Effect of ultrasound on the mass transfer and physical changes in brine bell pepper at different temperatures

Mass transfer and physical attributes of red bell pepper were evaluated. Pepper strips were placed into brine of constant concentration at different temperatures (25–55 °C) with immersion times ranging from 15 to 480 min with and without ultrasound treatment. Diffusion coefficients were evaluated for calcium, sodium, citric acid, soluble and total solids, impregnation and water loss. Firmness, kinetic coefficients and color were determined for each treatment. Ultrasound increased the uptake of solutes (p < 0.05) with the exception of calcium, sodium ions, and acidity, where diffusion coefficients did not significantly differ among treatments. Loss of water, total and soluble solids in tissue significantly increased at 55 °C with 47 kHz, with diffusion coefficients of 13.23 × 10⁻¹⁰ m²/s, 7.26 × 10⁻¹⁰ m²/s and 14.42 × 10⁻¹⁰ m²/s, respectively. These increases may be attributed to increased cell wall permeability, facilitating transport of water and solute, as evidenced by product firmness, where ultrasound treatments had a negative effect on firmness.     

Supercritical fluid extraction of black pepper oil

The supercritical fluid extraction (SFE) of oil from ground black pepper, using supercritical carbon dioxide (SC CO₂) as a solvent, is presented in this study. The effect of process parameters, namely pressure (90, 100, 150 bar) and temperature (40, 50 °C) of extraction, and solvent flow rate (1.1, 2, 3 kg/h), on the extraction rate was examined in a series of experiments conducted in a bench scale apparatus. The results indicated a significant increase of extraction rate with increase of pressure or decrease of temperature. A similar effect was observed with the increase of solvent flow rate. The experimental data were satisfactorily correlated by two mass balance models. The first one is based on the Lack’s plug flow model, which accounts for both the solubility and diffusion controlled regimes of the extraction, and the second one on the adsorption–desorption equilibrium of solute from solid tissue, the diffusion of the solute dissolved in the supercritical solvent to the surface and the mass transfer through the external film into the bulk.     

Calculation process for the recovery of solutes retained in the ice in a multi-plate freeze concentrator: Time and concentration

Fractionated thawing was studied as a method to recover solutes incorporated in the ice obtained in a cryoconcentrator. Thawing times and solute concentration in the ice were determined at several thawing temperatures.Ice sheets used for the thawing studies were obtained by cryoconcentrated solutions of sugars and simulated juice at initial concentrations of 5 to 20 °Brix. The ice sheets produced contained levels of solutes between 1.0 and 9.0 °Brix.Fractionated thawing was performed at temperatures of 20 to 30 °C while maintaining geometrical similarity for the test samples. By fractionated thawing more than 60% of the solutes retained in the ice was recovered in 34%, of the total thawing time.The procedure presented allows the determination of the solute concentration achieved in the various thawing fractions and predicts the thawing time required for a given form factor, melting temperature and the solute mass fraction in the ice.Industrial relevanceThe freeze concentration is a technology that allows eliminating water from liquid foods at temperatures below the water's freezing point, which allows obtaining products of better quality. Fractionated thawing was studied as a method to recover solutes incorporated in the ice, improving the global efficiency of a freeze concentration process by optimal recovery of the solutes retained in the ice. It also provides estimations of the energy used for thawing. This work continues the research in falling film freeze concentration technology which we have submitted and published in this journal. This work contributes to increase the global process efficiency.     

Pilot scale production of a phospholipid-enriched dairy ingredient by means of an optimised integrated process employing enzymatic hydrolysis,ultrafiltration and super-critical fluid extraction

Pilot scale production of a dairy ingredient enriched in phospholipids (PLs) was generated from a buttermilk powder (BMP) substrate utilising a combined process of targeted enzymatic hydrolysis of the innate milk proteins followed by ultrafiltration with a 50 kDa membrane. An 8.5 fold increase in PL was achieved in the 50 kDa retentate (50 R) compared to the BMP, 11.05 ± 0.02% and 1.30 ± 0.00% total PL, respectively. Simultaneously, total lipid content in the retentate increased 8.7 fold with reference to the BMP, 60.07 ± 0.54% and 6.84 ± 0.17% total lipid respectively. Protein reduced to 10.58 ± 0.09% (50 R) from 31.40 ± 0.57% in BMP. Supercritical CO₂ fluid extraction (SFE) was employed to generate a purified lipid fraction. SFE with ethanol as a co-solvent yielded a purified lipid extract with enriched PLs level of 56.24 ± 0.07% on a dry matter basis.Industrial relevancePLs have many associated health and nutritional benefits including those related to cognitive development and repair. Generation of an ingredient enriched in dairy PLs would be advantageous from an industrial view to allow fortification of nutritionals, both infant and geriatric, in promoting brain health. The present work demonstrates a novel pilot scale process for the generation of a PL enriched ingredient from a BMP substrate. Utilising a combined process of targeted protein hydrolysis followed by selective removal by ultrafiltration of the smaller molecular weight peptide material, an ingredient with 8.5 fold increase in PL material was achieved. SFE technology was utilised to generate a purified lipid extract with greater PL levels for future applications in biological assays to determine these pathways. The need for investigate and further develop the knowledge relating to the modes of action of these bioactive compounds would be beneficial from a nutritional perspective.     

Inhibition of Chymosin and the Coagulation of Para-Casein Micelles by Anions

The effect of monovalent anions on the coagulation of para-casein micelles was determined by monitoring light transmission after adding different Ca salts (40 mM) to partially hydrolyzed casein micelles. The release of macro-peptide by chymosin was quantified using fluorescamine. The average rate of the chymosin-initiated coagulation of casein micelles, approximated by the reciprocal of clotting time, was determined as a function of anion type and concentration to determine the simultaneous effects of anions on chymosin velocity and para-casein micelle aggregability.Chymosin velocity and the coagulation of para-casein micelles were progressively inhibited by anions; the larger the anion, the greater the inhibition (SCN⁻ > NO₃⁻ > Br⁻ > Cl⁻). This is attributed to the binding of anions to cationic binding sites on kappa-casein and para-kappa-casein. The relative effect of the larger anions compared with that of Cl⁻ on the average rate of the chymosin-initiated coagulation of casein micelles increased with anion concentration (6 to 120 mM) but became limited at 120 mM. In the presence of 120 mM SCN⁻, NO₃⁻ and Br⁻, the average rate of coagulation was 26, 59, and 78% of that obtained with 120 mM Cl⁻.The marked sensitivity of the interactions between chymosin and kappa-casein and between para-casein micelles to anion type support conclusions that cationic sites on kappa-casein are important in the mechanism of the chymosin-initiated coagulation of casein micelles. Thus, monovalent anions may be useful to elucidate the mechanism of protein-protein interactions in food systems.     

An economic assessment of proteins recovery from fish meal effluents by ultrafiltration

The main objective of this work was to assess the technical and economical feasibility of proteins recovery from fish meal effluents using crossflow membrane technology, namely, ultrafiltration (UF) and nanofiltration (NF).Mackerel processing effluents were pre-treated by microfiltration (MF cartridges battery of 80, 20 and 5 μm pore size) followed by UF (membrane Carbosep M2, 15 kDa MWCO) or NF (membrane Kerasep NanoN01A, 1 kDa MWCO). A suitable treatment for the fish meal effluents consisted of a MF pre-treatment followed by UF operating at 4 bar, 4 m/s, natural pH and ambient temperature. UF yielded an average permeation flux of 28 l/(m² h),¹ and 62% proteins rejection for a volume reduction factor of 2.3. Both membranes fully recovered their original permeabilities through an acidic/basic washing cycle. The economic assessment of proteins recovery from fish meal effluents by UF was accomplished for a production of 544 ton/yr of fish meal (66% protein content), yielding a net present worth of 160×10³ US$, interest rate of return of 17% and payback time of 8 years.     

Production of chitin oligosaccharides with different molecular weights and their antioxidant effect in RAW 264.7 cells

The purpose of this research is not only to produce two kinds of chitin oligosaccharides or N-acetyl chito-oligosaccharides (NA-COSs) with different molecular weights (MW) from crab chitin hydrolysis solution but also to determine their effect against oxidative stress in live cells. Two kinds of NA-COSs with MW 1–3 kDa (NA-COS 1–3 kDa) and below 1 kDa (NA-COS < 1 kDa) were obtained using an ultrafiltration membrane system. They exhibited an inhibitory effect against DNA and protein oxidation. In addition, in their presence, intracellular glutathione (GSH) level and direct intracellular radical scavenging effect were significantly increased in a time-dependent manner in mouse macrophages (RAW 264.7) and rendered inhibitory effect against cellular oxidative stress. In particular, NA-COS 1–3 kDa was more effective than NA-COS < 1 kDa in protein oxidation and production of intracellular free radicals in live cells. These results suggest that NA-COSs act as a potential scavenger against oxidative stress in cells.     

Combined effect of γ-irradiation and osmotic pretreatment on mass transfer during dehydration

The combined effect of γ-irradiation (3.0–9.0 kGy) and osmotic pretreatment (10 and 50°B) on dehydration kinetics was studied. The exposure to irradiation pretreatment resulted in an increase in cell wall permeabilization, leading to softening of tissue, which in turn resulted in faster dehydration. The effective diffusion coefficient of water in case of potato during dehydration, considering Fickian diffusion, increased from 2.38 × 10⁻⁹ to 4.14 × 10⁻⁹ m²/s at 9.0 kGy, whereas the osmotic pretreatment resulted in lower dehydration rates due to infusion of solute from osmotic solution, which resulted in lower mass transfer rates. Even though the effective diffusion coefficients decreased from 2.38 × 10⁻⁹ to 1.55 × 10⁻⁹ m²/s (up to 50°B), the osmotic pretreatment improves nutritional, sensorial and functional properties of food without changing its integrity, apart from partial removal of water present in food. The combining of γ-irradiation treatment with osmotic pretreatment resulted in increased mass transfer rates during air dehydration, offering a feasible solution for satisfactorily enhancing the mass transfer rates.     

Heat-induced Maillard reaction of the tripeptide IPP and ribose: Structural characterization and implication on bioactivity

Maillard reaction products (MRPs) were prepared from aqueous model mixtures containing 60 g L^? 1 ribose and 30 g L^? 1 of the bioactive tripeptide IPP (Ile-Pro-Pro), heated at 98 °C. MRP and associated reactions with changes in IPP were observed within one hour of heat-treatment. The pH of MRPs decreased significantly during the heat treatment of IPP–ribose mixtures from 9.0 to 7.6 after one hour. The amino group content, IPP and ribose concentration decreased significantly during heat treatment. The fluorescence intensity of the IPP–ribose MRPs reached the maximum within 2 h. Modification of the UV/vis spectra for IPP–ribose MRPs was mainly due to a condensation reaction of IPP with ribose. Compounds with molecular weight between 300 and 650 Da were dominant while compounds smaller than 250 Da were also produced during the reactions, as characterized by size exclusion chromatography. Mass spectrometry revealed that IPP was conjugated to ribose at the N-terminal (m/z of 458.3) upon heat-treatment. The presence of ribose also promoted peptide degradation to dehydrated IP (m/z of 211.1). IPP–ribose MRPs lost the known angiotensin-I-converting enzyme (ACE) inhibitory activity of IPP; however, strong antioxidant properties were detected.     

Functional properties and Angiotensin-I converting enzyme inhibitory activity of soy–whey proteins and fractions

Soy proteins when prepared to high purity can confer good functional properties and the whey by-product is a potential source for bioactivity. In this study, we determined the protein, moisture, fiber, solubility, foaming, emulsion properties, as well as Angiotensin-I converting enzyme (ACE-I) inhibitory activity of prepared soy–whey proteins and its fractions. The soy–whey proteins were fractionated into < 5, > 5, > 10, and > 50 kDa using ultrafiltration. The expanded AACC methods were used to determine protein, moisture, and fiber analyses of the whey and its fractions. Solubility method was conducted to determine the protein solubility profile of the soy–whey and its fractions at varying pHs. Turbidimetric method was used to evaluate emulsifying activity (EA) and emulsion stability (ES). There were significant differences observed in moisture, protein and salt contents between unfractionated, > 50 kDa and smaller sized fractions. No significant differences were observed with phytic acid and total dietary fiber contents among all samples. The unfractionated whey protein and > 50 kDa fraction showed better solubility than other fractions. Unfractionated whey protein had the highest foam capacity (42.7 mL) while the fraction > 5 kDa showed the greatest foaming stability (46 min). The highest emulsion activity (0.33 ± 0.1) and stability (825.1 ± 45.1) was obtained with the > 50 kDa fraction while the unfractionated whey protein had the highest ACE-I inhibition activity. The findings indicate that soy–whey protein fraction (> 50 kDa) had good solubility, emulsion activity and stability, while the unfractionated whey protein exhibited the strongest ACE-I inhibition percentage (19%).     

Antioxidant activities of enzymatic rapeseed protein hydrolysates and the membrane ultrafiltration fractions

In this study, rapeseed protein isolate was hydrolyzed with various proteases to obtain hydrolysates that were separated by membrane ultrafiltration into four molecular size fractions (<1, 1–3, 3–5, and 5–10 kDa). Alcalase hydrolysis significantly (p < 0.05) produced the highest yield of protein hydrolysate while Flavourzyme produced the least. The <1 kDa fraction was the most abundant after the membrane ultrafiltration of the protein hydrolysates, which indicates that the proteases were efficient at reducing the native rapeseed proteins into low molecular weight peptides. Antioxidant properties of the resulting hydrolysates and membrane fractions were characterized and results showed the Pepsin + Pancreatin (P + P) protein hydrolysate had significantly highest (p < 0.05) scavenging activity against DPPH radical among the unfractionated enzymatic hydrolysates. But the P + P hydrolysate was not as effective as other hydrolysates during long-term inhibition of linoleic acid oxidation. For most of the samples, fractionation into the <1 kDa peptides significantly (p < 0.05) improved DPPH and superoxide scavenging properties when compared to the unfractionated protein hydrolysates. Only the <1 kDa fraction showed ferric reducing antioxidant power and the effect was dose-dependent. Overall, Alcalase and Proteinase K seem to be more efficient proteases to release antioxidant peptides from rapeseed proteins when compared to P + P, Flavourzyme and Thermolysin.     

A review of process simulations and the use of additives in spray drying

The driving forces for protein migration during drying have been reviewed and existing simulations on drying process have been analysed. Current models of spray drying have not captured the diffusion process of both the solvent and solutes, or the effects of the solubilities and surface activities of the components. A new distributed-parameter, multicomponent model needs to be developed. Casein has been examined and found to coat spray-dried particles at 1 w/w%, significantly lower than other additives, such as maltodextrin, which commonly make up between 10 w/w% and 20 w/w% of the total solids. The efficacy of casein as a spray-drying additive thus needs to be studied.     

Conjugated linoleic acid (CLA) concentration,fatty acid composition and cholesterol content of some Turkish dairy products

Conjugated linoleic acid (CLA) concentrations, fatty acid composition and cholesterol content of some Turkish dairy products (butter, processed cheese, Kaymak and cream) were determined by capillary gas chromatography. The CLA and cholesterol content of some Turkish dairy products ranged from 1.50–5.60 mg/g fat and 148.30–369.04 mg/g fat, respectively. The most abundant saturated fatty acids in the dairy products investigated were palmitic acid (C16:0), stearic acid (C18:0) and myristic acid (C14:0). In all dairy products, C18:1 cis-9, 12 unsaturated fatty acid content (23.12–32.78 g/100 g) was considerably higher than others. In all samples studied, there was no correlation between CLA content of products and the linoleic acid content, or any other unsaturated fatty acid. A positive correlation between cholesterol and fat content of dairy products was observed.     

Determination,analysis and prediction of the volumetric behavior of milk at high pressure

High pressure preservation technologies are consolidating in the food industry as an interesting alternative to traditional thermal processes. Process modeling contributes to its progress and requires the input of food properties like density for calculations. The dependency on pressure of these properties is indispensable but it is rarely available in the literature. The sector of dairy products is an important target for the development of novel foods by high pressure treatments (both high hydrostatic pressure processing and ultra-high pressure homogenization). Thus, the main objective of this research was to characterize the volumetric properties of raw whole milk and skim milk. A variable-volume piezometer with a solid-piston volumeter was employed for this purpose. Density, specific volume, isothermal compressibility and thermal expansion coefficient were determined between 0 and 60 °C under pressures up to 350 MPa; at atmospheric pressure, measurements cover temperatures up to 90 °C. Results show that milk solutes and fats, although present in low quantities in milk compared to water, have an influence which is worthy of consideration on milk volumetric properties. Irregularities appear from 200 MPa in the dependencies on temperature of the studied milk properties. From a composition-based model, it is highlighted that milk solutes' specific volume behavior is inverted around 55 °C and that milk fats' compressibility goes through a maximum around 30 °C. The composition-based model is further developped for the calculation of milk properties as a function of pressure at different temperatures; prediction errors are below 2%. Useful data and equations for high pressure processing simulation are provided together with an original view on the combined effects of pressure and temperature on milk solutes and fats.     

Cheese made from instant infusion pasteurized milk: Rennet coagulation,cheese composition,texture and ripening

Milk subjected to instant infusion pasteurization (IIP) at 72 °C, 100 °C and 120 °C (holding time 0.2 s) exhibited increased rennet coagulation time and decreased curd firming rate for increasing heat treatment temperature, when compared with raw or high temperature short time pasteurized (HTST) milk. However, addition of 4.5 mm or 9.0 mm of calcium restored the impaired rennet coagulation ability. Open texture cheeses produced from IIP milk (100 °C and 120 °C) contained significantly more moisture, had lower pH and shorter texture than similar cheese from IIP at 72 °C and HTST pasteurized milk. Cheese ripening was also affected by heat treatment, and different patterns of casein breakdown and peptide formation resulted from cheeses made from milk treated to IIP at 100 °C and 120 °C compared with cheeses made using IIP at 72 °C or HTST.     

Muscle and meat quality characteristics of Holstein and Salers cull cows

Muscle characteristics and sensory rating of meat were determined in M. longissimus thoracis (LT), M. semimembranosus (SM), M. semitendinosus (ST) and M. triceps brachii (TB) from seven Holstein (HO, dairy breed) and six Salers (SA, beef breed) cull cows slaughtered at 6–7 years of age at the same fat score. Significant differences (P < 0.001) among muscle types were observed: ST was the more glycolytic and TB the more oxidative; total collagen: ST > SM = TB > LT; initial and overall tenderness: LT > TB = SM > ST, juiciness: TB > LT = SM > ST. Flavour differed only between breeds: HO > SA (P < 0.01). Three tenderness classes (high, intermediate, low) were determined from scores for sensory overall tenderness for all 52 meats: the lower total and insoluble collagen contents, the more oxidative metabolism, the more tender was the meat. Muscle type, and not breed explained most of the variability of meat quality from dairy and beef cull cows slaughtered at the same age and fat score.     

Short-term appetite-reducing effects of a low-fat dairy product enriched with protein and fibre

The objectives of this work were to investigate short-term appetite-reducing effects of an innovative low-fat yogurt enriched with protein (8 g/serving) and fibre (2.6–2.9 g/serving). Two studies were conducted using randomised cross-over designs. Healthy women consumed a mid-morning snack consisting of either the test or the control yogurt product (Study 1, n = 24: iso-energetic, not iso-weight conditions; Study 2, n = 121: iso-weight, not iso-energetic conditions) under laboratory conditions. Subjective appetite ratings (of hunger, fullness, desire to eat and prospective consumption) were recorded throughout the morning; sensory and hedonic ratings were also collected. In Study 2, two hours after consumption of the dairy snack, subsequent food intake at lunch was also measured. The test product reduced subjective appetite compared to the control (all ratings, P < 0.05). Energy intake at lunch was reduced by 274 kJ after the test compared to the control (P < 0.001). These two studies demonstrated that a low-fat dairy product enriched with protein and fibre can significantly reduce short-term appetite.     

Effects of controlled pepsin hydrolysis on antioxidant potential and fractional changes of chickpea proteins

This study investigated the effects of controlled pepsin hydrolysis on antioxidant potential and fractional changes of chickpea protein extracts (CPE). The enzyme hydrolysis increased soluble protein content (1.2 to 2-fold) and free radical scavenging activity (1.9 to 3-fold) of hydrolyzed chickpea protein extract (HCPE), but almost unaffected its antioxidant potential in oil-in-water emulsion system and reduced its iron chelating capacity (1.3-fold) and functional properties. The chromatographic fractions of CPE are mainly acidic, while those of HCPE are mainly basic and neutral. The majority of chickpea proteins had pI between 4.5 and 5.5, and molecular weight (MW) between 15 and 40 kDa, while MW of their pepsin hydrolysis products ranged between 6.5 and 14.2 kDa. The main antioxidant proteins in CPE and HCPE fractionated by ultrafiltration had MW greater than 30 kDa and between 2 and 10 kDa, respectively. The chickpea proteins and hydrolysates showed different potentials as functional food ingredients.     

Estimation of the diffusivities of sodium chloride,potassium sorbate and sodium bisulphite in mango slices processed by hurdle technology

The fractional amount of sodium chloride, potassium sorbate and sodium bisulphite were evaluated in mango slices immersed in limited volumes of syrup at 25, 50 and 70 °C. The syrup contained 250 g sucrose, 1.5 g sodium chloride, 0.5 g potassium sorbate and 0.25 g sodium bisulphate per kilogram of solution. The sodium chloride concentration in the syrup was confirmed with a flame photometer, and the concentrations of potassium sorbate and sodium bisulphite were determined using high-performance liquid chromatography (HPLC). Fick’s second law was used to calculate effective diffusion coefficients and to predict solute content in the mango slices. Diffusion coefficients were affected by temperature and were correlated by the Arrhenius equation. The experimental data fit the proposed mathematical model well, allowing prediction of the system’s behavior at different temperatures. The resultant diffusivities ranges were 2.63–3.54 × 10^?9 m²/s for sodium chloride, 3.88 × 10^?9–8.3 × 10^?10 m²/s for potassium sorbate and 1.83 × 10^?7–5.98 × 10^-8 m²/s for sodium bisulphite.     

Cocoa brew inhibits in vitro α-glucosidase activity: The role of polyphenols and high molecular weight compounds

Cocoa brew showed a dose-dependent inhibitory activity against α-glucosidase (IC₅₀ 7.87 mg/mL). The cocoa brew was fractionated by ultrafiltration in a low molecular weight fraction (LMW < 10 kDa) and two melanoidin-rich fractions called high molecular weight (HMW > 30 kDa) and intermediate molecular weight (IMW 10–30 kDa) fractions. All fractions tested caused some inhibition with IMW that was the most active (IC₅₀ 2.37 mg/mL). LMW fraction was separated with Sephadex LH-20 in an unbound (containing monomeric and dimeric catechins) and a bound fraction. All the inhibitory activity was recovered in the unbound fraction. All the phenolic compounds identified with HPLC showed α-glucosidase inhibitory activity. IMW and HMW fractions were fractionated by ethanol precipitation. The fractions from IMW precipitated with 75 and 25% ethanol were found to contain power inhibitors of α-glucosidase activity (IC₅₀ 0.87 and 1.01 mg/mL, respectively). In the HMW sample, the fractions precipitated with 50 and 75% ethanol were found to be active against α-glucosidase activity. Most of the inhibitory activity against α-glucosidase of cocoa brew was due to the LMW fraction (56%) whereas IMW and HMW contributed for about 47% of the inhibitory activity. This study suggests that different components of cocoa may influence α-glucosidase activity.