Francisco A. Riera

A new integrated membrane process for producing clarified apple juice and apple juice aroma concentrate

An integrated membrane process for producing apple juice and apple juice aroma concentrates is proposed. The process involves the following operations: an integrated membrane reactor to clarify the raw juice; reverse osmosis (RO) to preconcentrate the juice up to 25°Brix; pervaporation (PV) to recover and concentrate aroma compounds, and a final evaporation step to concentrate apple juice up to 72°Brix. These operations were tested in laboratory and pilot plant units. Promising results were obtained with the membrane operations involved. In order to have an economic process assessment, the pilot plant units were assembled into an integrated unit and operated with raw apple juice. The products were more clear and brilliant than apple juice produced by conventional methods. The integrated membrane process also seemed to be more advantageous on the basis of economics than the conventional one.

Recovery and concentration by electrodialysis of tartaric acid from fruit juice industries waste waters

Abstract: Electrodialysis (ED) has been used as a membrane technique to con-centrate tartaric acid from ion exchange regeneration waters obtained in grapejuice treatment. The initial ion tartrate concentration in these streams variesbetween 1 and 10 kg m~3 and can be concentrated more than 60% (53E2kgm~3after 13300 s). Permeate Nux of other common ionic components has beenshown. Optimum intensities and current efficiency have been calculated with syn-thetic solutions. A mathematical approach has been used to predict Ðnal tartaricacid concentration and electro-osmotic e†ects.J. Chem. Technol. Biotechnol. 70, 247E252 (1997)No. of Figures: 5. No. of Tables: 4. No. of Refs: 15Key words: tartaric acid, electrodialysis, waste waters, recovery, fruit juice NOTATIONA Membrane area per cell-pair (m2)C Solute concentration (mol m~3)F FaradayIs constant (A s eq~1)i Current density (A m~2)J Massic solute Nux (kg m~2 s~1)JwVolumetric water Nux (m s~1)m Anion mass (kg)n Number of cell-pairs (dimensionless)N Normality (eq m~3)S Electrode surface (m2)t Time (s)V Batch or solution volume (m3)a Constant in eqn (2) (m~3 g~1)b Constant in eqn (2) (s m~3 g~1)g Current efficiency (dimensionless)Subscriptsc Related to the concentrated streamw Related to water transport

Permeate flux prediction in apple juice concentration by reverse osmosis

This work studies apple juice concentration by reverse osmosis (RO) using polyamide tubular membranes at different operating conditions. Permeate flux has been predicted by using the solution-diffusion model combined with the film model. Good agreement was found between the experimental values and the ones calculated by using both models. Pressure was found to be the most important variable controlling the process. Physico-chemical analyses were made in order to evaluate the quality of concentrated apple juice.

Skimmed milk demineralization by electrodialysis: Conventional versus selective membranes

Abstract Electrodialysis (ED) is a membrane technique that is useful in the demineralization of dairy products. In this work, experimental results obtained in batch electrodialysis of skimmed milk are presented. Two kinds of membranes were used: the first kind were conventional membranes in PVC and the second were monovalent ion selective membranes which are now available on the market. This latter type of membrane permits the transport of monovalent ions but limits the passage of large ions which have a high valency. The limiting current was measured as a function of feed flow into the stack. The results obtained when using both types of membranes were compared for elimination rate of K + , Na + , Cl −1 , Ca 2+ , Mg 2+ and PO 4 3− ions as well as for current efficiency and electric power consumption in the separation process.

Caseinomacropeptide behaviour in a whey protein fractionation process based on α-lactalbumin precipitation

This work studied the behaviour of caseinomacropeptide (CMP) in a whey protein fractionation process based on the selective precipitation of α-lactalbumin (α-la) in an acid medium. Three different acids (hydrochloric, citric and lactic) and different operating conditions (protein concentration, temperature and pH) were considered to perform the precipitation step. Under the optimised precipitation conditions obtained for α-la (pH 4, 55°C, initial α-la concentration around 12 g/l) CMP presents quite similar behaviour to that observed for β-lactoglobulin (β-lg), namely remaining in the supernatant fraction. However, at a lower pH value (3.5) the amount of precipitated CMP increases up to 72% when citric acid is added. This behaviour could be due to the fact that CMP is close to its isoelectric point, which allows a supernatant fraction enriched in β-lg that is almost free from the rest of proteins in sweet whey.

ATR-FTIR spectroscopy for the determination of Na4EDTA in detergent aqueous solutions.

Fourier transform infrared spectroscopy in the attenuated total reflectance mode (ATR-FTIR) combined with partial last square (PLS) algorithms was used to design calibration and prediction models for a wide range of tetrasodium ethylenediaminetetraacetate (Na4EDTA) concentrations (0.1 to 28% w/w) in aqueous solutions. The spectra obtained using air and water as a background medium were tested for the best fit. The PLS models designed afforded a sufficient level of precision and accuracy to allow even very small amounts of Na4EDTA to be determined. A root mean square error of nearly 0.37 for the validation set was obtained. Over a concentration range below 5% w/w, the values estimated from a combination of ATR-FTIR spectroscopy and a PLS algorithm model were similar to those obtained from an HPLC analysis of NaFeEDTA complexes and subsequent detection by UV absorbance. However, the lowest detection limit for Na4EDTA concentrations afforded by this spectroscopic/chemometric method was 0.3% w/w. The PLS model was successfully used as a rapid and simple method to quantify Na4EDTA in aqueous solutions of industrial detergents as an alternative to HPLC-UV analysis which involves time-consuming dilution and complexation processes.

Advancements in the Fractionation of Milk Biopeptides by Means of Membrane Processes

Nowadays the most common way to obtain bioactive peptides is by enzymatic hydrolysis of protein solutions. The most studied substrates used to produce bioactive peptides are milk proteins in the form of co-products from dairy industries: caseins, cheese whey, buttermilk, whey protein concentrates and isolates or even pure single proteins that can be obtained at a reasonable price on an industrial scale (e.g. β-lactoglobulin, β-Lg).

Influence of heat pre-treatment on BSA tryptic hydrolysis and peptide release.

In contrast with other food proteins, such as β-lactoglobulin or caseins, intensely studied for bioactive peptide production, relatively little attention has been paid to serum albumin, the main blood protein, even though blood disposal is a severe problem for meat processors. In this study, serum albumin was hydrolysed with trypsin after several heat treatments and using different enzyme concentrations. The degree of hydrolysis reached and the peptide sequences released over time were evaluated. Large differences in enzyme-to-substrate ratios (1:50, 1:100 and 1:200) led to similar degree of hydrolysis values (31.92±1.43%, 31.08±3.09% and 26.21±0.71%), and did not alter the number of peptides released. However, thermal treatment enhanced significantly (p<0.05) both the degree of hydrolysis (up to 50.41±1.90%) and the number and amount of the majority of peptides obtained, all with potential bioactivity (28 peptides in the native hydrolysate, 39 in the thermally treated).

Membrane Separation Process in Wastewater Treatment of Food Industry

Wastewater derived from food production is highly variable, depending on the specific types of food processing operations (e.g., fruit, vegetable, oils, dairy, meat, and fish). Advances in membranes technology have showed many advantages for wastewater treatment of food industry. By implementing membranes, the separated substances and clean water are often recoverable in a chemically unchanged form and are therefore easily re-used. Maximum benefits are obtained when one or both the output streams from the membrane system are recycled or re-used, thereby reducing process materials requirement and minimizing waste disposal costs. This chapter reviews the development and applications of membrane processes in wastewater treatment of food industry. Particular focus is given to membrane’s special abilities to wastewater treatment for water regeneration and various re-uses purposes. Influence of engineering aspects is analyzed, specially operating conditions near critical flux to improve processes in wastewater treatment. Detailed discussions are provided with respect to constituents of concern in water reuse applications including recovery of other products with value for food industry.

Antioxidant Activity and Functional Properties of Polymerized WheyProducts by Glycation Process

The antioxidant properties of sweet and acid whey products were incremented by polymerization of their proteins by glycation of whey protein concentrates (WPC) and their hydrolyzates (WPCH) with ribose and glucose in individual experiments under similar concentration. Heating at 50°C during 20 h maximum and pH 7 and pH 9 were used in all tests. The higher activity was found in WPC glycosylates products with ribose at pH 7 and heating during 10–15 h. In comparable form, antioxidant activity in WPCH was incremented by prior hydrolysis to glycation with 25–45% of hydrolysis degree. Further functional properties of whey proteins (solubility, emulsion, and foam) were also improved by the polymerization with ribose. The color of polymerized products due to Maillard reactions was associated with antioxidant activity of each compound; however comparative color in glycosylates products with glucose and ribose did not show this effect.