Microwave–Vacuum Drying of Strawberries with Automatic Temperature Control

Food and Bioprocess Technology - A microwave–vacuum drying system with the ability of automatic temperature control was developed for strawberry drying in order to obtain a high-quality...     

Pretreatments Effect in Drying Behaviour and Colour of Mature and Immature ‘Napolitana’ Sweet Cherries

The effect of different treatments on drying behaviour and colour of mature and immature cherries (Napolitana var.) has been studied. Drying was carried out at 70 °C with air at 4 m/s speed and 8 % relative humidity, and fruits were subjected to the following pretreatments: B (blanching), F (freezing), P (pitting), B?+?Dip1 (blanching and immersion in acid solution) and B?+?Dip1?+?Dip2 (blanching and immersion in saline acid solution) which affected the drying behaviour and the colour retention of fruits for both maturity degrees. Regarding skin colour in terms of chroma and hunter a parameters, the anthocyanin retention and the evaluation of anthocyanin degradation index, both B?+?dip1 and B?+?dip1?+?dip2 pretreatments led to better-quality dry products, mainly in mature cherries. Moreover, the incorporation of blanching in the combined pretreatments significantly reduced drying time. Lewis, Page and Logarithmic models were selected to represent in a simple way the thin-layer drying characteristics of pretreated cherries and to predict the process times required to reduce the moisture content to about 0.3–0.4 kg water/kg dm (a _w?≤?0.6). Logarithmic model provided the best fit to experimental data for each drying curve, based on the statistical tests used for evaluation.     

Effect of Selected Pretreatments on Convective Drying Process of Blueberries (var. O’neil)

The effects of different pretreatments on the convective drying kinetics of blueberries (var. O??Neil) at 70?°C were investigated. The sodium hydroxide, enzymatic, microwaves, and high hydrostatic pressure pretreatments were applied and compared with control samples (non-pretreated). In order to simulate experimental drying data, the following mathematical models were selected: logarithmic, two terms, modified Henderson?CPabis, Midilli?CKucuk, and Weibull. Fick??s second law of diffusion was applied to determine the water diffusion coefficient for all the treatments. All pretreatments decreased significantly the drying time of the control samples. High hydrostatic pressures together with microwave pretreatments presented lower drying times than non-pretreated samples. Moreover, based on statistical test results, Weibull and modified Henderson?CPabis models presented the best fit for the experimental drying curves. Thus, both models can be satisfactorily applied to estimate the drying time of blueberries as well as to evaluate the effects of different pretreatments on fruit drying rates.     

Effect of HPMC–Anthocyanin Packaging Color and Oxygen Permeability on Salmon Oil Preservation

Antioxidant food packaging films were successfully developed by incorporation of anthocyanin compound (liquid extract from natural sources) into hydroxypropyl methylcellulose matrix. Film color and oxygen barrier properties were measured. Red color of films containing anthocyanin compound (AC) showed good control of light transmission in comparison with control (transparent) films. Barrier properties of these films showed that addition of AC decreased oxygen permeability, possibly due to hydrogen bonding between polymer OH groups and those of anthocyanin compound. The effectiveness of bioactive films was investigated by packaging salmon oil. Changes in oil color, headspace oxygen consumption, conjugated dienes, polyene index, and C–H stretching vibration of cis-double bond (=CH) showed that, in general, AC films improved salmon oil stability. Films with 2, 3, and 4 % (v/v) AC offered the best protection against lipid oxidation due to improved barrier properties against light and oxygen.     

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

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).     

Determination of Total Antioxidant Capacity of Lipophilic and Hydrophilic Antioxidants In the Same Solution by Using Ferric–Ferricyanide Assay

The purpose of this work is to develop a simple, low-cost, and diversely applicable antioxidant capacity assay, the ferric–ferricyanide method based on Prussian blue formation, for both lipophilic and hydrophilic antioxidants in food matrices. The trolox equivalent antioxidant capacities of various antioxidant compounds were calculated with respect to the ferric–ferricyanide, FRAP, and modified CUPRAC methods. The linear calibration curves of the ferric–ferricyanide assay for lipophilic antioxidants (as absorbance vs. concentration) in 1:9 (v/v) H₂O–acetone mixture solution with and without 2% MβCD were comparatively drawn. Simultaneous determination of lipophilic and hydrophilic antioxidants could be achieved without using MβCD. Testing of synthetic mixtures of lipophilic and hydrophilic antioxidants in 1:9 (v/v) H₂O–acetone medium with the proposed method yielded the theoretically expected antioxidant capacities, considering the additivity of absorbances of constituents obeying Beer’s law. The proposed assay is simple, versatile, and cost-effective; its reagents are cheap and stable, and can be performed using a simple colorimeter.     

Puffing Characteristics of Parboiled Milled Rice in a Domestic Convective–Microwave Oven and Process Optimization

Microwavable products are gaining worldwide acceptance as convenience foods, where hygiene can be maintained when processed in small quantities at the domestic level. One such ready to eat products are puffed or popped starchy grains like corn, rice, sorghum, etc. Owing to its high starch content, rice has high expandability, and the puffed rice produce thence has better digestibility. Considering these aspects, an attempt was made to produce puffed rice in a domestic convective–microwave oven. Puffing characteristics were studied for Gurjari variety of rice at 14 % (wb) moisture content for different preheating temperatures of the glass base plate (180, 200, and 220 °C), microwave power level (300, 600, and 900 W), and residence time (10–100 s), from which the range of residence time was selected for the optimization study. It was found that the puffing of rice was better at higher power level and preheating temperature of the base plate, and puffing started only after certain residence time. Further study was carried out to optimize the process parameters by using response surface methodology, for a Box–Behnken design at three levels for four parameters, i.e., moisture content (12, 14, and 16 % wb), preheating temperature of the base plate (180, 200, and 220 °C), microwave power level (300, 600, and 900 W), and residence time (50, 60, and 70 s). The optimized conditions were found to be 14 % (wb), 220 °C, 900 W, and 60 s. The second-order polynomial model was validated by conducting three trials at the optimized point and found to be agreeing with the predicted values.     

Effect of Microwave Radiation Pretreatment of Rice Flour on Gluten-Free Breadmaking and Molecular Size of β-Glucans in the Fortified Breads

Cereal β-glucan concentrates can be used in gluten-free breads to improve dough handling properties and quality of final products as well as to enhance their nutritional value; however, the presence of endogenous β-glucanases in rice flour, in combination with prolonged mixing, fermentation, and proofing time, can cause a substantial reduction in β-glucan molecular weight, affecting detrimentally their efficacy for bioactivity. In this study, microwave (MIWA) heating was applied to the rice flours before breadmaking at different flour water contents (13–25%) and treatment times (0-4 min) to reduce β-glucanase activity. Gluten-free breads made from the MIWA-treated rice flours were fortified with oat β-glucan concentrate to enhance their nutritional profile. The molecular weight of added β-glucan in the final products increased with increasing both flour water content and time of MIWA treatment, reflecting the magnitude of residual β-glucanase activity in the flour. Pretreatment with MIWA radiation for 4 min of the rice flour tempered at 25% moisture resulted in negligible residual β-glucanase activity and preserved to a great extent the molecular weight of β-glucans in the enriched breads. End-product quality was not affected by flour MIWA pretreatment, and even a slightly higher loaf specific volume was noted for breads made from the MIWA-treated flours (4 min MIWA at 25% moisture content) compared to that of untreated flour. These findings can contribute to the improvement of nutritional value of rice-based gluten-free breads for celiac consumers as well as of any β-glucan-containing yeast-leavened bakery product without altering its sensorial attributes. Additional studies are still required for further evaluation of the effect of more intense microwave treatment on rice flour and its application on breadmaking.     

Effect of Piperine,a Major Component of Black Pepper,on the Intestinal Absorption of Fexofenadine and Its Implication on Food–Drug Interaction

ABSTRACT: The present study aimed to investigate the effect of piperine, a major component of black pepper, on the oral exposure of fexofenadine in rats. Pharmacokinetic parameters of fexofenadine were determined in rats following an oral (10 mg/kg) or intravenous (5 mg/kg) administration of fexofenadine in the presence and absence of piperine (10 or 20 mg/kg, given orally). Compared to the control group given fexofenadine alone, the combined use of piperine increased the oral exposure (AUC) of fexofenadine by 180% to 190% while there was no significant change in C_max and T_1/2 of fexofenadine in rats. The bioavailability of fexofenadine was increased by approximately 2-folds via the concomitant use of piperine. Furthermore, T_max tends to be increased which might be attributed to the delayed gastric emptying in the presence of piperine. In contrast, piperine did not alter the intravenous pharmacokinetics of fexofenadine, implying that piperine may increase mainly the gastrointestinal absorption of fexofenadine rather than reducing hepatic extraction. In conclusion, piperine significantly enhanced the oral exposure of fexofenadine in rats likely by the inhibition of P-glycoprotein-mediated cellular efflux during the intestinal absorption, suggesting that the combined use of piperine or piperine-containing diet with fexofenadine may require close monitoring for potential drug–diet interactions.     

The Effect of Irradiation and Heat Treatment on Composition and Antioxidant Properties of Culinary Herbs and Spices — A Review

Besides the positive effects, γ-irradiation and heat treatment of foods usually lead to changes in their structure or composition, thus influencing their quality. In view of the fact that herbs and spices are important source of antioxidants in a human diet, any kind of treatment can have an impact on their antioxidant status, as well. In this contribution, we review the effects of γ-radiation and heat treatment on some constituents and antioxidant properties of culinary herbs and spices. Both methods of treatment result in some common qualitative changes in herbs and spices, mostly in the content of polyphenols or volatile components. The results of antioxidant testing assays are sometimes contradictory in observed effect or trends, in dependence on the manner of treatment and character of spice matrix. Based on this review, the effects of γ-radiation or heat processing on antioxidants, or the vitamin content in herbs and spices is still lacking, which makes the direct assessment of the effect of treatment on the antioxidant status of herbs and spices practically impossible. However, the changes in composition that have been observed to date suggest that they have only a small effect on the behavior of herbs and spices in a real food matrix.     

Effect of frozen storage and freeze–thaw cycles on the rheological and baking properties of frozen doughs

The effects of prolonged frozen storage and repeated partial freeze–thaw cycles on the rheological and baking properties of nine commercial wheat cultivars were evaluated. The gluten strength of the cultivars ranged from medium to high, whereas the starch swelling characteristics were similar for most cultivars, except Parshall, which exhibited exceptionally high swelling properties. The doughs were subjected to frozen storage for 4–12 weeks, with and without freeze–thaw cycles. The enthalpy of freezable water was significantly affected by initial freezing, whereas, the rheological properties of the doughs were more susceptible to freeze–thaw cycles. After baking, all cultivars produced bread of acceptable quality, although cv. Parshall exhibited the highest crumb softness, irrespective of the frozen treatment. Results indicate that flours with high starch swelling characteristics, along with moderately high gluten strength, may be most ideal for producing optimum quality frozen doughs, with good shelf life and baking properties.     

Effect of the incorporation of antioxidants on physicochemical and antioxidant properties of wheat starch–chitosan films

Blend edible films were prepared from wheat starch (WS) and chitosan (CH) with glycerol as plasticizer. Four active ingredients (antioxidants) were added, namely basil essential oil, thyme essential oil, citric acid and α-tocopherol. The starch:antioxidant mass ratio was 1:0.1. Prior to characterisation, the films were conditioned at 25 °C–53%RH as to their structural, mechanical, optical and barrier properties. The antioxidant capacity of the active ingredients was determined by means of a spectrophotometric method. The incorporation of antioxidants led to a heterogeneous film microstructure, mainly in those containing α-tocopherol, which affected the surface roughness. Yellowness was induced in films when α-tocopherol was added and no notable colour changes were observed in the other cases, although all the antioxidants increased the transparency of the films. Despite of the fact that the mechanical properties were barely affected by the incorporation of antioxidants, citric acid promoted an increase in the elastic modulus but a decrease in film stretchability. The water vapour barrier properties of the films were only slightly improved when citric acid and α-tocopherol were added, whereas the oxygen barrier properties were significantly improved in all cases. The greatest antioxidant capacity of the films was reported for films containing α-tocopherol, which exhibited the highest antioxidant power.     

Effect of the structure of monoglyceride–oil–water gels on aroma partition

The aim of the present research was to study the aroma partition properties of saturated monoglyceride–oil–water gels. To this purpose, gels added with lemon oil were prepared mixing water, sunflower oil and commercial saturated monoglycerides. Three mixtures containing different ratios between the ingredients were considered. The gel characteristics were studied by synchrotron X-ray diffraction (XRD), calorimetry, polarized light microscopy and rheological measurements. The aroma partition was studied by using HSGC analysis.The gel structure is made of a multilamellar crystalline network, in which monoglycerides form shells encapsulating oil. Depending on the ratio between ingredients, the gel shows different rheological behaviour. The structured multilamellar phases greatly affect the partition of aroma evidencing the capability to entrap lipophilic compounds within the monoglyceride/oil shells. Since the aroma entrapping capacity showed by monoglyceride structures could greatly affect the perceived aroma intensity of the final product, this effect should be carefully taken into account during the development of new formulations.     

Effect of processing history on the functional and structural characteristics of starch–fatty acid extrudates

Normal maize starch was extruded with and without the addition of fatty acid potassium salts in a twin screw cooker extruder equipped with a slit die rheometer, at 100, 120, 140 or 160 °C barrel temperatures and at screw speeds 20, 91, 161 or 227 rpm. The in line melt viscosity measurements showed that the flow behaviour of the starch system was influenced by the addition of either myristic or palmitic acids used. The examination of functional properties of the extrudates such as bulk density, water solubility index, expansion ratio, degree of gelatinization and water adsorptivity indicated that the addition of fatty acids affected the functionality of starch systems. That is, the extrudate texture became more cohesive and compact whereas the water solubility exhibited by the system was decreased. Structural studies indicated that the crystallinity of starch–fatty acid extrudates was higher than that of the starch systems without fatty acid whereas all extrudates exhibited high glass transition temperatures and their structure was very rigid and brittle.     

High Intensity Ultrasound as an Abiotic Elicitor—Effects on Antioxidant Capacity and Overall Quality of Romaine Lettuce

The effect of ultrasound treatment at low acoustic power density (APD) on antioxidant capacity and overall quality of Romaine lettuce was evaluated. Whole leaf lettuce was treated with ultrasound (25 kHz) at APD of 26 W/L for 1–3 min and stored at room temperature for up to 150 h. Quality indices examined included color, texture, total phenolics, antioxidant capacity, and sensory properties. Phenylalanine ammonia-lyase (PAL) activity of lettuce from different treatments was monitored during storage. There were no differences in sample quality attributes between ultrasound treatment and control immediately after treatment. Lettuce treated with ultrasound exhibited an increase in PAL activity after storage for 60 h, resulting in production of phenolic compounds as secondary metabolites and enhancement of antioxidant capacity. Ultrasound-treated samples did not exhibit deterioration during storage, and under certain conditions, it delayed enzymatic browning and maintained better overall quality. A hypothetical model for the effect of low APD ultrasound as an abiotic elicitor on fresh produce was proposed based on the finding of present study and evidence from previous reports on response of cell cultures to ultrasond treatment.     

Effect of pectin, starch, and locust bean gum on the interfacial activity of monostearin and β-lactoglobulin

The behavior of some hydrocolloids widely used as stabilizers of low-oil-content water emulsions (starch, pectins, and a locust bean gum-pectin blend) at the air-water and model oil-water interface is analyzed. Their influence on the surface and interface activity of typical food emulsifiers, such as β-lactoglobulin and monostearin, is also considered. It is demonstrated that the greatest interfacial activity is provided by one of the commercial pectins studied. It is capable of modifying the characteristics of monostearin and β-lactoglobulin interfacial films in a different way depending on both the nature of the oil phase and the type of surfactant used. PRACTICAL APPLICATION: This research may contribute not only to enhance the final-consumer life quality by optimizing low-oil-content food emulsion formulations which contain \"natural\" stabilizers, but also to increase the added value of by-products of some fruit juices as well as of sugar factories since pectin can be manufactured not only from citrus and apple peels but also from sugar beet pulps.