Decolorization of Brown Pigments in Foods by Immobilized Mycelia of Coriolus versicolor IFO 30340 and Paecilomyces canadensis NC-1

Three microorganisms were cultured to investigate their decolorizing activity on mixtures of 2 types of model brown pigment and 2 types of browned food. The mixture of model brown pigments of the Maillard reaction type and phenol type was not decolorized by cultivation with Coriolus versicolor IFO 30340, but it was decolorized by Paecilomyces canadensis NC‐1 and by Streptomyces werraensis TT 14. The immobilized mycelia of C. versicolor IFO 30340 and P. canadensis NC‐1 were incubated simultaneously or successively with each mixture of 2 types of browned food. It was found that the mixed culture of these 2 mycelia showed a higher decolorization rate than their successive culture.     

Characterization of the brown pigment in sautéed onion by metal-chelating Sepharose 6B column chromatography and microbial decolorization

The brown pigment in sautéed onion was characterized by a microbiological procedure (involving microbial decolorization) and a chemical procedure (involving metal-chelating chromatography with a Sepharose 6B column). The suitability of the chemical procedure as a method for classifying brown pigments was also examined.The pigment from sautéed onion was about 40% decolorized by Coriolus versicolor IFO 30340, as were the model pigments caramel and model melanoidin (MM). The phenol-type model pigments (PTMP) were approximately 40-60% decolorized by Paecilomyces canadensis NC-1, but the sautéed-onion pigment, the MM and the caramel were merely 5% decolorized by it. The pigment from sautéed onion was separated into two components by Cu²⁺, Fe²⁺, or Zn²⁺-chelating chromatography, as were caramel and MM; the PTMP was not separated into multiple components by either Cu²⁺ or Fe²⁺-chelating chromatography. The results from both methods indicate that the pigment from sautéed onion is similar to MM and caramel but not the phenol-type pigment.     

Effect of Hydrogen Peroxide and Phenolic Compounds on Horseradish Peroxidase-Catalyzed Decolorization of Betalain Pigments

The effect of hydrogen peroxide and phenolic compounds on the decolorization of betanin and a betaxanthin preparation by horse-radish peroxidase (HRP) was examined. Betanin was decolorized at a greater rate than the betaxanthm pigments and both reactions were H₂O²-dependent. Betaxanthin was more prone to oxidatic decolorization than betanin. 2,4-Dichlorophenol, resorcinol and o-toluidine stimulated the decolorization of both pigments. Guaiacol enhanced the peroxidatic decolorization of both pigments to a small extent, but inhibited the oxidatic breakdown of betaxanthin. Possible implications of these results are discussed.     

Decolorization of heat-treatment liquor of waste sludge by a bioreactor using polyurethane foam-immobilized white rot fungus equipped with an ultramembrane filtration unit

A bench-scale bioreactor using immobilized fungal cells equipped with an ultramembrane filtration unit was developed as a means of decolorizing brown color components (melanoidins) arising from the heat-treatment liquor (HTL) of waste sludge. Artificial HTL containing 4200 color units of synthetic melanoidin supplemented with 1000 mg/l ethanol was first subjected to decolorization by the fungus Coriolus hirsutus IFO4917 immobilized onto polyurethane foam cubes. Then, the resultant biologically treated HTL was subjected to ultrafiltration to obtain the permeate (filtrate) as the effluent. The retentate (concentrate) of the filtration unit, containing the remaining melanoidin of high molecular weight and extracellular decolorizing enzymes, was returned to the fungal bioreactor to allow further decolorization. This system was operated in a sequencing batch mode under nonsterile conditions. Contamination of the bioreactor with air/water-born microbes markedly lowered the decolorization efficiency. However, this problem was solved by heating the returned concentrate at 50 degrees C for 10 min. Under the almost stable condition of a hydraulic retention time of 2 d in a 1-d cycle sequencing batch mode, about 70% decolorization was routinely achieved using the entire system (bioreactor + ultrafiltration), while the contribution of the fungal bioreactor alone to the decolorization was about 45%.     

Anthocyanins and other polyphenolics in American elderberry (Sambucus canadensis) and European elderberry (S. nigra) cultivars

BACKGROUND: Ten genotypes representing two elderberry species, Sambucus canadensis L. (eight genotypes) and S. nigra L. (two genotypes), were examined for their anthocyanins (ACY), total phenolics (TP),°Brix, titratable acidity (TA), and pH over two growing seasons. RESULTS: Overall, fruit generally had higher ACY, TP, ACY/TP,°Brix, and pH in 2005 than 2004. All samples of S. canadensis had similar anthocyanin profiles to one another, but were distinctly different from S. nigra. Both species had cyanidin‐based anthocyanins as major pigments. Previously unreported anthocyanins were identified in some samples in this study. Trace levels of delphinidin 3‐rutinoside were present in all elderberry samples except cv. ‘Korsør’. Also, petunidin 3‐rutinoside was detected in cvs ‘Adams 2’, ‘Johns’, ‘Scotia’, ‘York’, and ‘Netzer’ (S. canadensis). The identified polyphenolics of both species were mainly composed of cinnamic acids and flavonol glycosides. The major polyphenolic compounds present in S. canadensis were neochlorogenic acid, chlorogenic acid, rutin, and isorhamnetin 3‐rutinoside, while chlorogenic acid and rutin were found to be major polyphenolic compounds in S. nigra. CONCLUSION: Sufficient variability was seen among these genotypes to suggest that a successful breeding program could be carried out to improve levels of the various compounds evaluated in this study. Copyright © 2007 Society of Chemical Industry     

The protective effects of melanoidins in adriamycin‐induced oxidative stress in isolated rat hepatocytes

The importance of the antioxidants contained in foods is well recognized both for preserving the foods themselves and for supplying essential antioxidants in vivo. Among these, the melanoidins formed during food processing and storage represent a significant part of our diet, with an average intake of several grams per day. Melanoidins exhibit antioxidant properties in vitro through their protective effect against reactive oxygen species. Here we investigated the protective effect of the model glucose–glycine melanoidins on oxidative stress induced by adriamycin in hepatocytes isolated from rats. The study was performed by examining cell toxicity (lactate dehydrogenase) release in the medium, lipoperoxidation, protein oxidation, GSH and ATP levels. The addition of 50 µg glucose–glycine melanoidins to the hepatocytes treated with 25 and 75 µM of adriamycin decreased the cell oxidative damage. The cell toxicity, lipoperoxidation and the protein oxidation decreased significantly in the presence of melanoidins. The effect of melanoidins on the intracellular antioxidant GSH when co‐incubated the adriamycin–hepatocytes with melanoidins resulted in a recovery of GSH levels. Furthermore, from the study of ATP levels we found that the damage to the mitochondria induced by adriamycin is decreased in the presence of melanoidins. According to these results, we suggest that melanoidins are capable of preventing cell oxidation. Based on these mechanisms, the ingestion of melanoidins present in food could be play a role important in the prevention of oxidative damage and prevention the diseases related to free radicals. Copyright © 2004 Society of Chemical Industry     

Stability of pigments and oil in pistachio kernels during storage

This work tested the stability of pigments (chlorophyll [chl] a and chlorophyll [chl] b, and lutein] and oil in pistachio kernels stored up to 14 months at three different temperatures: 10, 25 and 37 °C. The samples were hermetically packaged using two films (nylon and ethylene vinyl alcohol) with and without oxygen scavengers. For each temperature, reference samples were packaged in open bags. For both the oil and pigments, no differences were observed during storage, irrespective of packaging or oxygen scavengers. After 14 months, the oil showed very few changes: a slight increase in acidity and peroxide value (PV) irrespective of storage temperature; the spectrophotometric indices K₂₃₂ and K₂₆₈ remained the same. As for pigment stability, the lowest concentrations were observed at 37 °C with a degradation of about 62% for chl a, 44% for chl b and 57.5% for lutein. At 10 and 25 °C, the samples showed slight differences, the pigments degradations were about 46% for chl a, 33% for chl b and 37% for lutein. The degradation rate constants for the three pigments fitted a pseudo‐zero‐order kinetic in which Ea was 11.7 kJ mol^?1, 12.1 kJ mol^?1 and 18.2 kJ mol^?1 for chl a, chl b and lutein respectively.     

Changes in carotenoids and chlorophylls in fresh green asparagus (Asparagus officinalis L) stored under modified atmosphere packaging

Asparagus is a highly perishable product owing to its high respiratory rate, a reason why modified atmosphere packaging (MAP) has been used in order to increase the shelf‐life of fresh asparagus. Carotenoid and chlorophyll pigments are important compounds for the maintenance of both the nutritional and sensory quality of asparagus. In this study, green asparagus spears were stored under refrigeration at 2 °C for 14 days, under MAP at 2 °C for 26–33 days and under MAP at 10 °C for 20 days. Pigment profiles were determined using high‐performance liquid chromatography (HPLC), with three classes of compounds being detected, namely oxygenated carotenoids (xanthophylls), hydrocarbonated carotenoids (carotenes) and chlorophylls. The xanthophylls identified were neoxanthin, violaxanthin, lutein and zeaxanthin. Only β‐carotene was detected in the carotene fraction. In the chlorophyll pigments, three molecules were isolated, chlorophyll b, its epimer chlorophyll b′ and chlorophyll a. Also detected were the first degradation products of chlorophylls, pheophytins b and a respectively. Modified atmosphere packaging at 2 °C was found to be effective in extending the shelf‐life for up to 4 weeks and in preserving the colour of fresh asparagus. Copyright © 2004 Society of Chemical Industry     

ANTIMICROBIAL ACTIVITY OF MELANOIDINS

Melanoidins are high molecular weight compounds formed during the final stage of the Maillard reaction. Melanoidins have been studied in recent years because of their nutritional, biological and health implications, apart from their role on the stability during processing and shelf life of foods. A fast and robust microtiter plate‐based assay for a quantitative screening of the antimicrobial activity of melanoidins was applied. Oxytetracyclin was used as reference for assessing the antimicrobial activity of different melanoidins isolated from model systems. The minimum inhibitory concentration was calculated, and activity was related to the antimicrobial activity of an oxytetracyclin solution (100 µg/L). Glucose–lysine melanoidin exerted the highest antimicrobial activity, being at a concentration of 1 mg/mL, equivalent to an oxytetracyclin solution of 170 µg/L.     

Isolation,identification, and decolorization capabilities of strain ZW-4 for Pigment Red 23

A strain ZW-4 with remarkable ability to decolorize the Pigment Red 23 was isolated from aerobic sludge by the method of concentration gradient domestication. The strain was identified as Prototheca sp. according to its morphological characters and 16S rDNA sequence analysis. Experiments on the effect of decolorization conditions were carried out under aerobic conditions. The results showed that the best nutrient source was yeast powder, and the optimum conditions were 1% yeast powder, 5% inoculum, pH 7.5, temperature 35 °C, and salinity less than 4%. Under these conditions, the decolorization rate of Pigment Red 23 (initial concentration of 100 mg L^?1) was more than 91% when the strain ZW-4 was cultivated for 18 h. The strain also showed better salt tolerance property, which ranged from 6 to 8%. Besides, spectrophotometric analysis demonstrated that the decolorization mechanism of Pigment Red 23 was mainly biological degradation. Furthermore, toxicity tests indicated that the toxicity of Pigment Red 23 after decolorization had reduced noticeably with the strain ZW-4.     

Application of capillary zone electrophoresis to the study of food and food-model melanoidins

Different water soluble melanoidins have been isolated from both heated (100 °C/24 h) carbohydrate/amino acid model systems and medium-roasted coffee. Capillary zone electrophoresis (50 mM sodium tetraborate, pH 9.3) has been applied to determine the saturated or aromatic character of the isolated melanoidins. Melanoidins obtained from different solutions after an equivalent heating treatment possess similar apparent molecular weight but different charge/mass ratio, suggesting differences in their degree of saturation. Melanoidins isolated from model systems containing lysine showed a lower saturation than those isolated from either coffee or other model systems containing glycine, alanine or tryptophan. Depending on the type of amino acid as reactant, melanoidins could be mainly constituted by a stable structure or common core which is changing according to the thermal conditions applied through a more saturated structure.     

Stability Modeling of Red Pigments Produced by Monascus purpureus in Submerged Cultivations with Sugarcane Bagasse

Monascus purpureus red pigments were produced in submerged cultivations employing sugarcane bagasse (SB) as carbon source in combination with various nitrogen sources. Peptone and soy protein isolate (SPI) as nitrogen sources generated the best pigment yields. NH₄Cl has not supported high pigment production. Red pigments produced using SB and SPI as growth substrates were submitted to temperature and pH stability analysis. Data from thermal pigment degradation were fitted to five mathematical models, and a first-order equation was accepted as the best one to describe color decay. Red pigments showed high stability at low temperatures (30–60 °C) and at near-neutrality pH values (6.0–8.0) when compared to that at high temperatures (above 60 °C) and at acidic pH values (4.0–5.0). Monascus pigments produced using a low-cost agroindustrial waste (SB) as carbon source could be utilized as colorants in foods and foodstuffs manufactured under mild process conditions.     

Effects of roasting conditions on the physicochemical properties and volatile distribution in perilla oils (Perilla frutescens var. japonica)

Abstract: Perilla seeds have more than 60% of α‐linolenic acid, one of omega‐3 essential fatty acids. Headspace volatiles and physicochemical properties including color, fluorescence intensity, and the oxidation products in perilla oil (PO) from perilla seeds roasted at different conditions were analyzed. Roasting temperature was 150, 170, 190, and 210 °C, and roasting time was 15 and 30 min at each roasting temperature. PO from higher roasting temperature and longer roasting time had lower L* values, higher a*, b*, and chroma values, more brown pigments and fluorescence intensity, and more conjugated dienoic acids. Pyrazines were major volatiles in PO, and furans, sulfur‐containing compounds, and hydrocarbons were also detected by a solid phase microextraction gas chromatography/mass spectrometry. In PO, 2,5‐Dimethylpyrazine and 2‐furancarboxaldehyde were 2 major volatiles. The principal component analysis of volatiles showed the 1st principal component (PC1) and the 2nd principal component (PC2) express 56.64% and 22.72% of the volatile variability in PO, respectively, which can differentiate PO prepared from roasting conditions clearly. Some physicochemical properties especially brown pigment and volatiles were positively correlated with each other in PO. Practical Application: Perilla oil (PO) from perilla seeds possesses more than 60% of α‐linolenic acid, one of omega‐3 fatty acids. Roasting process has been used to extract oil from perilla seeds. Understanding physicochemical properties of PO from diverse roasting conditions are important steps to produce PO in food industry. Roasting process induces darkening of color, increase of fluorescence intensity, and brown pigments in PO. Pyrazines and furans are major headspace volatiles in PO roasted above 170 °C. The results of this study can help to produce PO in industrial scales with desired headspace volatiles, colors, and oxidative state.     

Growth of Listeria monocytogenes in refrigerated ready-to-eat foods in Japan

The ability of L. monocytogenes to grow in a series of Japanese ready-to-eat (RTE) foods, including boiled baby sardine and Japanese pickle, was tested at two different refrigeration temperatures. In RTE foods in which L. monocytogenes can grow, growth was significantly higher at 10°C than that at 4°C during their shelf lives and growth patterns varied extensively among the different types of foods. However, growth did not occur at 4°C within the shelf life of certain RTE foods, such as broiled squid. The patterns of growth were varied extensively with different sample types. These results suggest that some types of traditional Japanese RTE foods stored at 10°C may be potential sources of listeriosis. To reduce the risk of food-borne listeriosis, studies to determine the contamination levels in RTE foods and the effects of storage temperature on their shelf lives are needed.     

Modeling Growth Rate and Assessing Aflatoxins Production by Aspergillus flavus as a Function of Water Activity and Temperature on Polished and Brown Rice

Abstract: The aim of this study was to model the radial growth rate and to assess aflatoxin production by Aspergillus flavus as a function of water activity (a_w 0.82 to 0.92) and temperature (12 to 42 °C) on polished and brown rice. The growth of the fungi, expressed as colony diameter (mm) was measured daily, and the aflatoxins were analyzed using HPLC with a fluorescence detector. The growth rates were estimated using the primary model of Baranyi, which describes the change in colony radius as a function of time. Total of 2 secondary models were used to describe the combined effects of a_w and temperature on the growth rates. The models were validated using independent experimental data. Linear Arrhenius–Davey model proved to be the best predictor of A. flavus growth rates on polished and brown rice followed by polynomial model. The estimated optimal growth temperature was around 30 °C. A. flavus growth and aflatoxins were not detected at 0.82 a_w on polished rice while growth and aflatoxins were detected at this a_w between 25 and 35 °C on brown rice. The highest amounts of toxins were formed at the highest a_w values (0.90 to 0.92) at a temperature of 20 °C after 21 d of incubation on both types of rice. Nevertheless, the consistencies of toxin production within a wider range of a_w values occurred between 25 to 30 °C. Brown rice seems to support A. flavus growth and aflatoxin production more than the polished rice. Practical Application: The developed models can be used to estimate to what extent the change in grain ecosystem conditions affect the storage stability and safety of grains without the need for running long‐standing storage study. By monitoring the intergranular relative humidity and temperature at different locations in the storage facility and inputting these data into the models, it is directly possible to assess either the conditions are conductive for the growth of A. flavus or aflatoxin production.     

Growth or Survival of Listeria monocytogenes in Ready-to-Eat Meat Products and Combination Deli Salads During Refrigerated Storage

Growth or survival of Listeria monocytogenes in cold‐smoked salmon; sliced, cooked ham; sliced, roasted turkey; shrimp salad; and coleslaw obtained at retail supermarkets stored at 5 °C, 7 °C, or 10 °C (41 °F, 45 °F, or 50 °F, respectively) for up to 14 d was evaluated. Cold‐smoked salmon, ham, and turkey were obtained in case‐ready, vacuum packages. All food products were stored aerobically to reflect additional handling within the retail supermarket. Cold‐smoked salmon, ham, and turkey supported the growth of L. monocytogenes at all 3 storage temperatures. Fitted growth curves of initial populations (about 3 log₁₀ colony‐forming units [CFU]/g) in cold‐smoked salmon, ham, and turkey stored at 5 °C achieved maximal growth rates of 0.29, 0.45, and 0.42 log₁₀ CFU/g growth per day, respectively. Storage at 10 °C increased the estimated maximal growth rate of the pathogen by 0.56 to 1.08 log₁₀ CFU/ g growth per day compared with storage at 5 °C. A decline in populations of L. monocytogenes was observed in shrimp salad and coleslaw, and the rate of decline was influenced by storage temperature. Retention of viability was higher in shrimp salad than in coleslaw, where populations fell 1.2, 1.8, and 2.5 log₁₀ CFU/g at 5 °C, 7 °C, and 10 °C, respectively, after 14 d of storage. Inability of shrimp salad and coleslaw to support the growth of L. monocytogenes may be attributed to the acidic pH (4.8 and 4.5, respectively) of the formulations used in this study. Results show that the behavior of L. monocytogenes in potentially hazardous ready‐to‐eat foods is dependent upon the composition of individual food products as well as storage temperature.     

Synthesis of raffinose by fungal α-galacotosidase from Absidia corymbifera

In order to investigate the optimal conditions for raffinose synthesis, α-galactosidase was purified from Absidia corymbifera IFO8084 with a recovery yield of approximately 8.1% (8.36 mg). The molecular weight of the wild-type α-galactosidase was about 83 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The native molecular mass of the enzyme was approximately 330 kDa by gel filtration chromatography, indicating that α-galactosidase from A. corymbifera IFO8084 is a homotetrameric enzyme. The purified enzyme displayed optimal enzyme activity at pH 4.5 and 60°C. When the purified α-galactosidase was incubated in a substrate solution of sucrose and D-galactose for 48 hr at 37°C, raffinose was synthesized and was confirmed by thin layer chromatography (TLC), high performance liquid chromatography (HPLC), and ¹³C-nuclear magnetic resonance (¹³C-NMR) spectrometer analysis. Maximum rates of conversion were observed with 1.67 M galactose, 2.04 M sucrose, and 100 U α-galactosidase at pH 6.0 and 70°C. Under the optimized conditions, the overall conversion ratio was 10%(w/v), representing 2.5 times the synthesis yield that would be possible without the optimized conditions.     

Characterization of a new isolate of Lactobacillus fermentum IFO 3956 from Egyptian Ras cheese with proteolytic activity

More than 200 isolates were obtained from 15 Egyptian traditional dairy products (Domiatti cheese, Ras cheese and Rayeb milk) collected from local markets of Alexandria, Tanta and Kafr El-Sheikh. Examination with optical microscope of these dairy samples allowed to classify 92 bacilli, 64 of which were identified as lactobacilli. The proteolytic activity of lactobacilli isolates was tested on skim milk agar. Eight isolates showing a high proteolytic activity were further tested on UHT skim milk. The strain showing the highest proteolytic activity was purified and identified as Lactobacillus fermentum IFO 3656. The specific proteolytic activity of this strain and the factors affecting it (pH, temperature and presence of inhibitors) were studied. The proteolysis targeted mainly caseins (73% of whole casein), especially β-casein (85%). Smaller portions of whey proteins were proteolyzed (20%) essentially β-lactoglobulin. The proteolysis process gave rise to medium-sized peptide populations. The optimum conditions for the proteolysis activity of the studied strains were pH 6.5 and 37 °C. Proteolytic activities were very slightly affected by the increase of the temperature to 42 °C or the pH to 8.2. The protease system of Lactobacillus fermentum IFO 3956 is most probably composed from a high amount of metalloproteases and small amount of cysteine and serine proteases.     

Color and Pigment Stability of Red Radish and Red-Fleshed Potato Anthocyanins in Juice Model Systems

Color and pigment stability of model juices (pH 3.5) were evaluated during 65 wk of storage at 2°C and 25°C in the dark. Two acylated pelargonidin-based anthocyanins, red-fleshed potatoes (Solanum tuberosum) and red radishes (Raphanus sativus), and 2 extraction methods, C-18 resin and juice processing, were used and compared to FD&C Red #40. Color (CIELch) and pigment degradation depended on storage temperature, anthocyanin structure and extraction method, with chemically extracted radish anthocyanins showing the best overall stability. At room temperature (25°C), higher stability was obtained with C-18 purified radish anthocyanins (22 wk half-life) and lowest with potatojuice concentrate (10 wk half-life). Refrigeration increased the half-life of pigments to over a year.     

Desulphiting dried apricots by exposure to hot air flow

Sulphited dried apricots were exposed to hot air flows at 40, 50 and 60 °C and the removal of SO₂ was investigated as their moisture content fell from an initial value of 193.2 g kg^?1 to a final value of 80–90 g kg^?1. A first‐order kinetic model was found for the removal of SO₂ between 40 and 60 °C. Temperature quotients (Q₁₀) for the removal of SO₂ were 2.84 between 40 and 50 °C and 4.93 between 50 and 60 °C; the activation energy (E_a) was 114.40 kJ mol^?1 between 40 and 60 °C. Analysis of the kinetic data also suggested a first‐order reaction for non‐enzymatic browning, with Q₁₀ values of 2.34 between 40 and 50 °C and 5.36 between 50 and 60 °C and an E_a value of 109.36 kJ mol^?1 between 40 and 60 °C. Exposure of dried apricots to a 60 °C air flow resulted in a rate constant for brown pigment formation that was 12 and 5 times higher than those at 40 and 50 °C respectively. © 2002 Society of Chemical Industry