Fabrice Vaillant

Concentration of passion fruit juice on an industrial pilot scale using osmotic evaporation

Osmotic evaporation to concentrate clarified passion fruit juice was tried out on an industrial scale. A pilot plant that was equipped with a module containing 10.2 m(2) of polypropylene hollow fibres was used to concentrate passion fruit juice up to a total soluble solids (TSS) content higher than 60 g/100 g at 30 degreesC. Tangential velocity, temperature and concentration of solutions significantly influenced evaporation flux. An average evaporation flux of almost 0.75 kg h(-1) m(-2) was obtained with water, 0.65 kg h(-1) m(-2) when juice was concentrated to 40 g TSS/100 g and 0.50 kg h(-1) m(-2) when it reached 60 g TSS/100 g. A long-term trial, lasting 28 m(-2), was successfully carried out without membrane fouling. Osmotic evaporation can be also conducted as a multistage procedure, giving a constant evaporation flux of around 0.62 kg h(-1) m(-2) when juice was concentrated from 14 to 60 g TSS/100 g. Sensory quality and vitamin C content were well preserved in the concentrated juice

Strategy for economical optimisation of the clarification of pulpy fruit juices using crossflow microfiltration

Abstract Microfiltration, using a mineral tubular membrane with nominal pore diameter of 0.2 μm, was applied to six tropical fruit juices (mango, pineapple, naranjilla, Castillas blackberry, passion fruit, tangerine) after partial enzymatic liquefaction. For passion fruit juice, it was found that, when estimating the total costs of producing clarified juice to volumetric reduction ratio (VRR) specifications, a VRR exists at which these costs are minimal. Nevertheless, for juices with a high pulp content, these optimal economic costs are reached at relatively low VRR, inducing a low processing yield and costs that are too high for the expected selling price. For the process to be more efficient, it was found that the retentate must have a commercial value close to that of the original raw juice. The kinetics of liquefying and concentrating the suspended solid (SS) during enzymatic treatment and microfiltration were monitored for all juices tested. It was shown that, by controlling the VRR, increasing the SS content was possible until it reached the same concentration level found in the raw juice. Under these conditions, the retentate is very similar to the initial juice and can be re-introduced into the pulpy juice processing line. This strategy was carried out on the pulpy juices, following a fully continuous processing with constant feeding and removal of retentate so as to keep the SS content constant in the emerging retentate. During these trials, the permeate flux fluctuated around an average value without showing signs of decreasing. Estimated production costs were also much more competitive.

Thermal degradation kinetics of anthocyanins from blood orange, blackberry, and roselle using the Arrhenius, Eyring, and Ball models.

Anthocyanin stability was assessed over temperatures ranging from 30 to 90 degrees C for seven products: blood orange juice [Citrus sinensis (L.) Osbeck]; two tropical highland blackberry juices (Rubus adenotrichus Schlech.), one with high content and the other with low content of suspended insoluble solids (SIS); and four roselle extracts (Hibiscus sabdariffa L.). The blackberry juice showed the highest content of anthocyanins with 1.2 g/L (two times less in the roselle extracts and 12 times less in the blood orange juice). The rate constant for anthocyanin degradation and isothermal kinetic parameters were calculated according to three models: Arrhenius, Eyring, and Ball. Anthocyanins in blood orange juice presented the highest rate constant for degradation, followed by the blackberry juices and roselle extracts. Values of activation energies were 66 and 37 kJ/mol, respectively, for blood orange and blackberry and 47-61 kJ/mol for roselle extracts. For the blackberry juices, a high SIS content provided only slight protection for the anthocyanins. The increasing content of dissolved oxygen, from 0.5 to 8.5 g/L, did not significantly increase the rate constant. For both isothermal and nonisothermal treatments, all three models accurately predicted anthocyanin losses from different food matrices.

Crossflow microfiltration of passion fruit juice after partial enzymatic liquefaction

To obtain clarified passion fruit juice, crossflow microfiltration after enzymatic liquefaction was studied using ceramic membranes with 0.2 μm pore size. The effect of a high-rate enzymatic treatment for the degradation of suspended solids was assessed, resulting in the selection of a commercial enzymatic preparation. Partial enzymatic liquefaction of cell-wall polysaccharides prior to microfiltration provided an unusual pattern of flux increase after a short decline when crossflow velocity was high (7 m s−1). It was found that a synergistic effect between pectinase and cellulase activities enhanced permeate flux increase. With total recycling at 36°C, the combination of low transmembrane pressure (150 kPa) and high enzyme concentration (1 ml l−1) provided the highest flux (113 l h−1 m−2). These conditions were then assessed with concentration in order to verify industrial feasibility and evaluate physico-chemical characteristics of final products. A volumetric reduction ratio of 3 was maintained during 18 h without any decrease in permeate flux, which fluctuated around 40 l h−1 m−2. The quality of permeate was satisfying even its aromatic strength was weakened. Retentate had similar characteristics of raw juice and could be recycled in order to use its residual enzyme activity.

Co-immobilized pectinlyase and endocellulase on chitin and Nylon supports

Abstract Some factors influencing easy immobilization procedures on Nylon and chitin supports were optimized in terms of the highest activity of immobilized pectinlyase, using two experimental designs. Optimal procedures were applied to co-immobilized pectinlyase (Pl, EC 4.2.2.3) and endocellulase (Cx, EC 3.2.1.4), using a commercial enzyme but omitting preliminary purification steps. Purified enzyme solutions were not used. The kinetic characteristics of co-immobilized pectinlyase and endocellulase were assessed for both supports. Chitin was more suitable for applications to fruit juice liquefaction because both immobilized pectinlyase and endocellulase showed higher activity at low pH and low temperature. Furthermore, the half-life of pectinlyase bound to chitin was higher than with Nylon (407 h against 19 h). The immobilization procedure on chitin was not only inexpensive, but also very easy to carry out so that the potential for industrial application is considerable.

Comparison of different methods for deacidification of clarified passion fruit juice

Abstract The high acidity of passion fruit limits its addition in food preparation. In order to easy the uses of this juice to formulate high aroma and flavour products, its citric acid content must be decreased. Various methods such as calcium salts precipitation, ion-exchange resins and electrodialysis with homopolar and bipolar membranes were investigated to increase the pH of a clarified passion fruit juice from 2.9 to 4.0. Each deacidification process was compared in terms of characteristics of deacidified juices such as concentration of inorganic and organic ions, colour and flavour. The deacidification by precipitation using CaCO 3 was not recommended because of CO 2 release. The ion-exchange process gave a poor quality juice in terms of organoleptic characteristics. Electrodialysis with homopolar membranes induced an increase in the sodium concentration. Precipitation with Ca(OH) 2 and electrodialysis with bipolar membrane were the most suitable processes in terms of sensorial properties of juices treated. The physico-chemical analyses showed an increase in the calcium concentration with the use of Ca(OH) 2 that could cause some precipitation problems in the final product. Inorganic anions were eliminated together with citrate by using electrodialysis and resins. Nevertheless, electrodialysis with bipolar membranes presented great advantages: it was a continuous process without reagent addition moreover allowing the production of a valuable solution of citric acid.

Kinetics of anthocyanin degradation and browning in reconstituted blackberry juice treated at high temperatures (100-180°C).

Monomeric anthocyanin degradation and nonenzymatic browning (NEB) index have been determined in reconstituted blackberry juice heated at high temperature in a hermetically sealed cell. Statistical analysis demonstrated that, when the temperature range (100-180 degrees C) was divided into two subranges (100-140 and 140-180 degrees C) for anthocyanin degradation, reaction kinetics were well represented by two sequential first-order reactions. The activation energy for NEB from 100 to 180 degrees C (106 kJxmol(-1)) was slightly higher than the anthocyanin value at the lower temperature range (92 kJxmol(-1)), but was more than twice the value for the higher range (44 kJxmol(-1)). The reaction rate constant at 140 degrees C for anthocyanin degradation (3.5 x 10(-3) s(-1)) was two times that for the NEB index (1.6 x 10(-3) s(-1)). Hence, anthocyanin degradation was faster than the appearance of NEB products. The non-isothermal method developed allows estimating kinetic parameters and thereby generating temperature profiles of heat processes that would help preserve the nutritional properties of foods during high-temperature processes.

Metabolic Fate of Ellagitannins: Implications for Health, and Research Perspectives for Innovative Functional Foods

Consumption of dietary ellagitannins (ETs) has been associated with different health benefits. Nonetheless, ETs are not bioavailable as such and are metabolized in vivo. They are partially converted into ellagic acid (EA) in the upper gastrointestinal (GI) tract, but this first metabolite is also poorly bioavailable. In the lower GI tract, EA and residual ETs are metabolized by gut microbiota to produce urolithins, which, together with their conjugate relatives, persist at relatively high concentrations in plasma and urine for days after ingestion of dietary ETs. Thus, ETs and EA may exert local health benefits on the GI tract but systemic health benefits are more likely to result from urolithins. Cellular models suggest that, at physiological concentration, urolithins are active against chronic degenerative diseases. Health benefits have been proven in animal models and during clinical studies. Even so, the crucial involvement of gut microbiota in ET bioconversion induces important variability of physiological response among humans, giving rise to the concept of high and low urolithin producers. This variability among consumers in obtaining potential health benefits from dietary ETs raises new challenges for the functional food industry. Different research perspectives are discussed to tackle this significant issue for nutritionists, food technologists, and consumers.

Osmosonication of blackberry juice: impact on selected pathogens, spoilage microorganisms, and main quality parameters.

UNLABELLED Osmosonication combines ultrasound with nonthermal concentration. It was applied on tropical highland blackberry (Rubus adenotrichus) juice over different periods of time to assess reductions in microorganism and the impact on main quality parameters. This juice had been inoculated with Salmonella spp., Shigella sp., a lactic acid bacterium, yeasts, and molds. It was then sonicated for 5.9 to 34.1 min at 20 kHz and 0.83 W/mL. Nonthermal concentration was simulated by mixing the juice with a concentrate to obtain 650 g TSS/kg. It was then stored at -18 °C for up to 82 h. The lactic acid bacterium, yeasts, and molds were reduced by 1.60 to as much as 5.01 log(10) CFU/mL, whereas, for pathogens, reductions were total ≥7.1 log(10) CFU/mL after 24 h of storage, even for juice not sonicated, because of low pH. Color, antioxidant capacity, anthocyanins, and ellagitannins did not change significantly during sonication treatment up to 32 min. However, an off-flavor was detected after 8 min of sonication. Nonetheless, osmosonication can be considered as an alternative to thermal processes for producing safe and high-quality concentrates. PRACTICAL APPLICATION Osmosonication represents a potential processing alternative for producing safe and high-quality concentrated fruit juice without applying thermal treatments. Findings reported in this article can also be applied by industries when concentrating juices by classical means at relatively low temperature. It provides industries with a mathematical model specific for blackberry juice, from which different combinations of sonication time and storage time of concentrate can be chosen to achieve safety and quality goals.

Impact of the extraction procedure on the kinetics of anthocyanin and colour degradation of roselle extracts during storage

BACKGROUND The stability of anthocyanins and colour of aqueous extracts from roselle (Hibiscus sabdariffa L.) was investigated during storage at 4-45 °C. The effect of the extraction procedure (cold or hot extraction with or without pasteurisation) on the kinetic behaviour was determined. RESULTS Data analysis showed first-order kinetics for the evolution of anthocyanin content, colour density, colour strength and browning index. Three models (Arrhenius, Eyring and Ball) were used to represent the temperature dependence of the reaction rates. The three models allowed the prediction of colour modifications according to the storage temperature over 6 months. Activation energies ranged from 22 to 26 kJ mol(-1) for anthocyanin degradation and from 18 to 34 kJ mol(-1) for colour parameter modification. The degradation rate during storage depended on the extraction procedure. When heated, the extracts were clearly less stable. Their colour changed faster during storage especially when hot water and pasteurisation were used. CONCLUSION Although the anthocyanin content and initial colour were not modified, the extraction conditions, especially temperature, greatly affected the stability of the extracts during storage. Further studies are needed to understand the mechanisms involved.