Harvesting and Processing Techniques for Pollution-Free Honeysuckle

Honeysuckle is a perennial, semi-evergreen woody vine of the Caprifoliaceae family, Lonicera genus, also known as Erhua, Shuanghua, etc., and is a precious traditional Chinese medicinal herb. Because of its remarkable heat-clearing and detoxifying effects, as well as its role in lowering blood pressure and delaying aging, it is hailed as a traditional Chinese medicine antibiotic and an elixir of immortality. The production and development of honeysuckle have increasingly attracted people's attention. The harvesting and processing of honeysuckle are the last two "procedures" in the production chain, and also the final guarantee of "high yield, high efficiency, quality, and safety." In recent years, the Fengqiu County Agriculture Bureau of Henan Province, in order to improve the comprehensive benefits of honeysuckle, has continuously improved and innovated traditional production methods and techniques, creating the optimal harvesting method for honeysuckle and the "four-stage variable-temperature drying technology for drying rooms," which has been affirmed by national authoritative departments and plays a major role in production. The technology is described below:

1. Harvesting

For improved varieties of honeysuckle such as Fengqiu Damaohua and Jizhuahua, those planted in spring can bear flowers in the same year, while those planted in autumn and winter bear flowers the following year. Therefore, once honeysuckle is planted, the issue of flower bud harvesting and processing must be considered, and containers for harvesting flower buds must be prepared and drying rooms for flower bud processing must be built.

1. Flower bud development pattern of honeysuckle

Fengqiu Damaohua blooms 4 times per year in North China. The first flush begins to sprout buds in mid-April, gradually increasing thereafter, and by mid-May the flower buds mature and begin to bloom. The first flush ends at the end of May, after which each flush occurs about every 30 d. The fourth flush is not concentrated and may continue blooming until early October.

A single honeysuckle flower takes about 13-20 d from bud emergence to opening, longer in spring, while in summer and autumn with higher temperatures, flower buds develop faster and the development time is shorter. When the flower bud grows to 1/2 of its expected length, development accelerates, and the bud color begins to change from green to white. If not harvested in time, it will open.

2. Harvesting timing

From bud emergence to opening and withering, honeysuckle can be divided into the following stages: rice-bud stage, young-bud stage, green-bud stage, early white-bud stage (white on top, green below), white-bud stage (all white top and bottom), silver-flower stage (just opening), golden-flower stage (1 or 2 d after opening until just before withering), and withering stage. Harvesting before or during the green-bud stage yields less dry matter and lower medicinal value, affecting both yield and quality; harvesting after the silver-flower stage gives high dry matter content but decreased medicinal components, resulting in high yield but poor quality. Harvesting at the early white-bud stage and white-bud stage gives more dry matter and high medicinal components, yield, and quality, but harvesting at the white-bud stage easily misses the optimal timing. Therefore, the best harvesting period is the early white-bud stage, known by growers as the "two-white needle stage."

3. Harvesting method

The best time to harvest honeysuckle is early morning and before noon, when harvested flower buds are less likely to open and have sufficient nutrients, strong fragrance, and good color. Harvesting in the afternoon should be completed before sunset, because the opening of honeysuckle is governed by light, and after sunset mature flower buds will open, affecting quality. When harvesting, only mature flower buds and nearly mature flower buds should be picked, without young buds or leaves. After picking, place them in baskets woven from strips or bamboo. When gathering them together, do not pile them into large heaps; spread them out instead, and do not leave them for too long, no more than 4 h.

2. Processing

The primary processing of honeysuckle is to turn freshly collected flower buds into dried flower buds through certain methods. The main methods include air-drying, sun-drying, and oven-drying. Air-drying and sun-drying are gradually being phased out because they are unsuitable for large-scale processing and yield poor, unstable quality. The main processing method used in production is open-flame drying. This method is unaffected by weather and produces dried flower buds of good quality, and is widely adopted by growers. However, the disadvantage of "open-flame drying" is serious contamination by harmful substances such as sulfur dioxide. In recent years, agricultural technicians and herb growers in Fengqiu County, Henan Province, have jointly created the "four-stage variable-temperature drying technology for drying rooms," which reduces contamination by harmful substances such as sulfur dioxide and achieves pollution-free processing. The specific method is as follows:

1. Construction of drying room and drying racks

First, the scale of the drying room should be determined according to the size of the planting area. Generally, every 667 sq m of honeysuckle requires about 4-5 sq m of drying room. The drying room is generally a single-story house, and there are 2 construction methods: (1) Single-row rack type: the length of the drying room depends on the honeysuckle area, the width is 2-2.2 m, the height is 2-2.5 m, with one door and one window, and 2 exhaust vents at the top. The drying rack is built along one side of the long wall of the room, with a width of 0.8 m and a height of 2-2.5 m. The lowest layer is at a height of 0.8-1 m, and every 15-20 cm upward is 1 layer, for a total of 6-10 layers; (2) Double-row rack type: the length of the drying room depends on the honeysuckle area, the width is 2.5-3.2 m, the height is 2-2.5 m, with one door and one window or two windows, and 2-3 exhaust vents at the top of the room or near the eaves. Regardless of whether it is single-row or double-row, the inner walls of the drying room are required to be smooth and clean and airtight.