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Aims: The present study aims to evaluate the phytochemical and pharmacological c of the optimized Citrus sinensis ‘Maltese half-blood’ essential oils peels (CsEO) extraction yields using Response-Surface Methodology (RSM). Background: Citrus fruits have been a valuable economic crop for thousands of years. Furthermore, citrus essential oils are significant in the perfume, food, and beverage sectors, as well as aromatherapy and medical medicines. Objective: There have been few investigations on Citrus sinensis ‘Maltese half-blood’ essential oil. Methods: Citrus sinensis ‘Maltese half-blood’ essential oil peels (CsEO) extraction yields were performed by hydro-distillation and optimized by using Response-Surface Methodology (RSM). The oils were analysed by GC-MS. Different chemical tests were used to evaluate antioxidant activities. The healing potential was evaluated using models’ wounds on Wistar rats. Results: The RSM optimization demonstrated the highest yield of CsEO of 6.89 g/100 g d.b. All three tested factors significantly influenced the CsEO extraction yield: washing saline solution concentration, washings number, and drying percentage of peels. Significant antioxidant activities were noted in CsEO: the DPPH assay reported an IC50 of 0.225 ±0.014 mL/mg, the FRAP assay showed an IC50 of 0.235 ±0.001, and the NO assay was an IC50 in order of 0.259 ±0.019. CsEO was not genotoxic and considerably decreased the levels of DNA lesions induced by oxidants. Also, applying a cream with CsEO on wounds promotes significantly rapid wound healing. Conclusion: CsEO could be considered a rich natural source of antioxidants and bio-compounds to accelerate wound healing. It can be used in pharmaceutical sectors as an alternative to synthetic chemicals.

The oleic industry is one of the most polluting in food industry sector. Among other harmful by-products, it generates charged sludge. Coagulation–flocculation is a relatively simple physico–chemical technique that ensures excellent separation of solid particles from dissolved ones. To obtain acceptable treated water quality, this method is used along with TiO2-based sunlight photo-catalysis. We optimize this binary process to treat mill wastewater collected from the region of Mahdia, east center of Tunisia, by applying a combination of mixture design (3 components-mixture: lime water, iron solution and cactus mash) and full factorial design 22 (2 process factors: dilution ratio (aqueous solution/water) and used TiO2 mass). Both the phenolic compounds removal and solution decolorization are closely monitored. The quadratic models for those two responses indicate optimum conditions to a coagulation-flocculation performance using a mixture of 48.48% of lime water with 51.52% of cactus mash with low level of dilution rate and high level of TiO2 mass. Experience of those conditions validated calculi, and they give a decolorization of 92.57 ± 0.90% and an organic degradation of 96.19 ± 0.97% in good concordance with the mathematic predictions that yield 93.06% of decolorization and 98.70% of organic degradation.

Using the statistical approach, this work seeks to optimize the process parameters to boost the generation of an organic solvent-tolerant lipase by Staphylococcus capitis SH6. The main parameters influencing the enzyme production were identified by using Plackett-Burman's screening design. Among the test variables, only tryptone (25 g/L), malt extract (2.5 g/L), NaCl (10 g/L) and pH (7.0) contributed positively to enzyme production. Then, the crude lipase was immobilized by adsorption on CaCO3 at pH 10. A maximum immobilization efficiency of 82% was obtained by incubating 280 mg of enzyme with CaCO3 (1 g) during 30 min. The immobilized lipase was more stable toward organic solvents than the free enzyme. It retained about 90% of its original activity in the presence of ethanol and methanol. After that, the immobilized enzyme was used for biodiesel production by transesterification process between waste oil and methanol or ethanol during 24 h at 30 °C. Our results show that the lipase can be utilized efficiently in biodiesel industry. Likewise, we have demonstrated that the immobilized enzyme may be implicated in the biodegradability of waste grease; the maximum conversion yield into fatty acids obtained after 12 h at 30 °C, was 57%.

In the current investigation, the capacity of different yeast strains to decolorize reactive black 5 (RB-5) was assessed. A comparative study between the different strains demonstrated that Saccharomyces cerevisiae X19G2 exhibited the highest decolorization rate (69.20 ± 1.16%) after 48 h of incubation. This strain was selected to optimize the medium components’ concentrations for maximum RB-5 decolorization. Response-surface methodology (RSM) was tested for the most significant parameters (glucose, yeast extract and RB-5 dye concentrations) that were previously determined by Plackett–Burman design. A dye decolorization rate of 99.59 ± 0.24% was achieved within 48 h using a maximum RB-5 concentration (0.15 g/L) with glucose and yeast extract concentrations equalling to 10.5 g/L and 1 g/L, respectively. Experimental data results proved to fit well with the pseudo-second order kinetics model. The phytotoxicity assessment was carried out using Raphanus sativus seeds to determine the toxicity of RB-5 before and after treatment by S. cerevisiae. Results suggested that germination rate and the length of seeds radical irrigated with 0.15 g/L of RB-5 decreased by 30 and 53%, compared to those irrigated with treated solution. Therefore, metabolites derived from decolorization of RB-5 by S. cerevisiae X19G2 were significantly less toxic than the original dye.

The effect of heavy metals presence on the decolourization of Reactive Black 5 by Pseudomonas aeruginosa was evaluated.In the current study, a newly isolated strain identified as P. aeruginosa strain Gb 30 was selected for its ability to remove high concentration of Reactive Black 5 and resistance to several heavy metals (CuIn this study, we showed that P. aeruginosa strain Gb30 could be used for dye removal even at high concentrations of heavy metals. The developed models could provide basic information that may help for the best management of the bacteria-mediated decolourization process at the industrial scale.This study opens new directions for the management of textile industry wastewaters containing dyes and heavy metals using bioaugmentation by P. aeruginosa strain Gb30.

Fermentation process waste was used as an ideal alternative, with low cost and high efficiency, to the expensive methods of removing dyes from wastewater. In this study, granular particles of heat treated-lyophilized biomass of the fungi Neonectria radicicola were tested to remove the three acid dyes Acid Orange 51 (AO 51), Reactive Red 75 (RR 75) and Direct Blue 86 (DB 86) from aqueous solutions and their adsorption was characterized in terms of adsorption isotherms and kinetics. Biosorption was investigated under different conditions of pH, contact time, temperature, adsorbent dosage and dye concentrations. The obtained results showed that optimum pH for dye adsorption was 2.0, the maximum uptake between 30 and 60 min of contact time and the equilibrium was reached within 60 min. The adsorption kinetics of the three dyes followed a pseudo-first-order rate model and Redlich–Peterson model fitted well the adsorption isotherms. The maximum adsorption capacities determined from the Redlich–Peterson equation were 120.6, 75.37 and 200.5 L g−1 for AO 51, RR 75 and DB 86, respectively. FT-IR analysis indicates the involvement of various functional groups and SEM images showed morphological changes.

Proteases are industrially important catalysts. They belong to a complex family of enzymes that perform highly focused proteolysis functions. Given their potential use, there has been renewed interest in the discovery of proteases with novel properties and a constant thrust to optimize the enzyme production. In the present study, a novel extracellular neutral protease produced from Arthrospira platensis was detected and characterized. Its proteolytic activity was strongly activated by β-mercaptoethanol, 5,5-dithio-bis-(2-nitrobenzoic acid) and highly inhibited by Hg2+ and Zn2+ metal ions which support the fact that the studied protease belongs to the cysteine protease family. Using statistical modelling methodology, the logistic model has been selected to predict A. platensis growth-kinetic values. The optimal culture conditions for neutral protease production were found using Box-Behnken Design. The maximum experimental protease activities (159.79 U/mL) was achieved after 13 days of culture in an optimized Zarrouk medium containing 0.625 g/L NaCl, 0.625 g/L K2HPO4 and set on 9.5 initial pH. The extracellular protease of A. platensis can easily be used in the food industry for its important activity at neutral pH and its low production cost since it is a valuation of the residual culture medium after biomass recovery.

Background Salvia officinalis L. essential oil (SoEO) was mostly traditionally used to medicate various diseases as cancer. Then, the present work aims were: (1) to model the cytotoxicity effects of Salvia officinalis L. essential oil (SoEO) related to the human cancer cell lines kind (MCF-7 and HeLa) ; (2) to optimize the hydro-distillation extraction conditions of SoEO; and, (3) to determine the in vitro scavenging capacity of the free radicals DPPH•, NO•, ABTS+, and the ability to reduce Fe3+. Methods The cytotoxicity and anti-proliferative abilities were evaluated by measuring cell viability and then modeled. Two human cell lines: MCF-7 and HeLa were used. The optimization of SoEO extraction by hydro-distillation was carried out with Response Surface Methodology (RSM) using the Box–Behnken design Results The cytotoxicity activity against both tumor cell lines MCF-7 and HeLa was considerably important with IC50 = 3.125 and 8.920 µg/mL, respectively. All treated cell lines showed a significant reducing in cell viability in response to the increasing oil concentration. The relative behaviors of both cell lines under SoEO treatment were modeled. The obtained optimal extraction yield was Y = 1.85 g/100 g d.b. The main identified fractions were camphene (23.7%), α-thujone (19.62%), 1,8-cineole (10.6%), viridiflorol (5.9%), borneol (5.72%); β-thujone (5.4%); caryophyllene (3,83%). Also, SoEO was mostly able to scavenge DPPH• free radical, ABTS+ radical and hydrogen peroxide in an amount dependent manner (IC50 = 0.97, 0.279 and 0.05 mg/mL, respectively). Conclusion The present work provides a preliminary platform for further investigation of the possible mechanism of S. officinalis essential oils and their individual compounds in cytotoxic and antitumor activity.

This work deals with the optimization of the culture conditions of Bacillus invictae AH1 in order to increase the production level of the proteolytic activity. Response-surface methodology (RSM) was applied for the most significant fermentation parameters (concentration of wheat bran and K2 HPO4 /KH2 PO4 ) that were earlier identified by Plackett-Burman Design from seven possible factors. A central composite design was used and the quadratic regression model of producing active protease was built. A maximum protease activity was reached and validated experimentally, using a maximum wheat bran concentration (50 g/L) with increased K2 HPO4 /KH2 PO4 concentration (2.275 g/L). Protease production obtained experimentally coincident with the predicted value and the model was proven to be adequate. Interestingly, the use of RSM increased the protease production by four times (7,000 U/mL) using a low-cost substrate and a culture time of 40 hr, as compared to the standard culture conditions. In the second part of this study, a H2 O2 -tolerant alkaline protease produced from B. invictae AH1 with a molecular mass of about 41 kDa, noted P3, was purified by successive steps of ultrafiltration, gel filtration and ion exchange chromatography. The K m and Vmax values of the purified protease using casein, as substrate, were about 4 mg/mL and 27 μM/min, respectively. The highest enzyme activity was found at pH 9.0 and a temperature of 60°C. In addition, the enzyme showed a quasi-total stability against H2 O2 (5% for 1 hr) and against most of the tested solid and liquid detergents, suggesting its eventual use in bio-detergent formulations.

Having high cytotoxicity cell line effect, Cinnamomum zeylanicum Blume essential oil offers a novel approach to the chemotherapy treatment. In order to enhance its quantity/purity, the experimental conditions to produce essential oil should be more exploited. Steam distillation was used to isolate essential oil, and its conditions’ optimization was carried out with the surface-response methodology. The maximum amount (2.6 g/100 g d.b.) was obtained under minimum condensation water flow (0.8 mL/min), a sample size of 6.5 cm, a saline solution concentration of 262.5 g/L, and five washings. The produced essential oil contains >77% of polyphenols. In vitro cytotoxicity was examined using an MTT assay against HeLa and Raji cell lines. The essential oil’s capability to inhibit the proliferation of HeLa and Raji cell lines was studied under some conditions presenting IC50 values of 0.13 and 0.57 μg/mL, respectively. The essential oil was evaluated for its potential as an antioxidant by using in vitro models, such as phosphomolybdenum, DPPH, and H2O2 methods, in comparison with the synthetic antioxidant BHT (butylated hydroxytoluene) and ascorbic acid (vitamin C) as positive controls. The ammonium phosphomolybdate potency in the present study is of the order of 108.75 ± 32.63 mg of essential oil/equivalent to 1 mg of vitamin C in terms of antioxidant power, and the antioxidant activity of DPPH-H2O2 was 21.3% and 55.2%, respectively. The Cinnamomum zeylanicum Blume essential oil (CEO) covers important antioxidant and antiproliferative effects. This can be attributed to the presence of few minor and major phenolic compounds.

A new approach was proposed to model the extraction kinetics according to the operating parameters. This approach is based on the determination of the critical time tc (a characteristic time which depends on the operating parameters). It is necessary to start by collecting the experimental values of tc from experimental kinetics using the second derivation of extraction yield. Then, a full factorial design 23 is used to model tc as function of studied factors: temperature, solid-liquid ratio and ultrasonic power. The obtained expression of tc was used in second time as the basis of the modeling of extraction kinetics. It made possible to locate the inflection point that separates the two intervals of the extraction. To assure continuity in this point, we changed variable of time for the second phase of extraction and we started fitting from the last calculated point from the first phase. Seven models were tested to fit studied kinetics. A mathematical model was proposed to express tc according to the operating parameters of the studied extraction. Patricelli (composed of two exponential terms) and the exponential models showed the best fitting results for all experiments. Patricelli model fitted very well the first phase of experiments and the exponential model fitted the second phase. This confirms a new coupled washing/diffusion hypothesis of extraction performing in three steps: washing, first diffusion step, and second diffusion step.

Background The present study was focused on the optimization of yield of the essential oil extraction from leaves of Lawsonia inermis, and the determination of chemical composition, antioxidant activities, and lipid peroxydation and antiproliferative effects. Methods Henna essential oil (HeEO) were extracted by hydrodistillation; the identification of the chemical composition were done by GC/MS method. HeEO was analyzed for antioxidant power in: (1) chemical system by the DPPH test, the ABTS test and the total antioxidant activity test; and (2) in biological system by lipid peroxydation tests (MDA and DC) in cells culture. The cytotoxicity effects of HeEO were assessed using MTT assay against Raji and HeLa cell lines. Results The optimal extraction yield was 6.8 g/100 g d.b. HeEO showed a remarkable anti-oxidant activities including DDPH (42%), ABTS (87%) and the power of ammonium phosphomolybdate (2992 ± 230 mg of HeEO by equivalent to 1 mg of vitamin C in terms of total antioxidant power). Conclusion Beyond notable antioxidant activities of the HeEo, our results showed a significant decrease in the production of ERO in the Raji cell line. The anti-tumor power of the Henna essential oil shows an interesting cytotoxicity effect (IC50 at 0.26 μg/mL for Raji and at 1.43 μg/mL for HeLa) with a total mortality percentage reaching 60%, for both.

Background Three steps are very important in order to produce microalgal lipids: (1) controlling microalgae cultivation via experimental and modeling investigations, (2) optimizing culture conditions to maximize lipids production and to determine the fatty acid profile the most appropriate for biodiesel synthesis, and (3) optimizing the extraction of the lipids accumulated in the microalgal cells. Methods Firstly, three kinetics models, namely logistic, logistic-with-lag and modified Gompertz, were tested to fit the experimental kinetics of the Chlorella sp. microalga culture established on standard conditions. Secondly, the response-surface methodology was used for two optimizations in this study. The first optimization was established for lipids production from Chlorella sp. culture under different culture conditions. In fact, different levels of nitrate concentrations, salinities and light intensities were applied to the culture medium in order to study their influences on lipids production and determine their fatty acid profile. The second optimization was concerned with the lipids extraction factors: ultrasonic’s time and temperature, and chloroform-methanol solvent ratio. Results All models (logistic, logistic-with-lag and modified Gompertz) applied for the experimental kinetics of Chlorella sp. show a very interesting fitting quality. The logistic model was chosen to describe the Chlorella sp. kinetics, since it yielded the most important statistical criteria: coefficient of determination of the order of 94.36%; adjusted coefficient of determination equal to 93.79% and root mean square error reaching 3.685 cells · ml− 1. Nitrate concentration and the two interactions involving the light intensity (Nitrate concentration × light intensity, and salinities × light intensity) showed a very significant influence on lipids production in the first optimization (p

International audience; The aim of this study is to predict Tetraselmis cells growth-kinetic and to induce the synthesis of bioactive compounds (chlorophylls, carotenoids and starch) with high potential for biotechnological applications. Using the statistical criteria, the Baranyi-Roberts model has been selected to estimate the microalgae growth-kinetic values. The simultaneous effects of salinity, light intensity and pH of culture medium were investigated to maximize the production of total chlorophylls, carotenoids and starch. The optimal culture conditions for the production of these compounds were found using Box-Behnken Design. Results have shown that total chlorophyll and carotenoids were attained 21.6mg·g-1DW and 0.042mg·g-1DW, respectively. In addition, the highest starch content of 0.624g·g-1DW has been obtained at neutral pH with high irradiance (182μmolphotonsm-2 s-1) and low salinity (20). A highly correlation (R2 = 0.884) has been found between the gravimetric and flow cytometric measurements of chlorophyll content.

The present study is conducted to investigate the effect(s) of ultrasonic pretreatment on the extraction of essential oils from dried leaves of lemongrass (Cymbopogon flexuosus) by hydro-distillation. The drying process was carried out within a forced convective dryer at 50 °C and a drying air velocity of 1 m/s. Using a response surface methodology (RSM) based on central composite design with the face centered, the obtained optimum conditions were as follows: an ultrasound pretreatment for 25 min within a power of 250 W, at 50 °C. Modeling showed that all factors (time, power and temperature) were found to be highly significant in the extraction process (p

This study aimed to optimize mixtures of whey protein concentrate (WPC) and two flours of rice and maize flours for the production of gluten-free sponge cakes. This was obtained by using mixture design methodology. WPC incorporation had positive effects on specific volume and baking loss of cakes, whilst, their incorporation increased their hardness. Considering all cakes properties, two formulas F1 (78.5% Maize, 15% Rice and 6.5% WPC) and F2 (82.4% Maize, 12% Rice and 5.6% WPC) were optimized using a mixture design. The microstructure F1 was more organized and very well structured with smaller aggregates. According to the organoleptic evaluation, F1 was also most appreciated by the tasting panel. The findings of the present study indicated that maize and rice flours, and WPC could be used as a substitute for wheat flour in producing sponge cakes of high quality.

Due to the high consumption rate of fermented milk products such as yogurt, the fortification of these products will effectively reduce diseases associated with nutritional deficiencies. In the present study, after incorporating Spirulina into yogurt at four different concentrations (0.25, 0.5, 0.75 and 1%), we studied its effect on the fermentation process, texture, nutraceutical and sensory characteristics of yogurt. The addition of 0.25% of Spirulina was significantly sufficient to accelerate the end of fermentation (p

This work deals with the optimization of the culture conditions of Bacillus invictae AH1 in order to increase the production level of the proteolytic activity. Response-surface methodology (RSM) was applied for the most significant fermentation parameters (concentration of wheat bran and K

Lately, microalgae have been used as natural additives in fish-transformed products to improve their nutritional quality. In this research, the effects of adding Spirulina platensis at concentrations of 0.5, 1 and 1.5% w/v on both the texture and the sensory characteristics of canned burgers were studied. In fact, the addition of Spirulina platensis to fish burgers improves their nutritional composition. Compared to the results of the other fish burger treatments, the treatments that contain 1% of Spirulina platensis had better texture and sensory properties (p &lt, 0.05). Besides, these treatments showed higher swelling ability as well as water and oil holding capacities, due to the important dietary fibers and polysaccharides contents found in Spirulina platensis. No mold or foodborne pathogens were detected in any of the canned burgers up to 8 months of storage at 4 &deg, C. Furthermore, burgers prepared with Spirulina were distinguished by the lowest mean (a* and b*) values (p &lt, 0.05), which shows that the yellow color gradually diminished towards a greenish color. Because of the presence of polysaccharides and pigments (chlorophylls, carotenoids and phycocyanin), Spirulina platensis considerably ameliorates the antioxidant activities of the newly prepared fish burgers. On the whole, we can conclude that Spirulina platensis can be used as a nutritious additive to produce new fish-based products with high alimentary qualities.

The textiles manufacturing is one of the core industries that release a huge amount of dyes during the dyeing process. As a result, the growing demand of an efficient and low-cost treatment has given rise to alternative adsorbents. In the present study, prickly pear cactus cladodes powder (PPCP) of Opuntia ficus indica was investigated as an ecofriendly and low-cost biosorbent of Acid orange 51 (AO51) and Reactive Red 75 (RR75) dyes commonly used in dyeing. The FTIR spectroscopic characterization of PPCP showed the heterogeneity in surface structure and functional groups which confers to the biosorbent its capability to interact with acidic (AO51) and reactive (RR75) dyes molecules. Effects of pH, temperature, initial dye concentration and adsorbent dose on adsorption yield were investigated. The dyes uptake process was closely fitted to the pseudo-second order kinetic for both dyes. Experimental data were analyzed by applying the Langmuir, Freundlich, Dubinin–Raduskevich, Temkin, Redlich–Peterson, and BET isotherms equations. The models of BET and Langmuir were considered as the best isotherms models fitting experimental data, respectively, of RR75 and AO51. The maximum Langmuir monolayer biosorption capacities were of 198.9 and 45 mg g(−1), respectively for RR75 and AO51.

Multi-contaminated industrial wastewaters pose serious environmental risks due to high toxicity and non-biodegradability. The work reported here evaluated the ability of Pseudomonas aeruginosa strain Gb30 isolated from desert soil to simultaneously remove cadmium (Cd) and Reactive Black 5 (RB5), both common contaminants in various industrial effluents. The strain was able to grow normally and decolorize 50 mg L−1 RB5 within 24 h of incubation in the presence of 0.629 m mol L−1 of Cd2+. In order to evaluate strain performance in RB5 detoxification, a cytotoxicity test using Human Embryonic Kidney cells (HEK293) was used. Cadmium removal from culture media was determined using atomic adsorption. Even in presence of (0.115 + 0.157 + 0.401 + 0.381) m mol L−1, respectively, of Cr6+, Cd2+, Cu2+ and Zn2+ in the growth medium, strain Gb30 successfully removed 35% of RB5 and 44%, 36%, 59% and 97%, respectively, of introduced Zn2+, Cu2+, Cr6+ and Cd2+, simultaneously. In order to understand the mechanism of Cd removal used by P. aeruginosa strain Gb30, biosorption and bioaccumulation abilities were examined. The strain was preferentially biosorbing Cd on the cell surface, as opposed to intracellular bioaccumulation. Microscopic investigations using AFM, SEM and FTIR analysis of the bacterial biomass confirmed the presence of various structural features, which enabled the strain to interact with metal ions. The study suggests that Pseudomonas aeruginosa Gb30 is a potential candidate for bioremediation of textile effluents in the presence of complex dye-metal contamination.

This paper presents the experimental study conducted on a clayey soil originating from the region of Beja, north-west of Tunisia. The evaporation, shrinkage and permeability behaviours were studied. The Soil Water Retention Curve (SWRC) was determined from the slurry state to dry state, under the desiccation path (called initial drying curve). The Crack Intensity Factor (CIF), settlement and void ratio were also studied to characterise the shrinkage phenomenon during desiccation. Moisture content (ω), saturation degree (Sr) and evaporation rate (Re) evolutions during desiccation path were also presented. This type of slurry clay presents three stages during the desiccation process (pendular, funicular and capillary regimes). During desiccation process, the evaporation rate presents a linear relationship as a saturation degree function. Furthermore, the evaporation rate versus suction presents two phases: quasi-saturated and unsaturated states. This paper introduces a study of the hygroscopic and mechanical parameters naturally modified during a desiccation process and proposes some analytical models to describe clay behaviour. Using these parameters, we can determine the intrinsic permeability during the desiccation process.

Background This study aimed to maximize biomass concentration, biomass productivity and biochemical composition of the marine microalga Tetraselmis sp. Methods In the current study, Box-Behnken Design was used to model the effect of NaNO3, NaH2PO4, metals and vitamins in the F/2 medium on the growth, total chlorophylls, carotenoids and starch contents. The total chlorophylls content was quantified by spectrophotometry. The FT-IR spectroscopy was used to estimate the biochemical compositions of Tetraselmis sp. grown under both optimized medium culture for starch production and standard culture medium. Results Finalized NaNO3 (1.76 mM), NaH2PO4 (0.018 mM), metals (1500 μL.L−1) and vitamins (312.5 μL.L−1) concentrations, generated an increase in biomass concentration up to 5.72 g.L−1 which contributed to an increase about 2.4-fold than that of the standard conditions of biomass productivity (408.57 mg.L−1.day−1). The maximum value of carotenoids content (0.3 mg.g DW−1) was achieved at the highest level of all factors. The total chlorophylls content reached also its maximum (5.18 mg.g DW−1) at high nitrate (1.76 mM), phosphate (0.054 mM), metals and vitamins concentrations, while the maximum starch content (42% DW) was achieved with low nitrate and phosphate concentrations (0.58 mM and 0.027 mM) and with metals and vitamins limitations. Thus, the nitrogen, phosphorus, metals and vitamins limitations led to divert the metabolism for the starch biosynthesis. Conclusions The high biomass concentration productivity and starch production make Tetraselmis sp. strain a good candidate for biotechnological applications.

Microalgae have been used as natural ingredients to produce functional and nutritional food products. The impact of the addition of Chlorella minutissima, Isochrysis galbana, and Picochlorum sp. at concentrations of 0.5, 1, and 1.5% w/v on the texture and sensory attributes of canned burgers were investigated. The results show that carp formulations containing 1% microalgae show significantly better classification performance for many textural and sensory parameters compared to the rest of the formulations. Also, these treatments had higher swelling ability as well as water and oil holding capacities, thanks to the important dietary fiber and polysaccharide contents found in microalgae. Moreover, microalgae-supplemented burgers were characterized as having low a* and b* values, which made the color appear to be pale orange. Additionally, thanks to its richness in pigments and polysaccharides, microalgae considerably ameliorated the antioxidant activities of the new prepared fish burgers. Thus, microalgae could be used as natural and nutritious ingredient to develop new fish-based products.

The composition of the Tunisian Tomato TT reflects a very important nutritional value In fact the TT is rich in fiber g g d m protein g g d m and also potassium mg g d m which is an essential micronutrient for humans thanks to its role in reducing the risk of hypertension This renders the TT one of the major sources of this important mineral nutrient An experimental determination of TT rsquo s sorption isotherm is carried out at and deg C using the method of saturated salt solutions The sorption curves are then approximated by twelve empirical models The Peleg model yields the best fitting for both temperatures and for des adsorption phenomenon Drying of TT slices is carried out at the same two temperatures and deg C and two air velocities and m s The convective drying characteristics of TT slices are established in a pilot dryer to assess the effect of drying air conditions on drying kinetics Also twelve different drying models are tested and compared according to their standard error and correlation coefficients to fit TT drying curves The Logarithmic model shows the best fitting for all drying curves on all tested conditions

In the present work, a diffusion-based model was adopted to represent the convective drying behavior of cylindrical banana samples, taking into consideration the shrinkage along drying. The developed model simulated a significant number of situations resulting from the variations of some operating conditions. The temperatures tested were 50, 60, 67 and 70 °C, the air velocities were 3, 4 and 4.5 m/s and the relative humidity range of the drying air was from 3.5 to 11.5%. The calculated drying curves were compared to the experimental ones in order to determine apparent moisture diffusivity. An empirical equation was suggested, describing the apparent moisture diffusivity within the banana versus product temperature and local moisture content. A good agreement was found between experimental and calculated drying kinetics.

Desorption isotherms of sardine muscles were determined at three temperatures (25, 35 and 50 °C) for a water activity range varying from 0.10 to 0.75. Gravimetric static methods using saturated salt solutions were used (continuous and discontinuous measurements). Six models were taken from the literature to describe experimental desorption isotherms. The OSWIN model shows the best fit of the experimental data. The net isosteric heat of desorption and the isosteric heat of desorption were determined by using the CLAUSIUS–CLAPEYRON equation. The isosteric heat of desorption decreases continuously with the increase of the equilibrium moisture content. A mathematical correlation was established between the isosteric heat of desorption and equilibrium moisture content.

Experimental drying curves of sardine muscles ( Sardinella aurita ) in parallelepiped form were performed under different drying air conditions (three air temperatures: 35, 40 and 50 °C ± 1 °C, two air velocities: 1 and 2.5 m s −1 , and at atmosphere humidity). A diffusive three-dimensional model was established to describe drying of sardine sample in parallelepiped form. The calculated drying curves was compared to the experimental ones in order to determine apparent moisture diffusivity. An empirical equation describing the apparent moisture diffusivity within the sardine muscles was suggested versus temperature and local moisture content of the product. A good agreement was found between experimental and calculated drying kinetics.

Kinetics of aqueous extraction of polyphenols from carob (Ceratonia siliqua L.) have been performed in different conditions (Temperature = 40 and 60C; solid–liquid ratio = 1:3 and 1:19 and without and with ultrasonic assistance (100W)). The effects of various parameters were studied using an experimental design. The final yield was modelled as a first order polynomial model: (p

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The study of the isotherms desorption of olive mill wastewater (OMW) was investigated to describe its water activity under different saturated environments. The microbial biodegradation of OMW during its storage in 5 evaporation ponds located in Agareb (Sfax-Tunisia) was carried out during the oil-harvesting year held 105 days in 2004. Gravimetric static method using saturated salt solutions was used and OMW as placed at 30 degrees C and under different water activities ranging from 0.11 to 0.90. Eight models were taken from the literature to describe experimental desorption isotherms. During storage, the evolution of physico-chemical parameters including pH, temperature, evaporation, humidity, total phosphorus, chemical oxygen demand (COD), biological oxygen demand (BOD) and phenols and three microbiological flora (aerobic mesophilic bacteria, yeasts and moulds) were considered. At 30 degrees C, when relative humidity increased in the experimented ponds of 69, 84 and 90%, the evaporation speed decreased from 1.24 x 10(-5) to 5 x 10(-6) cm(3) s(-1), from 6 x 10(-5) to 7 x 10(-6) cm(3) s(-1) and from 5 x 10(-6) to 1.1 x 10(-7) cm(3) s(-1) respectively. The desorption isotherm exhibited a sigmoidal curve corresponding to type II, typical of many organic material. The GAB and Peleg models gave the best fit for describing the relationship between the equilibrium moisture content and water activity in OMW (R (2) = 0.998). During the storage period, the analysis showed an increase of all the physico-chemical parameters studied, except phenols and total phosphorus concentrations. The microbiological study showed the predominance of yeasts and moulds and the decrease of bacteria population after 75 days reflecting both effect of recalcitrant compounds and the water activity on microbial growth.