Showing papers in "Food and Bioprocess Technology in 2010"

Supercritical Fluid Extraction of Bioactive Compounds: Fundamentals, Applications and Economic Perspectives

Abstract: This review provides an updated overview of the most important applications of supercritical fluids in the extraction of bioactive compounds from plant matrices The main factors influencing the extraction yields, solubility, and manufacturing costs are described Aspects concerning the operational processing in the extraction and fractionation are also discussed The data compiled herein are focused on the extraction of essential oils, phenolic compounds, carotenoids, tocopherols, and tocotrienols

A Review on Microbial Lipases Production

Abstract: This review paper provides an overview regarding the main aspects of microbial lipases production. The most important microbial lipase-producing strains for submerged and solid-state fermentations are reviewed as well as the main substrates, including the use of agroindustrial residues. Current process techniques (batch, repeated-batch, fed-batch, and continuous mode) are discussed and the main bioreactors configurations are also presented. Furthermore, the present review paper shows a general overview about the development of mathematical models applied to lipase production. Finally, some future perspectives on lipase production are discussed with special emphasis on lipase engineering and the use of mathematical models as a useful tool for process improvement and control.

Non-uniform Temperature Distribution During Microwave Heating of Food Materials—A Review

Abstract: Use of microwaves has increased largely in the domestic household in the last few decades due to the convenience of using microwave ovens. In the industrial sector, microwave processing is used in some of the unit operations, while it is yet to capture a major place in the industrial applications. The major drawback associated with microwave heating is the non-uniform temperature distribution, resulting in hot and cold spots in the heated product. The non-uniform temperature distribution not only affects the quality of the food but also raises the issue of food safety when the microorganisms may not be destroyed in the cold spots. The temperature distribution during microwave heating has been studied in a wide variety of products by several researchers. This paper summarizes their results and the solutions offered by them to lessen the non-uniformity of heating. The current applications of microwave energy in the industrial sector are also highlighted.

Pulsed Light Treatments for Food Preservation. A Review

Abstract: Consumers demand high-quality processed foods with minimal changes in nutritional and sensory properties. Nonthermal methods are considered to keep food quality attributes better than traditional thermal processing. Pulsed light (PL) is an emerging nonthermal technology for decontamination of food surfaces and food packages, consisting of short time high-peak pulses of broad spectrum white light. It is considered an alternative to continuous ultraviolet light treatments for solid and liquid foods. This paper provides a general review of the principles, mechanisms of microbial inactivation, and applications of PL treatments on foods. Critical process parameters that are needed to be optimized for a better efficiency of PL treatments are also discussed. PL has considerable potential to be implemented in the food industry. However, technological problems need to be solved in order to avoid food overheating as well as to achieve better penetration and treatment homogeneity. In addition, a more extensive research is needed to understand how PL affects quality food attributes.

Drying Technology: Trends and Applications in Postharvest Processing

Abstract: Thermal drying technologies have attracted significant RD conventional hot air drying can be detrimental to the retention of bioactive ingredients. High temperature tends to damage and denature the product, destroy active ingredients, cause case hardening and discoloration, etc. This article briefly summarizes some of the emerging drying methods and selected recent developments applicable to postharvest processing. These include: heat pump-assisted drying with multimode and time-varying heat input, low and atmospheric pressure superheated steam drying, modified atmosphere drying, intermittent batch drying, osmotic pretreatments, microwave-vacuum drying, etc.

Influence of Gluten-free Flours and their Mixtures on Batter Properties and Bread Quality

Abstract: Gluten is a major component of some cereals and is responsible for flour technological characteristics to make bakery products. However, gluten must be eliminated from the diet of celiac patients because its ingestion causes serious intestinal damage. The objectives of this study were to assess the effect of different flours and their mixtures on thermal and pasting properties of batters, and to study the quality parameters and staling rate of gluten-free breads. Starch gelatinization temperatures and enthalpies depended on batter composition. Soy flour addition had a higher effect on rice than on corn starch, indicating some differential interaction between starch and proteins. Inactive soy flour incorporation improved all bread quality parameters in both corn- and rice-based breads. Higher batter firmness of formulations with soy addition (extrusion force was doubled in rice/soy and rice/corn/soy batters with regard to rice and rice/corn batters) partially explained higher specific volume (rice breads: 1.98 cm3/g; rice/soy 90:10 2.51 cm3/g, corn/soy 90:10: 2.05 cm3/g, whereas corn/soy 80:20: 2.12 cm3/g), as these batters retained more air during proofing. The staling rate was decreased by soy flour incorporation on rice (staling rate of rice breads with 10% soy diminished 52%, and with 20% of soy addition, 77%, both regarding to 100% rice breads) and corn formulation (the staling rate of corn/soy 80:20 breads was 5.9% lower than corn/soy 90:10) because of the high water-holding capacity of soy proteins and the interactions established with amylopectin that could retard the retrogradation process. Breads made with rice, corn, and soy flours showed the best quality attributes: high volume, good crumb appearance, soft texture, and low staling rate.

Microscopic and Spectroscopic Evaluation of Inactivation of Staphylococcus aureus by Pulsed UV Light and Infrared Heating

Abstract: Pulsed UV light and infrared heat-treated Staphylococcus aureus cells were analyzed using transmission electron microscopy to identify the cell damage due to the treatment process. A 5-s treatment with pulsed UV light resulted in complete inactivation of S. aureus even after enrichment. The temperature increase during the pulsed UV light treatment was insignificant, which suggested a nonthermal treatment. S. aureus was also infrared heat treated using an infrared heating system with six infrared lamps. Five milliliters of S. aureus cells in phosphate buffer was treated at 700°C lamp temperature for 20 min. The microscopic observation clearly indicated that there was cell wall damage, cytoplasmic membrane shrinkage, cellular content leakage, and mesosome disintegration after both pulsed UV light and infrared treatments. Fourier transform infrared microspectrometry was successfully used to classify the pulsed UV light and infrared heat-treated S. aureus by discriminant analysis.

Color of Salmon Fillets By Computer Vision and Sensory Panel

Abstract: A computer vision method was developed and used to assign color score in salmon fillet according to SalmonFan™ card The methodology was based on the transformation of RGB to L*a*b* color space In the algorithm, RGB values assigned directly to each pixel by the camera in the salmon fillet image, were transformed to L*a*b* values, and then matched with other L*a*b* values that represent a SalmonFan score (between 20 and 34) Colors were measured by a computer vision system (CVS) and a sensorial panel (eight panelists) under the same illumination conditions in ten independent sets of experiments Errors from transformation of RGB to L*a*b* values by the CVS were 27%, 1%, and 17%, respectively, with a general error range of 183% The coefficient of correlation between the SalmonFan score assigned by computer vision and the sensory panel was 095 Statistical analysis using t test was performed and showed that there were no differences in the measurements of the SalmonFan score between both methods (t c = 165 ≤ t = 196 at α = 005%) The methodology presented in this paper is very versatile and can potentially be used by computer-based vision systems in order to qualify salmon fillets based on color according to the SalmonFan card

Production and Characterization of an Antifungal Compound (3-Phenyllactic Acid) Produced by Lactobacillus plantarum Strain

Abstract: The Lactobacillus plantarum strain was isolated from grass silage that produces a broad spectrum of antifungal compound, active against food and feed-borne filamentous fungi in agar plate assay. Aspergillus fumigatus and Rhizopus stolonifer were the most sensitive among molds. No inhibitory activity could be detected against mold Penicillium roqueforti. Enhanced antifungal activity was observed at 30 °C in pH 6.5. Minimum inhibitory concentration values against fungal cultures were ranged from 6.5 to 12.0 mg/ml for commercial 3-phenyllactic acid. The production of antifungal compound phenyllactic acid (PLA), lactic acid, and acetic acid by L. plantarum strain was also investigated. Structure characterization of the antifungal compound was carried out by nuclear magnetic resonance spectroscopy, infrared spectroscopy, and gas chromatography. The produced compound (PLA) acted as a fungistatic and delayed the growth of a variety of fungal contaminants.

Use of High-Intensity Ultrasound and UV-C Light to Inactivate Some Microorganisms in Fruit Juices

Abstract: Novel technologies that involve non-thermal processes have been investigated in the last two decades as full or partial alternatives to conventional heat treatment. The main objective of this study was to evaluate the survival of single or strain cocktail of Escherichia coli, Saccharomyces cerevisiae, and a yeast cocktail in orange (pH 3.5; 9° Brix) and/or apple (pH 3.1; 12° Brix) juices and in 0.1% w/w peptone water processed by two non-thermal techniques: high-intensity ultrasound (USc) and/or short-wave ultraviolet radiation (UV-C). USc treatments (20 kHz, 95 µm-wave amplitude) were performed using a stainless steel continuous flow cell with a 13-mm probe (0.2 L/min; 40°C). The UV-C device consisted of a 90-cm long UV-C-lamp (100 W) placed inside a glass tube leaving an annular flow space (0.2 L/min; 40°C). Inoculated systems were recirculated through simultaneous or consecutive USc and UV-C devices and samples were taken at preset time intervals. Microbial populations were monitored by plate count technique. In peptone water and apple juice, UV-C radiation provoked higher E. coli ATCC 35218 inactivation than USc treatment. E. coli ATCC 35218 and its cocktail were more sensitive than S. cerevisiae KE162 and the cocktail of yeasts. UV-C efficiency was highly dependent on media nature. The poor single effect of UV-C light in orange juice was enhanced by the combination with USc. Combined treatment was more effective in simultaneous rather than in a series of USc − UV-C arrangement.

Effect of Air Temperature on Drying Kinetics, Vitamin C, Antioxidant Activity, Total Phenolic Content, Non-enzymatic Browning and Firmness of Blueberries Variety O´Neil

Abstract: Effect of air temperature on drying kinetics, vitamin C, antioxidant capacity, total phenolic content (TPC), colour due to non-enzymatic browning (NEB) and firmness during drying of blueberries was studied. Drying curves were satisfactorily simulated with the Weibull model at 50, 60, 70, 80 and 90°C. The scale parameter (β) decreased as air temperature increased and an activation energy value of 57.85 kJ mol−1 was found. Important losses of vitamin C were reported during drying for all the working temperatures (p < 0.05). Although TPC decreased as air-drying temperature increased (p < 0.05) in comparison to its initial value, the dehydration at high temperatures (e.g., 90°C) presented high values for these antioxidant components. Discoloration due to NEB reaction was observed at all the working temperatures showing a maximum value at 90°C (p < 0.05). The radical scavenging activity showed higher antioxidant activity at high temperatures (80 and 90°C) than at low temperatures (50, 60 and 70°C) (p < 0.05). A tissue firmness reduction was observed with increasing temperature (p < 0.05).

Emerging Bacterial Pathogens in Meat and Poultry: An Overview

Abstract: Many foodborne diseases are associated with consumption of meat and poultry. Some pathogens were not previously known (new pathogens), others have newly arisen as foodborne (emerging pathogens), and others have become more potent or associated with other products (evolving pathogens). Many of these pathogens may cause severe illness, besides gastroenteritis. Campylobacter jejuni is a leading cause of food-associated bacterial illness; Campylobacter jejuni O:19 and other serotypes are common etiological agents of Guillain–Barre syndrome, a neuropathy due to autoimmune response. Salmonella Typhimurium DT104 and other serotypes have been found to be multi-drug resistant; salmonellosis may lead to chronic reactive arthritis. Many outbreaks of enterohemorrhagic Escherichia coli have been associated with consumption of undercooked contaminated ground beef; complication may occur (e.g., hemolytic uremic syndrome and thrombotic thrombocytopenic purpura). Listeria monocytogenes is ubiquitous; listeriosis is of major public health concern because of the severity and non-enteric nature of the disease (meningitis or meningoencephalitis, septicemia, and abortion) and its ability to multiply at refrigeration temperature. Arcobacter butzleri is a potential foodborne pathogen, and has been isolated from raw poultry, meat, and meat products; but its role in causing human illness is not fully understood. Mycobacterium avium subsp. paratuberculosis can be transmitted by ingestion of raw and processed meats; the organism may contribute to Crohn’s disease, a chronic intestinal enteritis. Beef, pork, lamb, and/or poultry have been reported as sources of infection for the abovementioned organisms but have not been generally associated with disease outbreaks of some of the pathogens.

Resistance of Microencapsulated Lactobacillus acidophilus LA1 to Processing Treatments and Simulated Gut Conditions

Abstract: This investigation reports the effect of microencapsulation using sodium alginate and starch on the tolerance of probiotic Lactobacillus acidophilus LA1 to selected processing conditions and simulated gastrointestinal environments. The organism survived better in the protected form at high temperatures (72, 85, and 90 °C) and at high salt concentrations (1%, 1.5%, and 2%). The free cells were completely destroyed at 90 °C whereas the microencapsulated cells reduced by 4.14 log cycles. The log cycle reduction was 5.67 and 2.30, respectively, in free and protected cells when incubated for 3 h with 2% (w/v) NaCl. Homogenization did not affect the viability of the cells but led to the disruption of the protective encapsulating material around the cells. Microencapsulation provided better protection at simulated conditions of gastric pH (1.0, 1.5, and 2.0) and at high bile salt concentrations (1.0%, 1.5%, and 2.0%). The free and protected cells registered 5.47 and 2.16 log cycle reduction, respectively, after 3-h incubation at 2% bile salt (w/v). The release of the microencapsulated organisms in simulated colonic pH required 2.5 h. These studies demonstrated that microencapsulation of probiotic L. acidophilus LA1 in sodium alginate is an effective technique of protection against extreme processing conditions and under simulated gastrointestinal environment.

Effect of Processing Methods on the In Vitro Protein Digestibility and Vitamin Content of Edible Winged Termite (Macrotermes subhylanus) and Grasshopper (Ruspolia differens)

Abstract: The influence of processing methods of toasting and solar drying on the in vitro protein digestibility and vitamins content of edible winged termites, green grasshoppers, and brown grasshoppers consumed in Siaya, district of Kenya, was determined using standard methods. Analysis was done on fresh, toasted, toasted dried, and fresh dried insect samples. There was no significant change (p > 0.05) in protein digestibility in the termite samples, while a significant decrease (p ≤ 0.05) in the grasshopper samples was observed on toasting and drying. There was a significant reduction (p ≤ 0.05) in riboflavin content with 4.18 mg/100 g in fresh termites, 2.76 mg/100 g in toasted termites, 2.26 mg/100 g in fresh dried termites, and 1.50 mg/100 g in toasted dried termites on processing. There was also a significant reduction (p ≤ 0.05) in niacin content in the grasshoppers with 3.61 mg/100 g in fresh green grasshopper, 3.28 mg/100 g in toasted green grasshopper, 3.22 mg/100 g in fresh dried green grasshoppers, and 3.06 mg/100 g in toasted dried green grasshoppers. A significant reduction (p ≤ 0.05) in retinol content with 2.24 μg/g in fresh termites, 1.56 μg/g in toasted termites, 1.02 μg/g in toasted dried termites, and 0.98 μg/g in fresh dried termites was also reported. The processing methods of the insects affected their nutrient potential as evidenced by the changes in protein digestibility and vitamins content. Therefore, optimal processing methods need to be investigated even as we promote commercialization of these insects.

Maize-Based Gluten-Free Bread: Influence of Processing Parameters on Sensory and Instrumental Quality

Abstract: The performance of maize bread with spongy texture is still a technological challenge due to the absence of a natural network required for holding the carbon dioxide released during the fermentation process. The objective of this research was to investigate the influence of different maize varieties (regional and hybrid), milling process (electric and water mill), formulation and processing variables on the sensory and instrumental (specific volume, texture and colour) quality attributes of corn bread. For that purpose, the traditional breadmaking process applied to the development of the ethnic Portuguese bread (broa) obtained from composite maize–rye–wheat flour was modified to produce gluten-free broa. Significant differences (P < 0.05) between regional and hybrid maize were detected in terms of protein, amylose, and maximum, minimum and final viscosities as evaluated by Rapid Visco Analyser. Concerning the effect of milling process, the grinding in a water mill occurs at slower rate than it does in the electrical mill, in consequence the flour from water milling had lower ash content and higher maximum, minimum and final viscosities than the one obtained from electrical milling. An important point in the breadmaking process was the flour blanching that resulted in doughs with higher consistency, adhesiveness, springiness and stickiness as measured by texture analyser, due to the partial gelatinisation of the corn starch. Baking assays demonstrated sensory preference for regional in detriment of hybrid maize varieties for traditional broa production. Breadmaking technology could be satisfactorily applied to produce gluten-free broa.

Production of Cellulases through Solid State Fermentation Using Kinnow Pulp as a Major Substrate

Abstract: A study was conducted to appraise the potential of using kinnow pulp for production of cellulases by Trichoderma reesei Rut C-30. Out of the different combinations tried out, dried kinnow pulp supplemented with wheat bran in the ratio of 4:1 resulted in the highest filter paper cellulase (FPase) activity of 13.4 IU/gds whereas endo-1,4-β-glucanase (CMCase) activity was found to be best when kinnow pulp was supplemented with wheat bran in the ratio 3:2 using Mandel Weber (MW) medium. β-glucosidase activity of 18 IU/gds was again found to be maximum in treatment involving 3:2 ratio of kinnow pulp to wheat bran in MW medium. However, supplementing kinnow pulp with wheat bran in 3:2 using water as medium resulted in an FPase:β-glucosidase ratio of nearly 1:1 which is considered to be most appropriate for achieving ideal saccharification efficiency in case of pretreated lignocellulosic material. Thus, this study involved the utilisation of kinnow pulp for production of cellulases and demonstrated that a substrate which does not find any commercial significance and causes environmental pollution due to its poor disposal holds promise as a substrate for production of cellulases.

Optimization of Fermentation Parameters for Higher Lovastatin Production in Red Mold Rice through Co-culture of Monascus purpureus and Monascus ruber

Abstract: Monascus, fermented rice (red mold rice), has been found to reduce the serum total cholesterol and triglyceride due to presence of lovastatin. Lovastatin acts as an inhibitor of 3-hydroxy-3-methyl glutaryl coenzyme A reductase. Coculture of Monascus purpureus MTCC 369 and Monascus ruber MTCC 1880 was used to produce red mold rice by solid-state fermentation. Optimization of different fermentation process parameters such as temperature, fermentation time, inoculum volume, and pH of the solid medium was carried out by Box–Behnken’s factorial design of response surface methodology to maximize lovastatin concentration in red mold rice. Maximum lovastatin production of 2.83 mg/g was predicted at 14th day in solid medium under optimized process condition.

Selection of an Edible Starch Coating for Minimally Processed Strawberry

Abstract: Edible coatings can represent an alternative for extending post-harvest life of perishable fruits, as strawberries. In this work, the effect of cassava starch edible coatings, added or not of potassium sorbate, on mechanical properties, surface color, sensory acceptance, and respiration rate of strawberries was evaluated in order to choose the best coating conditions to minimally processed strawberries. Integrity and water-vapor resistance of the coatings were also evaluated. Three different concentrations of cassava starch (1%, 2%, and 3%) and two concentrations of potassium sorbate (0.05% and 0.10%) were used in the coatings formulations. Minimally processed strawberries without coating were used as control samples. The strawberries treated with different coatings and control fruits did not present differences regarding mechanical properties, surface color, and all the sensory attributes evaluated. A good integrity of cassava edible coatings on strawberries surface was observed for 2% and 3% starch concentration and the use of coatings, in these concentrations, reduced the strawberries respiration rate, representing a possibility to extend the shelf life of fruits. All coatings showed beneficial effects on increasing the water vapor resistance of the samples, but a significant increase was obtained only with the use of coating with 3% of starch. The potassium sorbate improved significantly the resistance to water vapor, but no differences were observed between the two concentrations studied. Based these results, the coatings with 3% of cassava starch and 3% of cassava starch +0.05% of potassium sorbate were those selected for future shelf life study of minimally processed strawberries.

Ultraviolet Treatment of Orange Juice to Inactivate E. coli O157:H7 as Affected by Native Microflora

Abstract: The effect of yeast concentration on ultraviolet (UV) inactivation of five strains of Escherichia coli O157:H7 from different sources, inoculated both individually and simultaneously in orange juice, was analyzed and mathematically modeled. The presence of yeast cells in orange juice decreases the performance of UV radiation on E. coli inactivation. UV absorption coefficients in the juice increased with increasing yeast concentration, and higher UV doses were necessary to inactivate bacterial strains. UV intensities of I = 3.00 ± 0.3 mW/cm2 and exposure times (t) between 0 and 10 min were applied; radiation doses (energy, E = I × t) ranging between 0 and 2 J/cm2 were measured using a UV digital radiometer. All the tested individual strains showed higher resistance to the treatment when UV radiation was applied at 4 °C in comparison to 20 °C. UV inactivation of E. coli O157:H7 individual strain was satisfactory fitted with a first order kinetic model. A linear relationship was found between UV absorptivities and D values (radiation doses required to decrease microbial population by 90%) for each strain. The dose required to reach 5-log reduction for the most unfavorable conditions that is the most UV resistant strain, and maximum background yeast concentration was 2.19 J/cm2 at 4 °C (corresponding to 11 min of UV treatment) and 2.09 J/cm2 at 20 °C (corresponding to 10.55 min of UV treatment). When a cocktail of strains was inoculated in orange juice, the logistic equation was the best model that fits the experimental results due to the deviation from the log-linear kinetics. The UV resistance between strain cocktail and single strain were mathematically compared. Slopes of the decline curves for strain cocktail at high UV doses were lower than the slopes of the log-linear equation calculated for the individual strains, even for the most resistant one. Therefore, microbial inactivation tests using a cocktail of strains are particularly important to determine the performance of the UV inactivation treatment.

Optimization of Additive Combination for Improved Soy–Wheat Bread Quality

Abstract: The protein content of ordinary white bread ranges from 8% to 9%. Specialty breads can be made with 13–16% protein by including soy protein. However, incorporating high levels of soy protein depresses loaf volume, gives poor crumb characteristics, and decreases acceptability. The objective of this study was to determine the influence of sodium stearoyl-2-lactylate (SSL), transglutaminase (TG), and xylanase (HE) on high-protein dough properties and bread quality and to improve dough handling and bread quality of soy–wheat bread by using an optimized additive combination. The influence of SSL, TG, and HE on soy–wheat dough and bread properties was modeled by response surface methodology. The negative effect of soy products on gluten network was confirmed. With regards to the additives tested and their combination, TG showed a major improving effect on dough rheological properties and crumb uniformity, whereas SSL and HE enhanced both dough and bread quality. The best formulation tested produced an increment of approximately 65% soy–wheat bread volume and a decrease of 79% and 71% crumb hardness and chewiness, respectively, compared with the standard formulation.

Rapid Detection of Microorganisms Using Image Processing Parameters and Neural Network

Abstract: A rapid and cost-effective technique for identification of microorganisms was explored using fluorescence microscopy and image analysis, and classification was done with trained neural network. The microorganisms used in this study are Bacillus thuringiensis (C399), Escherichia coli K12 (ATCC 10798), Lactobacillus brevis (LJH240), Listeria innocua (C366), and Staphylococcus epidermis (LJH343). After staining the microorganisms with fluorescent dyes [diamidino-2-phenyl-indole and acridine orange (AO)], images of the microorganisms were captured using a digital camera attached to a light microscope. Geometrical, optical, and textural features were extracted from the images using image analysis. Parameters extracted from images of microorganisms stained with AO gave better results for classification of the microorganisms. From these parameters, the best identification parameters that could classify the microorganisms with higher accuracy were selected using a probabilistic neural network (PNN). PNN was then used to classify the microorganisms with a 100% accuracy using nine identification parameters. These parameters are: 45° run length non-uniformity, width, shape factor, horizontal run length non-uniformity, mean gray level intensity, ten percentile values of the gray level histogram, 99 percentile values of the gray level histogram, sum entropy, and entropy. When the five microorganisms were mixed together then, also the PNN could classify the microorganisms with 100% accuracy using these nine parameters.

Blanching of Strawberries by Ohmic Heating: Effects on the Kinetics of Mass Transfer during Osmotic Dehydration

Abstract: The effect of blanching by ohmic heating (OH) on the kinetics of osmotic dehydration of strawberries was studied. Ohmic heating parameters obtained at two temperatures (65 and 85 °C). The osmotic dehydration (OD) parameters are the temperature (26 and 37 °C) and the sucrose in osmotic solution (30–70 °B). An approximate solution of Fick’s law for unsteady state mass transfer in spherical configuration has been used to calculate the effective diffusion coefficients of water and sucrose. Results show that ohmic heating increases drastically the mass transfer and the effective diffusion rates. After 4 h of OD (without OH) in a sucrose solution (at 37 °C and 70 °B), the dry matter of the untreated strawberry halves was 20.3%; while it reached 68% when OD was combined with blanching by OH at 85 °C for 3-min. Ohmic blanching permits the effective damage of cells by combination of electrical and thermal effects. That result has an important enhancement of water and sugar transfers during osmotic dehydration of strawberries.

Fractioned High Pressure Extraction of Anthocyanins from Elderberry ( Sambucus nigra L.) Pomace

Abstract: Fractionated high pressure extractions from dry and in natura elderberry pomace were performed in order to obtain anthocyanin rich extracts. Experiments were carried out using CO2 supercritical fluid extraction followed by enhanced solvent extraction (ESE) with CO2/EtOH–H2O mixtures (1–100%, v/v), to obtain anthocyanin rich fractions in the second step, at 313 K and ~20 MPa. Higher extract yields, anthocyanin contents and antioxidant activities occurred by the presence of water, both in the raw material and in the solvent mixture. The CO2 dissolved in the ESE solvent mixture favored either anthocyanin contents or antioxidant activities, which were not directly related. Comparing to the literature data for elderberries and grapes, these fractions had higher anthocyanins contents. From these results, an added economical value to this agroindustrial residue is proposed, using solvents and techniques “generally regarded as safe” in the food and pharmaceutical industries.

A Case Study on Optimization of Biomass Flow During Single-Screw Extrusion Cooking Using Genetic Algorithm (GA) and Response Surface Method (RSM)

Abstract: In the present study, response surface method (RSM) and genetic algorithm (GA) were used to study the effects of process variables like screw speed, rpm (x1), L/D ratio (x2), barrel temperature (°C; x3), and feed mix moisture content (%; x4), on flow rate of biomass during single-screw extrusion cooking. A second-order regression equation was developed for flow rate in terms of the process variables. The significance of the process variables based on Pareto chart indicated that screw speed and feed mix moisture content had the most influence followed by L/D ratio and barrel temperature on the flow rate. RSM analysis indicated that a screw speed > 80 rpm, L/D ratio > 12, barrel temperature > 80 °C, and feed mix moisture content > 20% resulted in maximum flow rate. Increase in screw speed and L/D ratio increased the drag flow and also the path of traverse of the feed mix inside the extruder resulting in more shear. The presence of lipids of about 35% in the biomass feed mix might have induced a lubrication effect and has significantly influenced the flow rate. The second-order regression equations were further used as the objective function for optimization using genetic algorithm. A population of 100 and iterations of 100 have successfully led to convergence the optimum. The maximum and minimum flow rates obtained using GA were 13.19 × 10−7 m3/s (x1 = 139.08 rpm, x2 = 15.90, x3 = 99.56 °C, and x4 = 59.72%) and 0.53 × 10−7 m3/s (x1 = 59.65 rpm, x2 = 11.93, x3 = 68.98 °C, and x4 = 20.04%).

Mild Thermal Process Combined with Vanillin Plus Citral to Help Shorten the Inactivation Time for Listeria innocua in Orange Juice

Abstract: The response of Listeria innocua (surrogate for Listeria monocytogenes) to combined treatments involving moderate temperatures (57 to 61 °C) and the addition of different levels of citral (0 to 75 ppm) was assessed to obtain a minimally processed orange juice. The presence of citral notoriously increased the bactericidal effect of mild heating treatment. This effect did not depend on the amount of added citral at all assayed temperatures. In a second stage, combinations of two natural antimicrobials (vanillin and citral) were assessed in order to find the most effective inactivation treatment in orange juice. Vanillin (900–1,100 ppm) and citral (25 ppm) combined with mild heating treatment (52 or 57 °C) were tested against L. innocua in orange juice. The addition of 900 ppm vanillin and 25 ppm citral halved or more the time required to achieve five logarithmic cycles of reduction at both temperatures with respect to thermal treatment without antimicrobial addition. The increase in the maximum growth rate calculated from the modified Gompertz model properly correlated with the increasing vanillin level for a given citral concentration. Complementary information was obtained from successfully fitting a Weibullian model to the nonlinear semilogarithmic survival curves: The addition of vanillin and citral significantly increased the bactericidal effect of mild thermal treatment, changing the distribution of inactivation times and obtaining narrower frequency shapes with lower variance and mode values. The combination of vanillin and citral with mild heating treatment resulted in an innovative alternative to minimize detrimental effects caused by thermal processing of fruit juices. In addition, a consumer panel evaluated them with an acceptable overall pleasantness.

Computer vision and stereoscopy for estimating firmness in the salmon (Salmon salar) fillets.

Abstract: The computer vision and a stereoscopy technique were used to characterize and detect changes in the capacity of the salmon fillet surface to recover its original form after a constant weight was applied. A curvature index (associated to fillet firmness) calculated by means of 3D information data obtained with the stereoscopy technique from the fat stripe on the fillets was estimated over 6 months and was suggested as a characteristic of the recovery property of the fresh salmon fillet surface. Simultaneously, instrumental firmness using a LFRA1500 texture was measured. The values for the fresh salmon fillet measurement curvature index during a period of 6 months were established in the range of 0.05 and 0.10 (dimensionless), and this value was used in the experiments to represent fresh salmon fillets. Changes in the curvature index (associated with similar changes in firmness) for salmon fillet surface treated with enzymes (pepsin and papain) were registered on the second day during storage at 2 °C. In general, stereoscopy is a technique that can be used on salmon fillets to detect changes in the recovery properties of the salmon fillet surface and to determine when salmon fillets can be classified as a fillet that has not been processed with enzymes.

Extracts of Mexican Oregano ( Lippia berlandieri Schauer) with Antioxidant and Antimicrobial Activity

Abstract: Antimicrobial activity of fractions obtained from Mexican oregano (Lippia berlandieri Schauer) chloroform extract was tested by growth inhibition against Escherichia coli, Staphylococcus aureus and Bacillus cereus, and antioxidant capacity was tested by inhibition of linoleic acid oxidation. Fractions were obtained by differences in polarity or structure (phenolic and non-phenolic fraction). Gram-positive organisms were more susceptible to Mexican oregano extracts. Fraction 3 (by polarity) and phenolic fractions I, II, III, IV and V were the extracts with higher antimicrobial activity. The non-phenolic fraction had effect against B. cereus. Polarity fraction 5 and phenolic Fraction II had a high antioxidant capacity; a 0.08% concentration of fraction 5 had a similar effect as butylated hydroxytoluene at 0.01% concentration. Fractions of Mexican oregano with different polarity and functional groups had antioxidant and antimicrobial activity and can be used in a variety of applications.

Kinetics of Polyphenol Losses During Soaking and Drying of Cider Apples

Abstract: A regular consumption of fresh or processed fruits can contribute to preventing cardiovascular diseases and cancer. Polyphenols, which are naturally present in fresh apples (Malus x domestica), are widely acknowledged as antioxidants. Cider apples contain high concentrations of polyphenols, but their composition differs markedly as a function of cultivar. Two of which were studied in this respect. The first cultivar was Marie Menard, which is highly concentrated in polyphenols and has a standard profile showing high levels of hydroxycinnamic acids and monomeric catechins, widely involved in oxidation reactions catalyzed by the polyphenol oxidase; the second one was Guillevic, which has an atypical phenolic profile for a cider apple, with highly polymerized procyanidins and no monomeric catechins, which thus induces a low sensitivity to enzymatic browning. Both cultivars were subjected to osmotic dehydration at two temperatures (45 and 60 °C) or to convective air-drying, and a combination of the two processes was also tested. Phenolic compounds were quantified by high performance liquid chromatography for various processing times and regardless of the quantity of impregnated sugar. The results revealed different behaviors depending on the polyphenolic groups of compounds. Procyanidins were better preserved by the processes than hydroxycinnamic acids or monomeric catechins. Indeed, these latter groups of polyphenols were first of all involved in enzymatic browning but could also diffuse more easily as their molecular weight was lower. Polyphenol retention was also dependent on the process applied. Polyphenols were better retained by convective drying than by osmotic dehydration, and when soaking was applied as a pretreatment, polyphenol losses were limited during subsequent drying. Moreover, the level of sucrose impregnation could mask the astringency of procyanidins.

Effects of Processing Conditions on Single Screw Extrusion of Feed Ingredients Containing DDGS

Abstract: Distillers dried grains with solubles (DDGS), a feed coproduct from the fuel ethanol industry, has been shown to be a viable potential alternative protein source for aquaculture feeds. To investigate this, three isocaloric (3.5kcal/g) ingredient blends containing 20, 30, and 40% DDGS, with a net protein adjusted to 28% (wet basis, wb), were prepared for use as Nile tilapia feed. Extrusion processing was then conducted using three DDGS contents (20, 30, and 40%, wb), three moisture contents (15, 20, and 25%, wb), three barrel temperature gradients (90–100–100°C, 90–130–130°C, and 90–160–160°C), and five screw speeds (80, 100, 120, 140, and 160rpm) using a single screw laboratory extruder. Several processing parameters, including mass flow rate, net torque required, specific mechanical energy consumption, apparent viscosity, and temperature and pressure of the dough inside the barrel and die, were measured to quantify the extrusion behavior of the DDGS-based blends. For all blends, as the temperature profile increased, mass flow rate exhibited a slight decrease, die pressure decreased, and apparent viscosity exhibited a slight decrease as well. Likewise, the net torque requirement, specific mechanical energy consumption, and apparent viscosity decreased as screw speed increased, but mass flow rate increased. Additionally, as moisture content increased, die pressure decreased. At higher temperatures in the barrel and die, the viscosity of the dough was lower, leading to lower torque and specific mechanical energy requirements. Increasing the DDGS content, on the other hand, resulted in a higher mass flow rate and decreased pressure inside the die. As demonstrated in this study, the selection of suitable temperature and moisture content levels are critical for processing DDGS-based ingredient blends.

Effect of Processing Methods on Physical, Chemical, Rheological, and Sensory Properties of Okra (Abelmoschus esculentus)

Abstract: Effects of freezing/thawing, sun drying, solar drying, and foam-mat drying on physical, chemical, rheological, and sensory attributes of okra were investigated. Average poured bulk and tapped bulk densities of sun-dried, solar-dried, and foam-mat-dried okra were 800 and 950, 715 and 765, 355 and 367 kg/m3, respectively. Minimum and maximum porosity of sun-dried, solar-dried, and foam-mat dried okra were 55.70% and 62.60%, 50.06% and 53.30%, 60.90% and 62.87%, respectively. Sun-dried and solar-dried okra showed higher L*, a*, and chroma values than frozen/thawed and foam-mat-dried okra. Within a temperature range of 80–40 °C, viscosity of fresh, frozen/thawed, foam-mat-dried, solar-dried, and sun-dried okra were 0.055–0.080, 0.055–0.075, 0.050–0.073, 0.005–0.065, and 0.005–0.022 Nsm−2, respectively. Sensory evaluation showed no significant difference (p < 0.05) between fresh, frozen/thawed, and foam-mat dried okra in color, aroma, and overall acceptability. Sun-dried and solar-dried okra were significantly poorer (p < 0.05) in color, aroma, taste, and overall acceptability.