Search

Furan, which has been identified as a carcinogenic risk for humans, can be induced in different foods by UV-C light. In this study, we hypothesized that furan was produced by a UV light-induced free radical mechanism and antioxidants could suppress its formation. Our results demonstrated that, by adding antioxidants, such as butylated hydroxyl toluene, ascorbic acid or gallic acid, to simulated juice or apple cider during UV-C treatment, amounts of furan were significantly reduced. For example, the concentration of furan produced in apple cider by UV-C at 9.0 J/cm2 was 636 ppb but was less than 20 ppb with 0.25 ppm butylated hydroxyl toluene present, less than 3 ppb with 0.5% (w/v) ascorbic acid, and less than 1.0 ppb with 0.5% (w/v) gallic acid. These findings confirmed that antioxidants can be used as a safe and simple mitigation measure to control furan production in fruit drinks exposed to UV-light.

A headspace solid phase microextraction (HS-SPME) procedure followed by gas chromatography-flame ionisation detector (GC-FID) analysis was developed and validated for the simultaneous analysis of furan, 2-methylfuran and 2-pentylfuran from juice samples. Extraction at 32 °C for 20 min with stirring at 600 rpm and NaCl concentration 15% (W/V) was the optimal HS-SPME condition for all the three compounds by using a carboxen/polydimethylsiloxane fused silica fibre (75 μm). The extracted compounds were base line separated on a SPB-1 GC column within 12 min. The relative standard deviations of all analytes were less than 6.7%. The recovery rates were between 90.2% and 110.1%. The limits of detection and limits of quantification were 0.056-0.23 ng/mL and 0.14-0.76 ng/mL, respectively. The results showed that the developed method was sensitive, precise, accurate and robust for the determination of furan, 2-methylfuran and 2-pentylfuran in complex matrices without interferences from other components.

There are mainly two protocols in isoflavone analysis, one that involves hydrolysis prior to HPLC analysis and the other direct HPLC analysis. In this study, three different hydrolysis methods were systematically re-evaluated, and compared with direct HPLC analysis. Acidic hydrolysis (1.2–3 M HCl in ethanol at 80 °C) showed a maximum conversion of ca. 92% from glucosides to aglycones in 2 h; however, longer reaction caused degradation of genistein. Alkaline hydrolysis using 2 M NaOH converted acetylglucosides and malonylglucosides to their respective glucosides within 10 min. Glucuronidase from H. pomatia effectively converted isoflavone glucosides and acetylglucosides to aglycones. Quantification of the total isoflavones in various soy food products showed no significant difference among direct injection and the three hydrolysis methods ( P

Soybean seeds with three different levels (low, intermediate and high) of isoflavones were processed to soy flour and soy protein isolates (SPIs) and developed into functional soy breads. The effect of factors involved in all steps of the process was investigated by tracking the composition and concentration of native forms of isoflavones. The total isoflavone contents were 8033.3, 10570.1 and 15169.0 nmol/g DM (dry matter) in the three soybeans; 13201.5, 20034.4 and 26014.3 nmol/g DM in defatted soy flours; 9113.2, 13274.6 and 17918.3 nmol/g DM in the SPI; 2782.7, 4081.4 and 5590.3 nmol/g DM in soy breads, respectively. The bread making processes did not affect the total isoflavone content, but changed glucosides/acetylglucosides to aglycones. Malonylglucosides were stable prior to baking but degraded to acetylglucosides and further to glucosides during baking. Our results provide critical information for the production of functional soy breads that contain varying amounts of soy isoflavones.