As for zongzi, the earliest written record was in the book "General Meaning of Customs" written by Yingshao, the Taishou of Mount Tai, which mentioned: "The custom wraps millet in leaves and cooks it in thick ash juice, from May 5th to summer solstice, in order to get a thorough taste."
In this period, the sweet and salty characteristics of zongzi are not very prominent. The grey juice mentioned above refers to the water leached from plant ash. Zongzi cooked with "pure grey juice" is neither sweet nor salty.
Zongzi with grey juice is not unique to the Eastern Han Dynasty. When rice dumplings were mentioned in the northern Wei farming book Qi Yao Min Shu, they were also cooked with "millet jujube ash juice".
Perhaps at that time, when zongzi was used for sacrificial activities, it was more ceremonial than edible, so that it didn't improve its taste for hundreds of years.
Zongzi must be delicious if it can appear on such an occasion. Unfortunately, the records of the Tang people always pay attention to the shape of zongzi, such as dumpling zongzi, cone zongzi, ling zongzi, tube zongzi, qizi zongzi, weighing zongzi ... and never record whether their taste is salty or sweet.
Until the Song Dynasty, the market culture flourished, and the varieties of zongzi were much more colorful than the previous generation. Lin 'an, the capital of the Southern Song Dynasty, even "used various methods to make zongzi into pavilions and carts".
Records about the taste of zongzi finally appeared. These records all refer to sweet zongzi.
For example, in the works of Zhang Lei in the Northern Song Dynasty, it was mentioned: "The water mass is wrapped in crystal sugar and has transparent horns and pine." Zongzi is not only sweet, but also can be chilled. The "molasses dumplings" recorded in the careful Biography of the Old Wulin in the Southern Song Dynasty also flaunted its sweetness from its name.
The technology of sweet zongzi is mature, while salty zongzi, at least from the written records, can not find evidence of its existence in the Song Dynasty. In other words, in the Southern Song Dynasty when Yang Guo and Cheng Ying lived, there was no question of whether zongzi was salty or sweet. As long as you want to eat zongzi, it is sweet zongzi.
When the salty zongzi came out, it was already in the middle of the Ming Dynasty. Huating (now Songjiang, Shanghai) and his son Song wrote a diet book, Bamboo Rain Mountain Miscellaneous House, in which Zongzi was written. Among the sweet fillings such as "honey bean paste", "fat jujube" and "peeled walnut", there is also a kind of "pork paste", that is, zongzi stuffed with pork sauce, which may be salty.
As for Jin Yong's ham zongzi, it was not until the middle of Qing Dynasty that it was recorded in Yuan Mei's Suiyuan Food List, which originated from Yangzhou Hongfu: a large piece of ham was put in glutinous rice with full grains, wrapped in big leaves and stewed for a day and a night, "the food was greasy and moist, and the meat was rice-like".
This kind of food is no different from today's salty zongzi except that it is steamed for too long.