COMBINED EFFECT OF pH AND HEAT TREATMENT ON DEGRADATION OF AFLATOXINS IN DRIED FIGS

Dried figs are sensitive commodities to aflatoxin contamination. Although preventive methods are the logical solution to aflatoxin problems, once the product is contaminated, decontamination procedures are inevitable. In this study, the effectiveness of a procedure consisted of acidification/alkalization, and heat treatment in degradation of aflatoxins was evaluated. The pH of dried fig extracts was adjusted to 3.1, 3.5, 6, 8 or 10 by adding acid or base. Extracts were heated at 50, 75 or 98C for 1 or 2 h, and then the residual aflatoxin B₁, B₂, G₁ and G₂ were determined. The highest level of degradation for aflatoxin B₁ (97  ±  1%) and B₂ (87  ±  1%) were observed at pH 10 in samples heated at 98 and 50C, respectively. Some treatments resulted in 100% degradation of aflatoxin G₁ and G₂ so that they could not be detected.

PRACTICAL APPLICATIONS

Aflatoxin contamination is a serious problem for a number of processed and non-processed foods, including dried figs. This not only presents severe risks to human and animal health but also causes economic problems for countries such as Turkey, U.S.A., Greece and Spain, which produce and export dried figs. It is clear that detoxifying studies are unavoidable when the amount of crop contaminated by toxins is considered. Therefore, the food industry is in search of applications that are effective in mycotoxin detoxification and adaptable to food processes. This is the first report on degradation of aflatoxins in naturally contaminated dried figs by such a promising method.     

EFFECT OF COMMERCIAL PROCESSING STAGES OF APPLE JUICE ON PATULIN, FUMARIC ACID AND HYDROXYMETHYLFURFURAL (HMF) LEVELS

The effects of different stages of commercial apple juice production on the patulin, fumaric acid and hydroxymethylfurfural (HMF) contents of apple juice were investigated. Heat treatment and activated charcoal were effective for the reduction of patulin. The average reduction of patulin were 13.4% and 22.9% for heat treatment and activated charcoal, respectively. Statistical analysis showed no significant differences (P<0.05) in the presence of fumaric acid between different treatments. Filtration and heat treatment caused an apparent increase in the HMF content, while activated charcoal caused a decrease. The average increments of HMF were 40.4% and 38.0% for separation and heat treatment, respectively, while the average reduction of HMF was 23.7% for activated charcoal. Spiking of samples with known amounts of patulin and fumaric acid revealed respective recovery rates of 96.4% and 95.9%.     

EFFECT OF APPLE DECAY PROPORTION ON THE PATULIN, FUMARIC ACID, HMF AND OTHER APPLE JUICE PROPERTIES

Starking apples, classified by the decay proportion on the fruit surface as sound, 30, 60 or 100% decayed were used in the production of apple juice. Then patulin, fumaric acid, HMF, pH, brix and Hunter L, a and b values of apple juice samples were determined. Patulin and fumaric acid analysis were done with HPLC. The patulin concentration in juice samples produced with Starking apples that are sound, 30, 60 and 100% decayed ranged between 0.0–15.9 μg/kg, 47.1–500.3 μg/kg, 156.4–2257.5 μg/kg, 54.9–2508.6 μg/kg, respectively. The fumaric acid concentration in the same juice samples ranged between 0.00–0.20 mg/kg, 0.23–0.69 mg/kg, 0.41–2.08 mg/kg and 1.40–4.14 mg/kg. In general, the color values (L, a, b) of the samples produced from 100% decayed apples measured by reflectance with a Hunter colorimeter were low when compared with the others.     

Saturable Bragg reflector-based continuous-wave mode locking of Yb:KGd(WO 4) 2 laser

We demonstrate the saturable Bragg reflector (SBR)-based stable self-starting continuous-wave mode locking of a Yb:KGd(WO₄)₂ laser. With a double quantum well SBR structure the shortest pulses observed had durations of 169 fs, average powers of 18 mW and an oscillating wavelength centred on 1028 nm.     

Effect of shooting period, region of growth and processing method on the Fe and Mn content of tea determined by X-ray fluorescence

X-ray fluorescence (XRF) is an effective technique for qualitative and quantitative analysis of minerals in various agricultural products. Simplicity, high throughput and the possibility of automation make it useful for screening large numbers of samples. Samples of 138 fresh green, black tea and residue of this black tea after brewing were obtained from the Eastern Black Sea region of Turkey and analysed for Fe and Mn content using XRF. Such work appears not to have been reported so far.     

Corrosion of Au–Pd–In alloy in simulated physiological solutions

The corrosion of Au–Pd–In alloy, which is of great importance in dentistry, has been studied using an electrochemical quartz crystal microbalance (EQCM) in simulated physiological solutions. The alloy was deposited on quartz substrates by means of magnetron sputtering (MS). Analysis performed using X-ray photoelectron spectroscopy showed that the chemical composition of the sputtered deposit was similar to that of the MS target made of conventional casting alloy. Investigations by X-ray diffraction indicated a crystalline structure of the MS alloy. The electrochemical and corrosion behaviour of the Au–Pd–In alloy was studied in three simulated physiological solutions: 0.9 M NaCl, 0.1 M NaCl + 0.1 M lactic acid and artificial saliva. Determination of break down potential was complicated by the anodic gold dissolution due to formation of a chloride complex. The onset of anodic currents, therefore, indicated not the potential at which the passive layer starts to be destroyed, but the exceeding of the Au/AuCl₄ ^– equilibrium potential, which does not directly reflect corrosion resistance. The EQCM measurements under open circuit conditions indicated corrosion as an increase in mass, caused by the accumulation of corrosion products on the alloy surface. The increase in mass in acidic solution (pH 2.2) was similar to that in neutral solution (pH 6.5), which implies dissolution of corrosion products to be insignificant.     

EFFECT OF ACTIVATED CHARCOAL ON WATER-SOLUBLE VITAMIN CONTENT OF APPLE JUICE

The effect of activated charcoals (0, 0.5, 1.0, 2.0 and 3.0 g/L of powdered and granular activated charcoals) on the content of several water-soluble vitamins in apple juice was studied. Apple juice samples with activated carbon added were mixed for 0 (control), 5, 10, 20, and 30 min, respectively. The content of water-soluble vitamins was analyzed by HPLC. Considerable reduction in ascorbic acid (Vit C), niacin, pyridoxine (Vitamin B₆), thiamine (Vitamin B₁) and biotin concentrations was found while there was a dramatic improvement in the color and clearness of apple juice. The highest decrement in water-soluble vitamins was obtained at 3.0 g/L powdered activated charcoal. Statistical analysis of the data showed highly significant differences (P |< 0.05, P < 0.01) in the water soluble vitamins, color and clearness of the apple juice samples between the dosages of activated charcoals but no significant differences induced by the mixing periods.