Hunter Color Parameters Research Articles

Studies on functional, thermal and pasting properties of flours from different chickpea ( Cicer arietinum L.) cultivars

The variability in physicochemical, functional, thermal, and pasting properties of flours from five desi (PBG-1, PDG-4, PDG-3, GL-769 and GPF-2) and one kabuli type (L-550) chickpea cultivars were studied and related to each other. Physicochemical (water solubility index, water absorption index, hunter colour parameters and bulk density) and functional properties (water absorption, oil absorption, least gelation concentration, foaming, and emulsification properties) of desi and kabuli chickpea flours were determined. Significant differences between properties of flours from kabuli and desi chickpea cultivars were observed. Flour from kabuli chickpea cultivar was significantly different from desi chickpea flours in its highest L ∗, Δ E value, bulk density, oil absorption capacity, and emulsion stability. The kabuli and desi chickpea flours showed significant differences in transition temperatures ( T o, T p, and T c) and enthalpy of gelatinization (Δ H gel). T o, T p, T c and Δ H gel of chickpea flours ranged from 65.4 to 67.9, 70.6 to 73.3, 77.0 to 79.4 °C, and 3.5 to 4.9 J/g, respectively. L-550 flour (kabuli type) differed significantly from all other chickpea flours in exhibiting lowest T o, T p, T c, Δ H gel, and PHI. Pasting properties of chickpea flours, measured using a rapid visco analyzer (RVA), also differed significantly. Pasting temperatures, peak, final and setback viscosities of flours from different chickpea cultivars ranged from 73.1 to 75.2 °C, 112.3 to 180.3, 126.3 to 225.3, and 19.8 to 62.8 Rapid Visco Units (RVU), respectively. Kabuli chickpea flour showed a low pasting temperature (73.9 °C), and highest peak (180.3 RVU), trough (162.5 RVU), final (225.3 RVU), and setback (62.8 RVU) viscosities.

Change in colour and rheological behaviour of sunflower seed oil during frying and after adsorbent treatment of used oil

Improvement in colour and viscosity of used sunflower seed oil was studied because the reuse of recovered oil could provide considerable savings to food processors. In this study, 50 consecutive deep-fat fryings were done by using potato samples in sunflower seed oil at 170 °C. Significant changes in sunflower seed oil were observed during frying. Change in viscosity and Hunter colour parameters were investigated. These parameters were determined on oil samples taken periodically during frying, and after adsorbent treatment. A predetermined optimum adsorbent mixture (2% pekmez earth, 3% bentonite and 3% magnesium silicate by weight) was applied for colour and viscosity recovery of used oil. Both the adsorbent-treated and untreated used oils showed Newtonian behaviour. Significant increase in oil viscosity was observed during frying. Frying caused a decrease in Hunter L value and an increase in a, b and TCD values of used oil samples. Adsorbents improved the Hunter L, a and b values significantly as well as TCD values, but not the viscosity of the used oil. All the Hunter parameters and TCD followed zero order reaction kinetics. Good agreement was observed between calculated and measured data (r=0.986–0.996).

Effect of concentration and drying processes on color change of grape juice and leather (pestil)

The Hunter color parameters (L,a,b) of grape juice during boiling, cooking and of pestil samples (1.53 mm) during drying were investigated. It was found that most of the color changes occurred during grape juice boiling. However, during hot air or sun drying only the Hunter a-value changed. The reaction associated with color change followed zero-order reaction kinetics. The temperature dependence of the reaction rate constant was described by an Arrhenius-type equation.

Effect of drying method on the sorption characteristics of model fruit powders

Pectin-sugar gels were dehydrated with four different drying methods: freeze, microwave, vacuum and conventional drying to a moisture content of about 5%. The effect of the drying method on the water sorption properties of dehydrated products was evaluated at 25 °C. Freeze-dried gel adsorbed more water vapour than microwave-dried gel, which had a higher sorption capacity than vacuum- and conventional-dried product. The sorption isotherms were in agreement with the reported shape for high sugar foodstuffs. Three different equations proposed in the literature (GAB, Oswin, Hasley) were used to fit the sorption data. The GAB equation gave the best fit to the experimental data. The porosity of the dehydrated products depended on the drying method, ranging between 0.2 and 0.5. Freeze- and vacuum-dried pectin developed the highest porosity, whereas the lowest porosity was obtained using conventional and microwave drying. Hunter colour parameters (L, a, b) also depended on the drying method. The colour of freeze- and vacuum-dried pectin was close to that of commercial pectin, while the colour of the conventional- and microwave-dried product changed significantly.

Effects of stocking density on colour characteristics and deposition of carotenoids in cultured Arctic charr ( Salvelinus alpinus)

The colour characteristics and deposition of canthaxanthin in cultured Arctic charr ( Salvelinus alpinus), stocked at 40, 50 and 75 kg/m 3, were studied. Hunter L, a, b values of fillets, as such, or in the homogenized tissues, and skin of fish varied significantly among density groups. For belly skin, the numerical values of Hunter colour parameters decreased with increasing stocking density. However, no correlation existed between the total carotenoid contents of fish skin and their Hunter L, a, b values. On the other hand, the Hunter L values of fillets and homogenized tissues were inversely correlated with their carotenoid contents ( r = −0.9245 to −0.9844), whereas their Hunter a and b values were directly correlated with carotenoid contents ( r = 0.9040 to 0.9824 for a and 0.9527 to 0.9924 for b). The content of carotenoids in fillets of charr generally increased with duration of feeding on a pigmented diet, but a decrease was noted in some cases after 16 weeks of experimentation. However, no correlation existed between stocking density and the content of fillet carotenoids ( r = −0.6034). Canthaxanthin, echinenone, 4′-hydroxyechinenone and lutein were identified in fish fillet and canthaxanthin was the main carotenoid present.

Preparation of hydrolysates from bovine red blood cells and their debittering following plastein reaction

Protein hydrolysates from bovine red blood cells were prepared using commercially available Alcalase. The best nitrogen recovery (69.2%) was achieved at a degree of hydrolysis (DH) of 25%. However, the product so obtained had a strong bitter taste (4.3 on a 5-point scale). At DH 16%, the nitrogen recovery was 65.9% and the bitter taste of product decreased (to 3.5). The hydrolysate contained 81.8% crude protein (N × 6.25), 2.4% moisture and 15.8% sodium chloride and had excellent solubility characteristics in water in the pH range 2.6–9.5. The Hunter colour parameters of the hydrolysate showed that good release of haem compounds during the process had occurred. Incorporation of hydrolysates (up to 3%) in meat model systems enhanced their cooking yield by about 5%. The protein efficiency ratio value of the hydrolysate was 3.7 as compared with that of beef (2.8), pork (2.5) and cod (2.5) proteins. However, low contents of isoleucine and sulphur-containing amino acids gave an essential amino acid index of 67.3 for the product. The bitterness of hydrolysate was reduced considerably by plastein reaction with diethyl ester of glutamic acid. The resultant product had a crude protein (N × 6.25) content of 96.3% and contained 30.6% of glutamic acid. The total free amino acid content in the product decreased from 18.6 mg g −1 hydrolysate to 1.85 mg g −1 plastein.

Correlation for pigment content through colour determination using tristimulus values in a green leafy vegetable, swiss chard

AbstractThe relationship between colour parameters of the chlorophylls and carotenoids in the green leaves of Swiss chard was studied. Using the Hunter colour parameters (L*, a*, b*, chroma and hue angle) we found a correlation coefficient r2 = 0.9264 for the chlorophylls and r2 = 0.8595 for carotenoids. The chlorophyll a, b plus chlorophyllide a, b extraction and the carotenoid extraction were carried out on the whole tissue using N,N‐dimethylformamide as solvent. Using between 10 and 50 mg tissue, the extractions with 3 ml solvent for 14–16 h at 4°C in darkness were quantitative for the chlorophylls; for the carotenoids, the same procedure indicated a content approximating to the level of provitamin A present in the leafy vegetable.

Seal Meat – A Potential Source of Muscle Food: Chemical Composition, Essential Amino Acids and Colour Characteristics

Meat from harp seal (Phoca groenlandica) carcasses was separated by manual or mechanical deboning. The yield by manual separation of meat from dressed carcasses was 22–30% and this was increased to 80–88% by mechanical deboning. Crude protein content of the samples varied between 21.58–24.32% and this included a total hemoprotein content ranging from 5.28–9.08%. The content of total lipids, ash and collagen in the mechanically separated seal meat was higher than those in the manually separated samples. The content of essential amino acids in seal meat was generally higher or equal to those in beef and pork. The Hunter colour parameters of raw seal meat samples were L = 14.4–17.2, a = 2.0–5.2 and b = 0.9–2.2, thus reflecting the dark colour of the muscles.

Germination of Amaranth Seeds: Effects on Nutrient Composition and Color

ABSTRACTAmaranth seeds were germinated at a water activity of about 0.92 for up to 72 hr. Crude protein, true protein and crude fiber were found to increase and fat content to decrease. For 48 hr of germination reactive lysine values did not change. At 72 hr, a slight decrease was observed in lysine and in vitro protein digestibility was similar to the control. During germination Hunter color parameters L were lowered and a and b were enhanced. Germinated seeds showed a pinky color which appeared very attractive for various food uses.

Anthocyanin Pigment, Nonvolatile Acid, and Sugar Composition of Red Raspberry Juice

Abstract Liquid chromatographic methodology for determination of red raspberry anthocyanin pigments, nonvolatile acids, and sugars was developed and applied to authentic juices pressed in our pilot plant as well as to samples of European origin. Sugar analysis utilized an Aminex HPX-87C column; the mean contents of sucrose, glucose, and fructose were 0.17,2.59, and 2.97 g/100 mL, respectively. Citric, malic, and isocitric acids were best quantitated on two C-18 columns in series with refractive index detection; the mean content of citric, malic, and isocitric acids was 21.0 g/L, 872 mg/L, and 158 mg/L, respectively. Anthocyanins were resolved with high selectivity on a C-18 column using 15% acetic acid as organic modifier. The mean values for individual anthocyanins were: cyanidin-3-sophoroside, 74.2%; cyanidin-3-gIucoside, 12.2%; cyanidin-3-glucorutinoside, 8.6%; cyanidin-3-rutinoside, 1.7%; and pelargonidin-3-sophoroside, 2.9%. Anthocyanin pigment content ranged from 23.8 to 101.0 mg/100 mL. Carbon stable isotope ratios ranged from -23.2 to —24.7%o with a mean of -24.1%o. Additional data include color density, polymeric color, browning index, UV-visible spectra, pH, "Brix, tirratable acidity, and Hunter color parameters.

Cranberry Juice Composition

Abstract Eight samples of cranberries (Vaccinium macrocarpon) representing the major varieties and principal commercial growing regions in the United States were processed into juice. Four of the 8 samples were concentrated to 50° Brix. Liquid chromatography (LC) was used to determine nonvolatile organic acid, anthocyanidin pigment, and sugar profiles. Ultraviolet-visible spectral methods were used to determine anthocyanin concentration, polymeric color, and percent polymeric color. Other data presented include stable isotope carbon ratios, degree Brix, pH, and Hunter color parameters. These data are presented to serve as an authentic data base for use in detection of adulterated cranberry juice.

Color Degradation in an Ascorbic Acid‐Anthocyanin‐Flavanol Model System

ABSTRACTInteractions between ascorbic acid, pelargonidin‐3‐glucoside, and catechin were studied in pH 3.4 citrate‐phosphate buffer at 20°C under anaerobic and oxygenated conditions. Changes in anthocyanin pigment, ascorbic acid, dehydroascorbic acid, and catechin were quantitatively measured during 130 days storage along with Hunter color parameters, browning, and polymeric color. Ascorbic acid had a statistically significant effect on all parameters, including anthocyanin loss under both oxygen and nitrogen environments, catechin loss, increase in browning and polymeric color, decrease in Hunter “a” value and increase in Hunter L value. Ascorbic acid bleached anthocyanin pigment and also induced browning. There is evidence that anthocyanin pigment and ascorbic acid degrade through a direct condensation mechanism.

EFFECT OF MICROWAVE BLANCHING ON THE COLOR AND COMPOSITION OF STRAWBERRY CONCENTRATE

ABSTRACTThe influence of native enzymes on the color and composition of strawberry juice and concentrate was investigated through analyses of juice and concentrate which had been made from microwave‐blanched and from unheated fruit. Changes in anthocyanin (ACN) pigment, leucoanthocyanins, flavanols, total phenolics, ascorbic acid, and dehydroascorbic acid were monitored during 8 wk storage at 20°C; Hunter color parameters, polymeric color, and browning were also measured. Blanching results in improved color stability and has a protective effect on ACN pigments, reactive phenolics, and ascorbic acid. Blanched strawberry concentrate browns slower than the control. Monomeric ACN pigment undergoes rapid degradation to form polymeric pigments which are resistant to bisulfite bleaching.