Off-flavors generated during long-term ambient storage of pasteurized drinking yogurt from skim milk
Kazuhiro Miyaji, Yasuyuki Kuwano, Yusuke Murakami, Shunsuke Hirata, Yuriko Imayoshi, Hiroshi Maruyama, Reiko Koizumi, Hajime Inoue, Norihiro Azuma
Abstract
Few studies have examined sensory quality changes during the storage of pasteurized drinking yogurt (PDY), and the cause of off-flavor development is unclear. Off-flavors generated during 90-d ambient storage (25 °C) of PDY from reconstituted skim milk were investigated by sensory evaluation, volatile component analysis with gas chromatography-mass spectroscopy, and gas chromatography-olfactometry. Rancid off-flavor was induced by increased fatty acid concentration due to fat decomposition by heat-stable lipase. Masking of off-flavors was inhibited by degradation of diacetyl, which originally contributed to yogurt-like flavors. Maillard reaction particular to ambient storage of PDY resulted in changes in the furaneol and sotolon levels, which may be involved in enhancement of off-flavors. Finally, our findings indicated that production of 4-vinylguaiacol may be involved in off-flavor development. The results of this study will contribute to the development of PDY with a longer shelf life and superior flavor.