extraction of nitrogen and carbon compounds and, more precisely, carbohydrates and amino acids. This study demonstrates that ultrasound improved the enzymatic hydrolysis, probably by an increase in the mass transfer and a disruption of the thallus due to the implosion of the cavitation bubbles generated. UAEH is clearly an efficient procedure for the liquefaction of wet seaweeds, enabling the recovery of valuable components. [ABSTRACT FROM AUTHOR]

Abstract: The maximum specific growth rate (μ max) of Brochothrix thermosphacta, a spoilage bacteria of cooked peeled shrimp, and Lactococcus piscium CNCM I-4031, a bioprotective strain, was investigated under different conditions of temperature, NaCl concentrations and pH. The basic modelling approach used was the Gamma concept (γ-concept) and the model developed was then adapted to shrimp. Cardinal growth parameters were quite similar for the two strains, except for NaCl. No NaCl was required for growth and the NaClmax was three-times higher for B. thermosphacta than for L. piscium (62 and 23 g l−1 respectively). However, tolerance to NaCl was higher in seafood than in liquid broth, possibly due to presence of osmoltically active molecules. L. piscium and B. thermosphacta were psychrotolerant, with T min = −4.8 and −3.4 °C, T opt = 23.4 and 27.0 °C and T max = 27.2 and 30.8 °C respectively. The optimal pH was neutral and growth possible till pH = 4.8 for the two strains, assuming possible applications of the bioprotective strain in lightly marinated seafood. The μ max of B. thermosphacta in shrimp was a little higher than in L. piscium whatever the environmental conditions. Validation of the model showed that the γ-concept was suitable for predicting μ max of B. thermosphacta in shrimp. Data generated in this study can be used to adapt the model to other foods with few additional experiments and the effect of different parameters may be added in the future. The model was less accurate for the bioprotective strain and the effect of NaCl must be studied in more detail directly in the matrix. [Copyright &y& Elsevier]

Alginates are natural polysaccharides that are extracted from brown seaweeds and widely used for their rheological properties. The main step in the extraction protocol used in the alginate industry is that of alkaline extraction. A batch process is used for this step, which is time-, water-, and reactant-consuming. The possibility of extracting by reactive extrusion was investigated. The reactive extrusion process appeared to be more efficient than the batch process for the alkaline extraction of alginates from Laminaria digitata in several key ways: Time demand is reduced from about an hour to only few minutes, water and reactant requirements are divided by more than a factor 2, extraction yield is 15% higher (relative enhancement), and the rheological properties of the product were all enhanced. Hence, reactive extrusion could be an interesting alternative process for the alginate industry to produce high rheological properties alginates. [ABSTRACT FROM AUTHOR]

The occurrence of new phytoplankton species in a coastal area may be explained by the import of shellfish containing whole live algal cells in their digestive tracts. Indeed, shellfish containing toxic algal cells can induce both primary contaminations in safe areas (initially free from toxic microalgae), and secondary contaminations of other shellfish growing in the same area via the faeces of the imported animals. To mitigate this problem, shellfish need to be placed in a separate holding tank and their intestinal content purged. For a deeper understanding of the risks associated with transferring contaminated shellfish, oysters (Crassostrea gigas) and mussels (Mytilus edulis) were purposely fed either Alexandrium minutum or A. catenella (Dinophyceae) or Pseudo-nitzschia calliantha (Bacillariophyceae) toxic algae for 2 h. They were then transferred into individual tanks where they were continuously fed with a non-toxic alga, Tetraselmis suecica. Biodeposit production, faeces composition, and filtration rates were monitored for the shellfish over a 6-h period. The effect of temperature differences and different initial toxic algae concentrations were compared. This study revealed a relationship between temperature and cell lysis in the oyster digestive tract. It also indicated that toxic algae concentration did not seem to influence gut passage time in oysters, while a significant effect was observed in mussels, and confirmed the existence of a difference between oyster and mussel feeding patterns. [ABSTRACT FROM AUTHOR]

Abstract: The relationship between smoking parameters and odour characteristics, evaluated by a trained sensory panel, were studied on smoked herring. In addition, a possible correlation between the content of 10 phenolic compounds and sensory perceptions was investigated. Five smoking techniques were applied, combining smoke production conditions, performed by pyrolysis of beech wood sawdust or by friction of beech wood log, with smoke deposition, either in a controlled kiln (traditional smoking) or by an electrostatic process. In the fifth smoking technique, a purified condensate of beech smokes was vaporised on fish fillets in the smokehouse. The time of smoking was 3h for traditional smoking and the liquid smoke atomisation process and 12min for the electrostatic method. The effects of three smoking temperatures (16, 24, 32°C) were tested for both the traditional and the liquid smoke atomisation processes, as well as the effect of the position of the exhaust valve in the smokehouse in the case of the traditional method. Two different voltages were applied for the electrostatic process, 37 and 42kV. The results show a clear discrimination of the products since some odour characteristics are specifically related to the smoking process applied. All the studied parameters (smoke generation, deposition of smoked compounds, smoking temperature, exhaust valve opening in the smokehouse or voltage applied in the electrostatic tunnel) have an effect on the smell characteristics of smoke products, either on the odour intensity and/or on the kind of smoke note. Multiple linear models were tested to find relationships between sensory properties and phenolic compounds. Although some compounds seem to be mainly involved in the “cold ash” note, the results illustrate the difficulty of reaching clear conclusions about a correlation between smoke odour and only 10 phenolic compounds. It is suggested that a better model could be found if other volatile compounds, besides the phenolic class, are taken into account. [Copyright &y& Elsevier]

Alginates are natural polysaccharides that are extracted from brown seaweeds and widely used for their rheological properties. The central step in the extraction protocol used in the alginate industry is the alkaline extraction, which requires several hours. In this study, a significant decrease in alginate dynamic viscosity was observed after 2 h of alkaline treatment. Intrinsic viscosity and average molecular weight of alginates from alkaline extractions 1–4 h in duration were determined, indicating depolymerization of alginates: average molecular weight decreased significantly during the extraction, falling by a factor of 5 between 1 and 4 h of extraction. These results suggested that reducing extraction time could enable preserving the rheological properties of the extracted alginates. [ABSTRACT FROM AUTHOR]