Efficacy of light-protective additive packaging in protecting milk freshness in a retail dairy case with LED lighting at different light intensities
乳品防光添加劑包裝在LED照明不同光照強度下牛奶保鮮功效研究
Aili Wanga,?, Catherine H. Dadmunb, Rachel M. Handc, Sean F. O'Keefea, J'’Nai B. Phillipsa,
Kemia A. Andersa, Susan E. Duncana
a Department of Food Science and Technology, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg 24061, United States
b Department of Chemistry, College of Charleston, Charleston 29424, United States
c Department of Food Science and Human Nutrition, Michigan State University, East Lansing 48824, United States
A B S T R A C T
Light emitting diodes (LED) are rapidly developing as dominant lighting systems in dairy retail cases. Bright light is typically chosen to best exhibit milk products. However, high intensity LED lighting may create high potential for detrimental oxidation and destroying milk freshness. In this study, we investigated the interaction between LED light intensity, exposure time, and packaging material on limiting milk oxidation and protecting milk freshness and vitamins. Within 4 h of LED light exposure at an intensity as low as 1068 lx, light-induced oxidation occurred on 2% milkfat milk with commercial packaging including glass and translucent high-density
polyethylene (HDPE) bottles. Higher light intensity (> 4094 lx) and longer light exposure time (> 24 h) rapidly increased the oxidation rate in milk. Polyethylene terephthalate (PET) packaging with lower oxygen permeability rate effectively reduced (P < 0.05) vitamin A degradation under low light intensity within 24 h. A combination of light-protective additive (TiO2) and oxygen barrier material (PET) successfully reduced (P < .05) the loss of dissolved oxygen and riboflavin, and decreased the formation of final oxidation products in milk, as measured by thiobarbituric reactive substances (TBARS), when exposed to high light intensity within
24 h. Lower LED light intensity in retail case was preferred by 50% of participants in a visual acceptance test; consumers are willing to consider pigmented packaging with limited visibility. Results of this study provides guidance for dairy industry in choosing appropriate LED lighting conditions and packaging to adequay display the milk products as well as minimize the degradation of milk nutrients and flavor.
發光二極管(LED)作為乳制品零售業的主要照明系統正在迅速發展。通常選擇明亮的光線來展示乳制品。然而，高強度的LED照明可能產生有害氧化和破壞牛奶新鮮度高發生率。在本研究中，我們研究了LED光強度、暴露時間和包裝材料對限制牛奶氧化和保護牛奶新鮮度和維生素的作用。在LED光照強度低至1068lx的4H內，2%的商業包裝乳脂乳(包括玻璃和半透明高密度乳脂)發生光誘導氧化。聚乙烯(HDPE)瓶。較高的光照強度(>4094lx)和較長的光照時間(>24h)迅速增加了牛奶中的氧化率。低透氧率的聚對苯二甲酸乙二醇酯(PET)包裝在24小時內有效降低了(P<0.05)*在低光強下的降解，光防護添加劑(TiO2)和阻氧材料(PET)的組合成功降低了(P<0.05)D的損失。通過硫*活性物質(TBARS)測定，當暴露在高光照強度的牛奶中時，溶解氧和核黃素，并減少牛奶中終氧化產物的形成。24小時。50%的參與者傾向于在零售情況下降低LED光強度；消費者愿意考慮能見度有限的色素包裝。本研究結果為乳品工業選擇適當的LED照明條件和包裝，充分展示乳品，并將乳品營養成分和風味的降解降到低提供了指導。
2.6.2. Electronic nose analysis
Analysis was conducted immediay after dissolved oxygen analysis using conducting polymer electronic nose (Cyranose® 320, Sensigent, Baldwin, CA) to prevent the loss of volatiles. Settings (Appendix) for the electronic nose (E-Nose) analysis were established by a preliminary study assessing the draw and purge time of the instrument (Amin, 2016). The Cyranose® 320 measurement is based on change in resistance of each chemical sensor in the 32-sensor NoseChip® when exposed to volatiles. Milk sample (5 mL) was pipetted into a lean amber glass vials (20 mL) and sealed with rubber septum and cap, and the ratio between headspace volatiles and liquid sample was 3:1 in each vial. Samples were held in water bath (65 °C) for a minimum of 10 min to allow equilibrium of volatiles to occur within the headspace. Samples were collected by piercing the airtight rubber septum with a needle and using detector of E-Nose to insert inside the vial to absorb the headspace volatiles. The process was repeated 5 times for each milk sample. E-Nose data were processed with the software of PCnose® 10.11.0.76.
溶解氧分析后立即使用導電聚合物電子鼻(Cyranose 320，Sensigent，Baldwin，CA)進行分析，以防止揮發物損失。電子鼻(e-nose)分析的設置(附錄)是通過評估儀器抽吸和吹掃時間的初步研究確定的(Amin，2016年)。Cyranose 320的測量基于32傳感器NoseChip®暴露于揮發物時每個化學傳感器的電阻變化。將牛奶樣品(5ML)用移液管移入淡黃色玻璃瓶(20ML)中，用橡膠隔墊和瓶蓋密封，每瓶頂空揮發物與液體樣品的比例為3:1。將樣品置于水浴(65°C)中至少10分鐘，以便在頂空內發生揮發物平衡。用進樣針頭刺穿密封橡膠隔墊，用電子鼻檢測器插入藥瓶內，吸入頂空揮發物，采集樣品。對每個牛奶樣品重復該過程5次。電子鼻數據使用PCNOSE®10.11.0.76軟件進行處理。
