In vitro assessment of synthetic phenolic antioxidants for inhibition of foodborne Staphylococcus aureus,Bacillus cereus and Pseudomonas fluorescens

Minimal inhibitory concentrations (MICs) of seven synthetic phenolic compounds, five commonly used as antioxidants (TBHQ, BHA, BHT, propyl gallate and octyl gallate) and two as antimicrobials (propyl 4-hydroxybenzoate and n-heptyl 4-hydroxybenzoate) were assessed against several strains of two Gram-positive (Staphylococcus aureus and Bacillus cereus) and one Gram-negative (Pseudomonas fluorescens) bacteria, by using a standardized microdilution assay (ISO 20776-1, 2006). Octyl gallate was the most effective compound against the three genera/species of bacteria considered simultaneously (with the exception of four strains of B. cereus, which were resistant for this compound) with MIC values (≤100 μg/ml) lower than the concentrations usually used as antioxidants. TBHQ and n-heptyl 4-hydroxybenzoate were also effective in the control of S. aureus at very low concentrations (MIC of 3.1 μg/ml and 12.5 μg/ml, respectively). Propyl 4-hydroxybenzoate was the most inhibitory phenolic compound against all strains of B. cereus and both tested parabens (propyl- and heptyl-) were not effective for P. fluorescens (MIC > 1600 μg/ml). B. cereus was the bacterial genera that showed more intra-species variation, distinguishing two clearly groups of sensitivity among the strains to octyl gallate and n-heptyl 4-hydroxybenzoate (“sensitive” with mean MICs of 42.8 and 4.2 μg/ml, respectively; and “resistant” with MICs >1600 and >800 μg/ml, respectively). According to all that, octyl gallate would be an interesting phenolic compound for the food industry, not only because of its recognized antioxidant properties but also because of their effectivity as antimicrobial against S. aureus, B. cereus and P. fluorescens.     

Would repeated consumption of sports drinks with different acidulants lead to hedonic adjustment?

Repeated exposure to sports drinks with different acidulants added at equal sour concentrations led to hedonic adjustment when consumers (n = 128) evaluated a Lemon & Lime flavoured sports drink over a period of 14 days. Consumer preferences after repeated exposure could not have been predicted from the initial small sample single exposure consumer taste test. Product exposure and time on trial influenced the preferences of consumers. Products that were initially preferred became less preferred after 14 days. The findings of this study challenge the validity of sensory evaluation test strategies that rely on single exposure testing to predict long term consumer preferences.     

Simultaneous analysis of acidulants and preservatives in food samples by using capillary zone electrophoresis with indirect UV detection

Capillary zone electrophoresis with indirect UV detection was developed for the simultaneous analysis of acidulants and preservatives in food samples. When a solution of tris (hydroxymethyl) aminomethane, trimellitic acid and poly (vinyl alcohol) was used as the background electrolyte, the nine acidulants and four preservatives listed in the Japanese Food Sanitation Law were detected within 8 min. The calibration curves plotted from the peak height of each analyte were linear with a correlation coefficient of 0.99. The relative standard deviations (n = 10) of the peak height ranged from 1.2% to 4.7%. The detection limits for these species ranged from 0.6 to 5.3 mg/L at a signal-to-noise ratio of three. The method developed method was applied to the simultaneous analysis of acidulants and preservatives in a wide variety of food samples.     

超高效液相色谱同时测定含乳饮料中12种食品添加剂

目的建立超高效液相色谱法同时快速测定含乳饮料中3种甜味剂、7种防腐剂和2种酸味剂的检测方法。方法样品用水提取后,加入亚铁氢化钾和乙酸锌溶液沉淀蛋白质及其他杂质。以Waters XBridge BEHC18柱(100mm×2.1mm,i.d.1.7μm)为分离柱,甲醇-20mmol/L乙酸铵溶液为流动相梯度洗脱,流速为0.3 mL/min,采用二极管阵列检测器进行检测,检测波长为230 nm和210 nm。结果 12种目标物可以在6 min内达到较好的分离,在0.010～80μg/mL范围内呈良好的线性关系(r2≥0.9996),检出限为0.03～0.15 mg/kg,定量限0.10～0.50mg/kg,样品在3个加标水平(1、10和50mg/kg)的回收率为80.2%～99.7%,相对标准偏差为1.23%～4.70%。结论该方法操作简单,快速,适用于含乳饮料中12种食品添加剂的检测。     

Colour and flavour of potato protein preparations,depending on the antioxidants and coagulants used

The colour and profile of the aromatic compounds of potato juice (PJ) protein preparations were investigated following various process modifications. Several antioxidants (sodium bisulphate, tartaric acid, ascorbic acid), acidulants (tartaric, ascorbic and hydrochloric acids) and chelating agents (chloride, lactate and calcium hydrogen phosphate salts) used for pectin removal during the coagulation of the PJ proteins were evaluated. The combination of sodium bisulphate or ascorbic acid as antioxidants, with calcium chloride or lactate, and ascorbic acid as the protein coagulant, increased the brightness of the protein preparations. Forty-one aromatic compounds, including aldehydes, alcohols and alkanes, were identified. The total concentration of volatiles ranged 59–105 μg g⁻¹. The ascorbate variant contained the lowest n-hexanal concentration. Different treatments did not impact significantly on the 2-methyl-propanal and 2-methyl-butanal concentrations. Interestingly, 2-pentylfuran production was dramatically reduced (16.48 μg g⁻¹) in the lactic variant in comparison to 40.52 μg g⁻¹ with CaHPO₄ addition.