It's probably the most scientific manuscript about leftovers

ring  dine out or cook at home,
we often have leftovers and leftovers.
Throw it,
feel pity,
but leave to the next meal to eat,
and worried that it will produce harmful substances such as nitrite,
and even worried about eating carcinogenic! So,
what is the nitrite produced in the leftovers? What exactly is better for health? What can be saved and which should not be kept? Listen to what the authoritative nutrition expert says! The associate professor of experts of China Agricultural University College of food science and Nutritional Engineering China Agricultural University he Jiguo College of food science and Nutritional Engineering Professor Shen Qun of China Agricultural University College of food science and Nutritional Engineering Director of the nutrition department associate professor Fan Zhihong Beijing Chaoyang Hospital dietitian Song Xin Dalian City Center Hospital Wang Xingguo lefto