Suhem Kitiya, Matan Narumol, Matan Nirundorn, Danworaphong Sorasak, Aewsiri Tanong
Food Technology, School of Agricultural Technology, Walailak University, Nakhon Si Thammarat 80160, Thailand.
Food Technology, School of Agricultural Technology, Walailak University, Nakhon Si Thammarat 80160, Thailand; Green Innovation in Physics for Agro-Industry Research Center of Excellence, Walailak University, Nakhon Si Thammarat 80160, Thailand.
Int J Food Microbiol. 2015 Dec 23;215:157-60. doi: 10.1016/j.ijfoodmicro.2015.09.008. Epub 2015 Sep 14.
The aim of this study was to improve the antifungal activity of the volatile Litsea cubeba essential oil and its main components (citral and limonene) on brown rice snack bars by applying He-Ne laser treatment. Different volumes (50-200 μL) of L. cubeba, citral or limonene were absorbed into a filter paper and placed inside an oven (18 L). Ten brown rice snack bars (2 cm wide × 4 cm long × 0.5 cm deep) were put in an oven and heated at 180 °C for 20 min. The shelf-life of the treated snack bars at 30 °C was assessed and sensory testing was carried out to investigate their consumer acceptability. A count of total phenolic content (TPC) and Fourier transform infrared spectroscopy (FTIR) on the properties of essential oil, citral, and limonene before and after the laser treatment was studied for possible modes of action. It was found that the laser treatment improved the antifungal activity of the examined volatile L. cubeba and citral with Aspergillus flavus inhibition by 80% in comparison with those of the control not treated with the laser. L. cubeba vapor at 100 μL with the laser treatment was found to completely inhibit the growth of natural molds on the snack bars for at least 25 days; however, without essential oil vapor and laser treatment, naturally contaminating mold was observed in 3 days. Results from the sensory tests showed that the panelists were unable to detect flavor and aroma differences between essential oil treatment and the control. Laser treatment caused an increase in TPC of citral oil whereas the TPC in limonene showed a decrease after the laser treatment. These situations could result from the changing peak of the aliphatic hydrocarbons that was revealed by the FTIR spectra.
本研究的目的是通过应用氦氖激光处理来提高挥发性山苍子精油及其主要成分（柠檬醛和柠檬烯）对糙米零食棒的抗真菌活性。将不同体积（50 - 200 μL）的山苍子、柠檬醛或柠檬烯吸收到滤纸上，放置在一个烤箱（18升）内。将十根糙米零食棒（宽2厘米×长4厘米×深0.5厘米）放入烤箱中，在180℃下加热20分钟。评估经处理的零食棒在30℃下的保质期，并进行感官测试以调查其消费者接受度。研究了激光处理前后精油、柠檬醛和柠檬烯的总酚含量（TPC）计数以及傅里叶变换红外光谱（FTIR），以探究可能的作用模式。结果发现，与未用激光处理的对照相比，激光处理提高了所检测的挥发性山苍子和柠檬醛对黄曲霉的抑制抗真菌活性，抑制率达80%。发现经激光处理的100 μL山苍子蒸汽能完全抑制零食棒上天然霉菌的生长至少25天；然而，没有精油蒸汽和激光处理时，3天内就观察到了自然污染的霉菌。感官测试结果表明，小组成员无法检测出精油处理组和对照组之间的风味和香气差异。激光处理使柠檬醛油的TPC增加，而激光处理后柠檬烯中的TPC则有所下降。这些情况可能是由FTIR光谱显示的脂肪烃峰变化导致的。
