Search

Milk packaged in glass bottles overwrapped with iridescent films (treatments blocked either a single visible riboflavin [Rb] excitation wavelength or all visible Rb excitation wavelengths; all treatments blocked UV Rb excitation wavelengths) was exposed to fluorescent lighting at 4 °C for up to 21 d and evaluated for light-oxidized flavor. Controls consisted of bottles with no overwrap (light-exposed treatment; represents the light barrier properties of the glass packaging) and bottles overwrapped with aluminum foil (light-protected treatment). A balanced incomplete block multi-sample difference test, using a ranking system and a trained panel, was used for evaluation of light oxidation flavor intensity. Volatiles were evaluated by gas chromatography and Rb degradation was evaluated by fluorescence spectroscopy. Packaging overwraps limited production of light oxidation flavor over time but not to the same degree as the complete light block. Blocking all visible and UV Rb excitation wavelengths reduced light oxidation flavor better than blocking only a single visible excitation wavelength plus all UV excitation wavelengths. Rb degraded over time in all treatments except the light-protected control treatment and only minor differences in the amount of degradation among treatments was observed. Hexanal production was significantly higher in the light-exposed control treatment compared to the light-protected control treatment from day 7; it was only sporadically significantly higher in the 570 nm and 400 nm block treatments. Pentanal, heptanal, and an unidentified volatile compound also increased in concentration over time, but there were no significant differences in concentration among the packaging overwrap treatments for these compounds. [ABSTRACT FROM AUTHOR]

Effects of fluorescent light, riboflavin, ascorbic acid, sodium azide, and butylated hydroxyanisole (BHA) on the volatiles in milk at 4 °C were determined using a combination of headspace-solid phase microextraction (HS-SPME), gas chromatography (GC), and mass spectrometry (MS). Pentanal, hexanal, heptanal, and dimethyl disulfide were formed only in the milk stored under light and increased significantly as the duration of light exposure increased from 0 to 8 h and the concentration of added riboflavin increased from 5 to 50 ppm ( P < 0.05). As fat content in milk increased, peak areas of pentanal, hexanal, and heptanal increased significantly ( P < 0.05) while those of dimethyl disulfide did not change significantly ( P > 0.05). Sodium azide prevented the formation of dimethyl disulfide in milk, implying that dimethyl disulfide can be formed through singlet oxygen oxidation (type II pathway). Addition of ascorbic acid and BHA reduced the formation of hexanal, heptanal, and dimethyl disulfide significantly ( P < 0.05). Generation mechanisms of pentanal seem to be different from those of hexanal and heptanal in milk. Both singlet oxygen oxidation (type II pathway) and free radicals (type I pathway) play important roles in the formation of light-induced volatiles in milk. [ABSTRACT FROM AUTHOR]

Singlet oxygen quenching activity of Trolox, a water-soluble derivative of tocopherol, was studied by electron spin resonance (ESR) spectroscopy in a buffer solution (pH 7.4) containing methylene blue (MB), 2,2,6,6-tetramethyl-4-piperidone (TMPD) after light illumination for 30 min. Trolox at the concentration of 125 μM quenched 89.1% singlet oxygen in the system. Trolox showed significantly higher singlet oxygen quenching activity than ascorbic acid in the buffer solution ( P < 0.05). Riboflavin in phosphate buffer solutions was degraded very fast under fluorescent light illumination. The photodegradation rate of riboflavin at pH 8.5 was significantly higher than pHs 4.5 and 6.5 ( P < 0.05). Lumiflavin was also degraded under the fluorescent light illumination, but its degradation rate was much lower than that of riboflavin under the same light intensity. Unlike riboflavin, the rate of lumiflavin photodegradation was the greatest at pH 4.5 and followed by pHs 6.5 and 8.5, in a decreasing order. Trolox greatly protected the photodegradation of riboflavin and lumiflavin. The protective activities of Trolox against the photodegradation of riboflavin and lumiflavin were also pH dependent. The treatments of 5 mM Trolox in the buffer solutions of pHs 8.5 and 6.5 exhibited 56.1% and 31.7% protection of riboflavin against degradation during 120 min light illumination, respectively. The treatments of Trolox at the concentrations of 1, 3, and 5 mM in the buffer of 6.5 exhibited 14.8%, 58.4%, and 81.4% protection of lumiflavin against degradation during 24 h light illumination, respectively. [ABSTRACT FROM AUTHOR]

The effect of rye flour extraction rates and baking on thiamine and riboflavin content, and antioxidant capacity of traditional rye bread were studied and compared with white wheat flour. The content of thiamine was higher (10.9%) in rye dough formulated with dark rye flour (F-100%; extraction rate of 100%) than in rye dough formulated with brown rye flour (F-92%; extraction rate of 92%) that was similar to dough made with wheat flour. The riboflavin content in rye dough made from flour F-100% was also higher (16%) than in dough formulated with flour F-92%, and both provided larger riboflavin content than wheat dough. Baking led to reductions in thiamine of 56% for wheat bread and of 20% for both rye breads; however, this process caused only a 10% decrease in riboflavin for wheat bread and a 30% decrease for rye breads. Trolox equivalent antioxidant capacity, peroxyl radical scavenging capacity, DPPH radical scavenging activity, and Folin–Ciocalteu reducing capacity were higher in rye than in wheat dough and bread. Baking process produced slight changes in antioxidant activity, except for Superoxide Dismutase-like activity where a sharp decrease was observed. Our findings showed that rye breads are an important source of B vitamins and rye breads formulated with dark and brown flours showed better antioxidant properties than wheat bread. Therefore, rye breads should be more widely recommended in human nutrition. [ABSTRACT FROM AUTHOR]

Effects of riboflavin photosensitization on the distribution of isoflavones in commercially available soymilk were analyzed using high-performance liquid chromatography (HPLC). Total isoflavones (TI) in soymilk with riboflavin (1000 ppm, w/v) under light were significantly different from those stored in the dark for 24 h ( P < 0.05), while TI in samples with 0 and 1000 ppm added riboflavin were not significant from each other in dark conditions ( P > 0.05). To test the effects of the concentration of riboflavin on TI, soymilk was mixed with riboflavin to make 0, 100, 250, and 500 ppm (w/v) and stored under light at 25 °C for 24 h. TI in soymilk with 100 ppm riboflavin under light significantly decreased by 13.5% for 24 h ( P < 0.05) compared to control samples and were not significantly different from those with 250 or 500 ppm samples ( P > 0.05). Daidzin and genistin were predominant isoflavones in soymilk, and the rate of photo degradation of genistin was higher than that of daidzin for 24 h in soymilk under riboflavin photosensitization. [ABSTRACT FROM AUTHOR]

Effects of photosensitizers including riboflavin, chlorophyll b, or methylene blue on the stability of daidzein and genistein were studied in model systems by high-performance liquid chromatography (HPLC). Concentration of daidzein and genistein in 80% methanol with riboflavin under light for 7 h was significantly decreased with the apparent 1st-order rate constants of 0.234 and 0.193/h, respectively, ( P < 0.05), while those without riboflavin under light did not change significantly ( P > 0.05). The stability of isoflavone aglycones in the dark did not change significantly irrespective of the presence of riboflavin ( P > 0.05). The concentrations of daidzein and genistein in chlorophyll b or methylene blue model systems under light were not significantly different from those in the dark for 7 h ( P > 0.05). Addition of sodium azide increased the stability of daidzein and genistein in riboflavin photosensitization with concentration dependent manner. However, the protective effects of β-carotene addition on the photodegradation of isoflavones were not high. The stability difference of daidzein and genistein in riboflavin photosensitization may be due to the high reactivity of riboflavin through type I pathway, although singlet oxygen may be involved in part. [ABSTRACT FROM AUTHOR]

The article discusses a study which aimed to determine the effect of riboflavin on the volatile compounds in soymilk during storage under light. The effects of ascorbic acid, a quencher for both the singlet oxygen and excited triplet riboflavin, on the formation of beany flavor compounds during the storage under light are also examined. The results show that riboflavin had significant effects on the headspace oxygen depletion and volatile compounds formation in soymilk under light.

The article discusses a study which aimed to determine the formation of singlet oxygen by riboflavin and the kinetics and mechanisms of riboflavin degradation in aqueous solution under photosensitization. The results show that singlet oxygen is involved in riboflavin destruction under light, explaining the extremely fast degradation of riboflavin in foods under light. It was also found that ascorbic acid and sodium azide reduce the degradation of riboflavin under light.

The photooxidation of ice cream containing 14.25% milk fat prepared from 7 fat materials with different compositions was investigated by conducting sensory evaluations for oxidized off-flavor and by monitoring hydroperoxide formation. They showed a wide range of oxidative stability against light, and the flavor score was related to peroxide value (correlation coefficient, 0.795). The photooxidative stability of ice cream was influenced mainly by the riboflavin content and by the oil's susceptibility to photooxidation. These contributing proportions were 53.7 and 17.6%, respectively, with a multiple regression model. The photooxidative stability of the oil fraction increased with the increasing tocopherol homologues ratio, γ-tocopherol/α-tocopherol (correlation coefficient, 0.846). Furthermore, the photooxidative stability of ice cream was influenced by the amount of free-fat content. [ABSTRACT FROM AUTHOR]

BSTRACT: A rapid method was developed for simultaneously determining thiamine, riboflavin, pyridoxine, nicotinamide, nicotinic acid, and ascorbic acid. It was tested on 15 samples. The peaks of all components were cleanly separated with good resolution by capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MECC). CZE was performed with 0.02 M borate buffer, and MECC was performed with 4% acetonitrile in 0.02 M borate/phosphate buffer containing 0.1 M sodium dodecyl sulfate. Average recoveries for all components were 80.3% to 103.7% with coefficients of variation being less than 5%. Thiamine, nicotinic acid, and pyridoxine contents were consistent with those labeled on the packages, but nicotinamide, riboflavin, and ascorbic acid contents of some samples were less. [ABSTRACT FROM AUTHOR]

Two infant milks claimed to have the same final composition in liquid and powdered form respectively were stored for 12 mo at 20, 30, and 37 °C. Vitamin E, thiamin, riboflavin, pyridoxine, folic acid, and nicotinamide remained constant at the three temperatures. However, there were statistically significant losses of vitamin A (approximately 35%) in samples stored at 37 °C. No differences were observed in vitamin stability between the two infant milks studied. Final levels of vitamin A were always higher than the minimum set by Spanish legislation. Vitamin A overfortification (approximately 200%) was more than that needed to compensate for losses during storage. [ABSTRACT FROM AUTHOR]

Examines the oxidation of vitamin D in a model of 12 percent water and 88 percent acetone in the presence of riboflavin under light and dark conditions, by means of measuring the depleted headspace oxygen. Effects of riboflavin on the oxidation process; Importance of vitamin D in the mineralization and growth of bones.

Examines the effects of riboflavin on anthocyanin synthesis using high anthocyanin producing leaf callus. Cells derived from suspended cultures of strawberry leaf tissues; Enhancement of anthocyanin synthesis; Peonidin-3-glucoside; Cyanidin-3-glucoside; Depression of cell growth by riboflavin.

BSTRACT Aluminum oxide was used to insolubilize (i.e. to lake) riboflavin 5′-phosphate (FMN) to improve the light stability of vitamin B2. HPLC was used to determine adsorption percentage and light stabilities of laked FMN. The adsorption of FMN on aluminum oxide was very effective. An FMN content of 55% in lake was achievable, with adsorption of 91%. The adsorption isotherm was of the Langmuir class, and differed from the desorption isotherm. The stabilities of laked FMN at different light intensities and aw values were significantly (p=0.05) higher than those of free FMN. [ABSTRACT FROM AUTHOR]

Porcine plasma inhibited iron-catalyzed lipid oxidation at the pH range (5.5-7.0) and temperatures (4-37°C) commonly found in food. Increasing concentrations of frozen-thawed plasma resulted in increased antioxidant activity until 100% inhibition was reached at 5.36 mg plasma protein/mL assay. In addition to iron, porcine plasma also inhibited hydrogen peroxide-activated hemoglobin- and photoactivated riboflavin-catalyzed lipid oxidation. The plasma partially lost antioxidant activity during refrigerator storage (4°C) after 8 days but not during frozen storage (~15°C) after 246 days. Dialyzing the plasma increased inhibition of iron-catalyzed lipid oxidation 1.8-fold higher than undialyzed plasma (1.5 mg plasma protein/mL). [ABSTRACT FROM AUTHOR]

BSTRACT Cowpea ( vigna unguiculuta) paste, the principal ingredient in akara, was evaluated to determine the influence of indigenous microflora on chemical characteristics associated with akara quality. Six formulas (with and without onion, salt and pepper), consisting of inoculated (indigenous microflora) and uninoculated pastes, were incubated for 24 hr at 30°C. A strong relationship between time of incubation and increase in titratable acidity was evident for all treatments. Nitrogen solubility and protein degradation increased during incubation. Monosaccharide content increased with incubation for all pastes, while diand oligosaccharides decreased. No significant changes in thiamin content were observed; however, riboflavin increased for all formulations as incubation progressed. [ABSTRACT FROM AUTHOR]

Retention of three water soluble B-vitamins in dry cowpeas cooked with a local tenderizer, named "kanwa," were investigated. Results showed cooking (100°C) in kanwa or sodium bicarbonate decreased levels and retention of vitamins compared to controls cooked in water. Levels of vitamins in kanwa-cooked cowpeas were not significantly different from those in NaHCO3 cooked samples. Retention in the alkaline cooking processes ranged 15-20% (thiamin), 26-49% (niacin) & 53-64% (riboflavin). Soaking followed by boiling at 100°C or pressure cooking (121°C) increased levels and retention of vitamins. [ABSTRACT FROM AUTHOR]

The article looks at industrial applications of selected studies published in the "Journal of Food Science." In one study, a group of Japanese researchers examined a novel method to shipping sterilized milk using a soft tank made from tarpaulin with high-pressure-resistant zippers. One study focused on the neuroprotective effects of astaxanthin and canthaxanthin in nerve growth factor differentiated PC12 cells. One study examined the changes of headspace volatiles in milk with riboflavin photosensitization.

Effects of riboflavin photosensitizations on the stability of bisphenol A (BPA), a well-known endocrine disrupting chemical, were studied in model and real-food systems by high-performance liquid chromatography (HPLC). Concentration of BPA was significantly decreased under light exposure ( P < 0.05) as the concentration of riboflavin increased while those without riboflavin under light or those with riboflavin in the dark did not change significantly ( P > 0.05). Addition of 50, 100, and 200 μM sodium azide significantly increased the stability of BPA in riboflavin photosensitization with concentration dependent manner ( P < 0.05), implying that a singlet oxygen or type II pathway played a role in the photodegradation of BPA. Stability of BPA in riboflavin was significantly increased in the presence of high concentration of tert-butanol, a hydroxyl radical quencher, under light storage for 80 min, indicating hydroxyl radicals were involved and contributed to the degradation of BPA, at least in part. Availability of riboflavin photosensitization on the photodegradation of BPA was tested in 2 canned tea beverages with different phenolic contents. BPA was more stable in the beverage sample with higher total phenolic contents and free radical scavenging ability. The photodegradation of BPA in riboflavin photosensitization can be an efficient way to decrease the concentration of BPA from environmental or food systems. [ABSTRACT FROM AUTHOR]

Milk fat whiteness is the key to the uniqueness of Western Australian milk. Following a controlled feeding regime, milk was collected fortnightly for 6 mo from 2 treatment groups: dryland and irrigation. The results showed that it was possible to produce high-quality milk with whiter fat by a controlled feeding regime and diet while maintaining the health of Holstein-Friesian cows. The reflectance method using infinite optical thickness showed milk fat color differences due to feed could be measured. After 8 wk of the study, milk fat from the dryland treatment was significantly whiter ( P < 0.05) than the irrigation treatment with area under curve total reflectance of 902.8 and 838.3, respectively. The official Japanese industry method, Agriculture and Livestock Industries Corp. (ALIC) butter tone, showed that from the 2nd to the 5th collections the color of milk fat from cows fed silage and grain (dryland treatment) was significantly whiter ( P < 0.01) with an average butter tone of 0.15 absorbance per gram compared to cows fed green pasture and grain (irrigation treatment) with a butter tone of 0.21 absorbance per gram. Protein and riboflavin levels also affect the whiteness of milk. The study followed the main feeding protocol of dryland dairies and suggests the majority of milk from Western Australia would receive a grade 1 classification, as dryland dairies dominate supply. [ABSTRACT FROM AUTHOR]

The article discusses the relationship between chemical reactions and stability of riboflavin in foods. According to the authors, riboflavin is relatively stable during thermal and nonthermal food processing and storage but is very light-sensitive. The authors conclude that riboflavin is an excellent photosensitizer for singlet oxygen formation and an excellent reactant for singlet oxygen.