Changes on Enological Parameters of White Wine Packaged in Bag-in-Box during Secondary Shelf Life

ABSTRACT:  This study investigated the effects of temperature (22, 35, and 45 °C), storage time (48, 30, and 15 d), and packaging type on the quality of white wine in bag-in-box (BIB) during the secondary shelf life. Several enological parameters (color and contents of free and total SO₂, total aldehyde, and total phenol) were monitored and correlated with oxygen transmission rate (OTR) and Fourier transform infrared (FTIR) spectral data. Time and temperature had significant effects on color development and SO₂ depletion during storage. The increased absorbance at 420 nm was correlated with decreases of free SO₂ and total SO₂. Overall, total phenol content correlated negatively with total aldehyde content. The variance of the enological parameters can be correlated with the OTR data, indicating the barrier properties for the tested packages were different. FTIR–ATR spectra of the wine were analyzed chemometrically using PLS algorithm. The resulting models were able to predict the  A ₄₂₀, free SO₂, total SO₂, total phenol, total aldehyde, and storage time of the wines. This technique can potentially be used as an efficient tool to evaluate the quality of wine.     

The Flavonoid Eriodictyol as Substrate of Peach Polyphenol Oxidase

ABSTRACT: Spectral changes produced in the oxidation of eriodictyol by peach polyphenol oxidase were followed over time. A product with λ_max= 390 nm was seen to appear before another with λ_max= 475. The product absorbing at 390 nm must correspond to the o -quinone derived from eriodictyol. The compound absorbing at 475 nm must be derived from this eriodictyol-o-quinone. Progress curves at this wavelength revealed a lag, the length of which varied with enzyme and substrate concentrations. This lag must have been caused by chemical reactions taking place after the enzymatic reaction. When eriodictyol oxidation was studied in the presence of 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH), a potent nucleophilic reagent that reacts with the eriodictyol-o-quinone to form a dark pink product absorbing at 508 nm, the lag disappeared. When the kinetic parameter was evaluated in the presence of MBTH (K_m= 0.6 m M ), the results was similar to those obtained without MBTH. Eriodictyol oxidation was inhibited by tropolone, which behaved as a classic competitive inhibitor (K_I= 15 μ M ). The inhibition results reported show that eriodictyol oxidation was strictly dependent on the presence of polyphenol oxidase. In addition, other oxidase activities, such as laccase and H₂O₂ independent phenol oxidase, were not detected in the enzyme extract.     

p-HYDROXYPHENYLPROPIONIC ACID (PHPPA) AND 3,4-DIHYDROXYPHENYLPROPIONIC ACID (3,4-DPPA) AS SUBSTRATES FOR MUSHROOM TYROSINASE

p-Hydroxyphenylpropionic acid (PHPPA) and 3,4- dihydroxyphenylpropionic acid (3,4-DPPA) serve as substrates for tyrosinase. The Km value of 3,4-DPPA for tyrosinase is 1.3 mM. The yellow o-quinone of 3,4-DPPA (4-carboxyethyl-o-benzoquinone) (λ_max= 400nm), is detected initially and it is then converted to a red product(s) (λ_max= 480±10 nm), the o-quinone of 6,7-dihydroxy 3-dihydrocumarin (dihydroesculetin). When the concentration of the latter is relatively high, it polymerizes to a final brown product(s), characterized by an ill-defined spectrum.
H₂O₂ shortens the lag period of PHPPA hydroxylation, hastens the conversion of the yellow o-quinone of 3,4-DPPA to the red o-quinone of dihydroesculetin, and prevents the polymerization of the latter to the final brown product(s).
The relatively unstable o-quinone of 3,4-DPPA interacts with amines such as hydroxylamine (NH₂OH), p-aminosalicylic acid (PASA) and p-aminobenzoic acid (PABA), forming relatively stable final product(s) characterized by different spectra from those formed in their absence.
Acetohydroxamic acid (AHA) and salicylhydroxamic acid (SHAM) each has an effect on the spectrum of product(s) obtained when 3,4-DPPA is oxidized by tyrosinase, indicating that these hydroxamic acids derivatives interact with the o-quinone of 3,4-DPPA. The spectrum of the final product(s) was also different when 3,4-DPPA was oxidized by tyrosinase in the presence of benzenesulfinic acid than in its absence, suggesting the formation of a stable phenylsulfonyl derivative.     

Thermal Conductivity of Pear, Sweet-cherry, Apricot, and Cherry-plum Juices as a Function of Temperature and Concentration

ABSTRACT:  The thermal conductivity of 4 fruit (pear, sweet-cherry, apricot, and cherry-plum) juices was measured with a coaxial-cylinder (steady-state) technique. Measurements were made, temperature range 20 to 120 °C, at concentrations between 12.2 and 50 °Brix. The uncertainty of the thermal conductivity measurements was estimated to be less than 2%. A semitheoretical method for the prediction of thermal conductivity of juices was proposed. It was found that the prediction Model IV,  λ ( T , x )/λ ( T ₀, x ) = ( T / T ₀) ⁿ   , where  λ  is the thermal conductivity, x is the concentration, and T is the temperature, developed in this work can be adopted with satisfaction. The thermal conductivity of juices can be predicted just by knowing the thermal conductivity  λ₀  at a reference temperature   T ₀  .     

Viscous Food Matrix Influences Absorption and Excretion but Not Metabolism of Blackcurrant Anthocyanins in Rats

ABSTRACT:  The aim of the present study was to investigate the effect of a simultaneous intake of food and anthocyanins (ACNs) on ACN absorption, metabolism, and excretion. Blackcurrant ACNs (BcACNs) were dissolved in water with or without the addition of oatmeal and orally administered to rats, providing approximately 250 mg total ACNs per kilogram BW. Blood, urine, digesta, and tissue samples of the stomach, jejunum, and colon were subsequently collected at 0.25, 0.5, 1, 2, 3, 7, and 24 h. Identification and quantification of ACNs were carried out by Reversed phase-high-performance liquid chromatography (RP-HPLC) and liquid chromatography-mass spectrometry (LC-MS). Four major ACNs were present in the blackcurrant extract: delphinidin 3- O -glucoside, delphinidin 3- O -rutinoside, cyanidin 3- O -glucoside, and cyanidin 3- O -rutinoside. In plasma, the 4 ACNs of blackcurrant were identified and quantified. The time to reach maximal total ACN plasma concentration ( C _max BcACN/water = 0.37 ± 0.07 μmol/L; C _max BcACN/oatmeal = 0.20 ± 0.05 μmol/L) occurred faster after BcACN/water ( t _max= 0.25 h), than after BcACN/oatmeal administration ( t _max= 1.0 h). In digesta and tissue samples, the 4 original blackcurrant ACNs were detected. The relative concentration of rutinosides in the digesta increased during their passage through the gastrointestinal tract, while the glucosides decreased. Maximum ACN excretion in urine occurred later after BcACN/oatmeal than after BcACN/water administration (3 compared with 2 h). The 4 original ACNs of blackcurrant in their unchanged form, as well as several metabolites, were identified in the urine samples of both groups. The simultaneous intake of food affects ACN absorption and excretion in the urine, but not metabolism.     

CHARACTERIZATION OF POLYPHENOLOXIDASE FROM WILD PEAR (PYRUS ELAEGRIFOLIA)

Wild pear polyphenoloxidase (PePPO) was extracted and purified using a Sepharose 4B- l -tyrosine- p -amino benzoic acid affinity column. Optimum conditions for pH, temperature and heat inactivation were determined. At the optimum pH and temperature, K _M and V _max values for PePPO with catechol and pyrogallol were determined. The V _max/ K _M showed that PePPO has the greatest activity toward catechol. Optimum pH for PePPO was pH 6.0 using catechol as substrate. Optimum temperatures of PePPO for pyragallol and catechol were 65 and 35C, respectively. Enzyme activity decreased because of heat denaturation with increasing temperature. Inhibition of PePPO was investigated using p -aminobenzoic acid, ethyleneglycol, l -cysteine, l -tyrosine, sodium azide, p -aminobenzenesulfonamide, β-mercaptoethanol and dithiothreitol and catechol as substrate. Competitive-type inhibition was obtained with ethyleneglycol, l -cysteine, l -tyrosine, p -aminobenzenesulfonamide and dithiothreitol. Uncompetitive inhibition was obtained with β-mercaptoethanol, sodium azide and p -aminobenzoic acid. These results show that the most effective inhibitor for PePPO was dithiothreitol and that the type of inhibition depended on the origin of PPO.

PRACTICAL APPLICATIONS

In this present work, the properties of polyphenoloxidase in Pyrus elaegrifolia , including optimum temperature, optimum pH, substrate specificity and response to inhibitors, were studied.     

A NUMERICAL APPROACH TO COMPUTE TEXTURAL ATTRIBUTES OF COOKED RICE BY EXTRUSION TESTING

The cooked rice extrusion testing system consisted of a piston disc and a sample container with a pot base insert of one outlet. S _init (N/m) and S _max (N/m) are the slopes of the force–deformation curve in the packing and compression stages, respectively, and in the original method they are graphically drawn. Here, however, they were numerically computed as the differential of force to distance. The S _init and S _max from the numerical and drawing methods were compared in terms of data reproducibility and accuracy as described by coefficient of variation (CV) and correlation coefficient (CC), respectively. The numerically computed S _init and S _max showed lower CV: the new method, 0.03–0.06 and 0.03–0.06; the original method, 0.18–0.39 and 0.03–0.14, respectively. S _init by the new method showed higher CC with the adhesiveness of the samples: the new method, − 0.99; the original method, − 0.4. Therefore, the new method proved to be better in data accuracy and reproducibility.

PRACTICAL APPLICATIONS

The extrusion test is a practical instrumental method for measuring the textural properties of cooked rice. Nevertheless, its force–deformation curves are difficult to analyze quantitatively. This study attempted to improve the existing method for curve data analysis by applying a numerical method to compute the instrumental parameters. Based on the findings, this new method provided better data reproducibility and accuracy, and in terms of the instrumental parameters, can facilitate the implementation of cooked rice quality control in the field.     

COLORIMETRIC CHARACTERIZATION OF EGG YOLK AND EGG YOLK PRODUCTS

Procedures are suggested for COLOR-EYE® evaluation of various yolk forms and products. Chromaticity coordinates derived from COLOR-EYE determinations and the calculated dominant wavelength (λ_d), excitation purity (P_e) and luminous reflectance (Y_CIE) values were also determined for each yolk form and product analyzed. Characteristics of aged yolks included reduced λ_d and P_e and an increase in Y_CIE values; the greatest effects were at the highest levels of pigmentation concentration. Luminous reflectance values were substantially lowered by the addition of sugar and subsequent frozen storage; all other calorimetric criteria were relatively unchanged. Yolk age effects were negligible for the calorimetric characterization of yolks incorporated into product forms. Mayonnaise products provided the most consistent COLOR-EYE readings. These data suggest the feasibility of utilizing the COLOR-EYE, or similar instrumentation, as an objective method for the color characterization of various yolk products. Numerous options are available for converting data into other desired instrumentation values and terminology.     

Effect of winemaking practices on color indexes and selected bioactive phenolics of Aglianico wine

ABSTRACT:  Phenolic compounds are responsible for the sensory properties of wine as well as the properties beneficial to human health. The objective of this study was to establish the effect of the use of SO₂ and pectolitic enzymes in the prefermentative phase, maceration time, and oak aging on color, anthocyanins, tannins, (+)-catechin, (–)-epicatechin, rutin, trans -resveratrol, and quercetin content of Aglianico wine. Color indexes and phenolics were analyzed by HPLC and spectrophotometric methods. The addition of SO₂ and pectolitic enzymes before fermentation caused an increase in color intensity, color stability, total phenolics, anthocyanins, (+)-catechin, (–)-epicatechin rutin, trans -resveratrol, and quercetin content in Aglianico wine. Longer maceration times gave wines richer in total phenolics and with better chromatic characteristics. Storage in oak caused a decrease in anthocyanins, (+)-catechin, (–)-epicatechin, trans -resveratrol, and quercetin content but an increase in total phenolic content, and a stabilizing effect on color also occurred.     

Application of a Novel Small-Scale Sample Cleanup Procedure Prior to MALDI-TOF-MS for Rapid Pigment Fingerprinting of Red Wines

This study evaluates the anthocyanin and derived pigment composition of Vitis vinifera red wines of Vranec, Merlot, and Cabernet Sauvignon produced in 2006, 2007, and 2008 vintages from the Tikve? wine region in the Republic of Macedonia. Their profile was established using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) technique. A total of 22 anthocyanins and derived pigments have been identified in the samples including 10 anthocyanins, 1 ethyl-bridged flavanol–anthocyanin adduct, and 11 pyranoanthocyanins. MALDI-TOF-MS analysis was performed after solid-phase extraction of the wines by using, for the first time, the Zip-Tip® C18 stationary phase, introducing a novel small-scale sample cleanup procedure prior to the rapid MALDI-TOF-MS fingerprinting of wine samples. 2′,4′,6′-Trihydroxyacetophenone (dissolved in acetonitrile/water 1:1, v/v) was used as a matrix. The qualitative screening of anthocyanins and derived pigments with MALDI-TOF-MS confirmed the presence of glucoside, acetylglucoside, and p-coumaroylglucoside derivatives of anthocyanins in the wine samples. Furthermore, pyranoanthocyanins formed by reactions of anthocyanins with pyruvic acid and acetaldehyde, as well as flavanol–pyranoanthocyanins and ethyl-bridged flavan-3-ol-anthocyanin adduct pigments have been detected in the samples.     

Characterization of honey amylase

ABSTRACT:  The major α-amylase in honey was characterized. The optimum pH range and temperature were determined for the enzyme as 4.6 to 5.3 and 55 °C, respectively. The enzyme was stable at pH values from 7 to 8. The half-lives of the purified enzyme at different temperatures were determined. The activation energy for heat inactivation of honey amylase was 114.6 kJ/mol. The enzyme exhibited Michaelis–Menten kinetics with soluble starch and gave K _M and V _max values of 0.72 mg/mL and 0.018 units/mL, respectively. The enzyme was inhibited by CuCl (34.3%), MgCl₂ (22.4%), and HgCl₂ (13.4%), while CaCl₂, MnCl₂, and ZnSO₄ did not have any effect. Starch had a protective effect on thermal stability of honey amylase. Therefore, it might be critical to process or control the amylase in honey before incorporation into starch-containing foods to aid in the preservation of starch functionality. One step could involve heat treating honey with other ingredients, especially those that dilute and acidify the honey environment.     

Detection and Partial Characterisation of New Anthocyanin-Derived Pigments in Wine

New anthocyanin-derived red–orange pigments were detected in wine in the course of cross-flow microfiltration experiments. Analysis of the sugar and organic acid released respectively by acid and alkaline hydrolysis showed that the two major products were respectively a glucoside and the corresponding p-coumaroylglucoside. Mass spectrometry indicated molecular masses of 755·5 for the p-coumaroylglucoside and of 447·5 for its aglycone. Therefore, the new pigments are likely to result from condensation reaction between grape anthocyanins (possibly the 3-glucoside and 3-p-coumaroylglucoside of malvidin) and another wine component, which is not a flavanol. This reaction may partici-pate in the mechanism of colour change during ageing of red wines.     

EFFECT OF SODIUM LAURYL SULFATE IN SOLUBILIZING PROTEIN FOR TRYPTOPHAN DETERMINATION

The solubilization of proteins in corn and sorghum, using sodium lauryl sulfate (NaLS) in a basic medium, was used for tryptophan determination. The experimental design evaluated different levels of sodium lauryl sulfate and sodium hydroxide, at various temperatures and times. Prior to treatment, the samples were dried, ground and defatted. These were hydrolyzed and tryptophan was quantified spectrophotometrically (λ_max= 565 nm). Casein was used as control and DL-tryptophan was used for generating the standard curve according to Beer's Law. From the results obtained, it was possible to conclude that sodium lauryl sulfate was very effective in solubilizing corn and sorghum protein for subsequent tryptophan determination.     

p-HYDROXYPHENYLACETIC ACID AND-3,4-DIHYDROXYPHENYLACETIC ACID AS SUBSTRATES FOR MUSHROOM TYROSINASE

The hydroxylation of p-hydroxyphenylacetic acid (PHPAC) and the oxidation of 3,4-dihydroxyphenylacetic acid (DOPAC) by mushroom tyrosinase are illustrated. DOPAC quinone (4-carboxy-methyl-o-benzoquinone (λ_max= 400±10 nm) is the initial pigmented product formed when DOPAC is oxidized by the enzyme. DOPAC quinone is very unstable, and, once formed, is converted rapidly to further oxidation product(s).
The relationships between the rate of p-dihydroxyphenylacetic acid hydroxylation and 3,4-dihydroxyphenylacetic acid oxidation as a function of various concentrations of each substrate and of mushroom tyrosinase, are described.
The effect of the addition of various chemicals that can potentially conjugate otherwise affect DOPAC quinone was studied The Km value of 3,4-dihydroxyphenylacetic acid for mushroom tyrosinase was estimated to be 4.0 mM.     

Formation of biopolymer-coated liposomes by electrostatic deposition of chitosan

ABSTRACT:  The purpose of this study was to prepare stable biopolymer-coated liposome suspensions using an electrostatic deposition method. Liposome suspensions were produced by homogenizing 1% soy lecithin in acetate buffer (0.1 M, pH 3). Cationic chitosan (Mw approximately 200 kDa) solutions were mixed with anionic liposome suspensions ( d approximately 100 and 200 nm), and the effect of phospholipid concentration, chitosan concentration, and liposome size on the properties of the particles formed was determined. The particle size and charge (ζ-potential) were measured using dynamic light scattering and particle electrophoresis. The particle charge changed from –38 mV in the absence of chitosan to +60 mV in the presence of chitosan, indicating complex formation between the anionic liposomes and cationic chitosan molecules. Below a minimum critical chitosan concentration ( c _min), large aggregates were formed that phase separated within minutes, whose origin was attributed to formation of coacervates. On the other hand, above a maximum critical chitosan concentration ( c _max), large flocs were formed that sedimented within hours, whose formation was attributed to depletion flocculation. Minimum and maximum critical chitosan concentrations depended on liposomal concentration and size. At c _min < c < c _max, chitosan-coated liposomes were formed that did not aggregate and were stable to sedimentation. Coated liposomes had better stability to aggregation than uncoated liposomes when stored at ambient temperatures for 45 d. This study indicates that chitosan can be used to form biopolymer-coated liposomes with enhanced stability over uncoated liposomes.     

Surfactant-induced fluorescence changes in fluorescein dye

Addition of non-ionic surfactants revealed changes in the visible absorbance and fluorescence characteristics of fluorescein dyes. Non-ionic surfactants induced a shift in Δ_max, towards shorter wavelengths along with a decrease in absorbance of the dye. On the other hand, addition of anionic surfactants induced a shift of Δ_max, towards longer wavelengths along with enhancement in absorbance and fluorescence. The absorbance value decreased initially, but increased on further addition of cationic surfactant, whereas fluorescence increased initially but decreased on further addition of cationic surfactant. These changes are attributed to the interaction of surfactant micelle with dye molecules, resulting in change of the coloured quinoid form to the colourless lactone form and vice versa.     

Modeling the Growth Inhibition Kinetics of Baker's Yeast by Potassium Sorbate Using Statistical Approaches

Potassium sorbate is widely used as a preservative in food products. The inhibition kinetics of yeast growth by potassium sorbate was determined in order to predict the inhibition mechanism and develop an antimicrobial activity model. Linear regression resulted in uncompetitive growth inhibition using different concentrations of nutrients in liquid media containing yeast extract, malt extract (YM broth) and potassium sorbate. At 30°C, constant K_s of YM broth to yeast was 0.254%, maximum growth rate (μ_max) of yeast was 0.008 min^-1, and inhibition constant (K_i) of potassium sorbate to yeast growth was 0.324%. This statistical method could reliably determine the growth inhibition mechanism and kinetics.     

Auto-Oxidation of Extractable Color Pigments in Chili Pepper with Special Reference to Ethoxyquin Treatment

SUMMARY— Deterioration of extractable color pigments in dehydrated, ground chili peppers during storage was shown to be an auto-oxidative process having the kinetics of a second order reaction. Consequently, the reaction rate constant, k₂₁ was used to evaluate the effect of a number of variables, such as moisture content, storage atmosphere and ethoxyquin treatment. In an oxygen-containing atmosphere, the rate constants for color deterioration varied with moisture content. The k₂ value was 2 to 3 times higher at 4 to 5% moisture content than at 8 to 9%. Treatment with 100 ppm ethoxyquin afforded both substantial protection against color deterioration and an improvement of the surface color of the paprika in storage. Such treatment was most effective in low-moisture chili peppers. The color stability of several varieties was compared under controlled conditions. Some varieties were found to be more stable than others.     

PROPERTIES OF BIXIN AND NORBIXIN AND THE COMPOSITION OF ANNATTO EXTRACTS

SUMMARY— The melting point and ₁ ^1% _cm-values of a-bixin, β-bixin, and a-norbixin were determined and the stability of a-bixin examined under different conditions. The total pigment content of butter colors was determined. a-Bixin was the principal pigment; in addition, at least eight different pigments were present. The content of a- and β-bixin in butter colors was also determined. Because of complex formation of bixin and norbixin with a yellow pigment, the simple chromatographic method became rather laborious. This complex formation did not occur in the annatto suspensions in oil and fat. These preparations were more concentrated, while the amount of decomposition products of a-bixin was relatively slight. The stability of the pigments in butter colors appeared to be great. Investigation of annatto cheese colors showed that these extracts contain at least seven color components. The total amount of red pigment and the principal pigment a-norbixin were determined.     

天然彩色茧丝纤维的丝胶固着技术研究

为更多保留天然彩色茧丝纤维丝胶中的色素,采用乙烯单体接枝和戊二醛交联相结合的方法对黄红色天然彩色茧丝进行处理,研究了交联和接枝处理以及接枝和交联次序对天然彩色茧丝增重率和色泽的影响。研究结果表明:交联和接枝处理增强了丝胶间或与丝素的结合力,能较好地保留天然彩色茧丝丝胶内的色素成分;而颜色的饱和度较未处理丝纤维低,颜色变暗,色调偏向绿光;先交联工艺对纤维K/S值和颜色特征值的影响较小,是一种较好的处理方法。