Davaritouchaee Maryam, Mosleh Imann, Dadmohammadi Younas, Abbaspourrad Alireza
Department of Food Science, College of Agriculture & Life Sciences, Cornell University, Stocking Hall, Ithaca, New York, NY 14853, USA.
Polymers (Basel). 2023 Jan 30;15(3):697. doi: 10.3390/polym15030697.
Orange peels are an abundant food waste stream that can be converted into useful products, such as polyhydroxyalkanoates (PHAs). Limonene, however, is a key barrier to building a successful biopolymer synthesis from orange peels as it inhibits microbial growth. We designed a one-pot oxidation system that releases the sugars from orange peels while eliminating limonene through superoxide (O) generated from potassium superoxide (KO). The optimum conditions were found to be treatment with 0.05 M KO for 1 h, where 55% of the sugars present in orange peels were released and recovered. The orange peel sugars were then used, directly, as a carbon source for polyhydroxybutyrate (PHB) production by engineered . Cell growth was improved in the presence of the orange peel liquor with 3 /% exhibiting 90-100% cell viability. The bacterial production of PHB using orange peel liquor led to 1.7-3.0 g/L cell dry weight and 136-393 mg (8-13 /%) ultra-high molecular weight PHB content ( of ~1900 kDa) during a 24 to 96 h fermentation period. The comprehensive thermal characterization of the isolated PHBs revealed polymeric properties similar to PHBs resulting from pure glucose or fructose. Our one-pot oxidation process for liberating sugars and eliminating inhibitory compounds is an efficient and easy method to release sugars from orange peels and eliminate limonene, or residual limonene post limonene extraction, and shows great promise for extracting sugars from other complex biomass materials.
橙皮是一种丰富的食物废物流，可以转化为有用的产品，如聚羟基脂肪酸酯（PHA）。然而，柠檬烯是利用橙皮成功合成生物聚合物的关键障碍，因为它会抑制微生物生长。我们设计了一种一锅法氧化系统，该系统能从橙皮中释放出糖分，同时通过超氧化钾（KO₂）产生的超氧阴离子（O₂⁻）消除柠檬烯。发现最佳条件是用0.05 M KO₂处理1小时，此时橙皮中55%的糖分被释放并回收。然后，橙皮糖直接用作工程菌生产聚羟基丁酸酯（PHB）的碳源。在橙皮液存在的情况下，细胞生长得到改善，3%的接种量显示出90 - 100%的细胞活力。利用橙皮液进行细菌生产PHB，在24至96小时的发酵期内，细胞干重达到1.7 - 3.0 g/L，超高分子量PHB含量为136 - 393 mg（8 - 13%）（分子量约为1900 kDa）。对分离出的PHB进行的综合热表征显示，其聚合物性质与由纯葡萄糖或果糖产生的PHB相似。我们用于释放糖分和消除抑制性化合物的一锅法氧化工艺是一种从橙皮中释放糖分并消除柠檬烯或柠檬烯提取后残留柠檬烯的高效简便方法，并且在从其他复杂生物质材料中提取糖分方面显示出巨大潜力。
