The most important aspect of citrus juice after extraction is bitter taste which is not acceptable for consumers. This phenomenon, is known as delayed bitterness and resulted of Limonoid compounds. In compare with of the citrus fruits, amount of Limonin in Sweet lime is much higher, which is due to late expression of Limonin glucosyltransferase gene. In this study to reduce and mask the bitterness of Sweet lime juice, it was mixed with different rates of Satsuma mandarin, Valencia orange and Pine apple juice. The effects of the presence of Limonin glucosyltransferas in this citrus juice on Limonin D- ring lacton ( the precursor of Limonin) were studied. High performance liquid chromatography (C18 column, a UV–vis detector and mobile phases was acetonitrile/deionised water (32:68), flow rate 0.9 ml/min) was used to determine the amount of Limonin in mixtures. The results showed that Satsuma mandarin and Valencia orange juice had a good ability to reduce Limonin content. Addition of Pine apple juice show higher quality to mask the bitterness than the other juices, but had no effect on reducing of Limonin. All mixture juices showed less bitterness in compare with packed pasteurized grape fruit juice purchase from Iranian market. Since higher temperature induce Limonin formation in the citrus juice, pasteurization temperature was redused to 55-60°C. lower pasteurization temperature coused higher total count in the juices. in order to control microbial load, nanoparticles of Zinc oxide were added to the mixtures. Antimicrobial effects of addition of zinc oxide nanoparticles, silver oxide nano paricels and bulk form of Zinc sulfate were studied. Silver oxide nanoparticles had the higher ability against microbial load (Acidophil bacteria, total yeast and mold) than Zinc oxide nanoparticles, and bulk form of Zinc sulfate had less ability against microbial load(p 0.01). The better retention of color (greenness and lightness) was obtained when Zinc oxide nanoparticles were added in compare with bulk form of Zinc sulfate ( P 0.01). addition of both compounds show a better color than the blank. On the other hand, using of zinc oxide nanoparticles reduce microbial load of the citrus juice, could save the energy cost of production. The interesting result was observed that after keeping the Sweet lime juice (pasteurizated in 55-60°C and after adding of the zinc oxide nanoparticles) in 4°C for 4-5 weeks, the bitter taste was disappeared. Key Words: Limonin, sweet Lime Juice, delayed bitterness, Zinc oxide Nanoparticle, Silver Oxide Nanoparticle, Zince Sulfate.