Detailed Explanation of Key Processing Techniques for Lanzhou Lily

Lanzhou lily is a perennial herbaceous plant of the Liliaceae family, with a long history of cultivation in Lanzhou. Because its underground stem consists of dozens of scale leaves embracing each other, with the characteristic of a hundred pieces combining into one, it implies the meanings of "everything going as wished" and "a harmonious union lasting a hundred years," and it also has medicinal effects such as strengthening the stomach, tonifying deficiency, resolving phlegm, and nourishing yin, so it is deeply loved by consumers. Lanzhou lily is drought-tolerant and suitable for planting in high-cold mountainous areas above 2000 m in altitude. In producing areas with a cool climate, large temperature differences between day and night, and few pests and diseases, the lily accumulates more dry matter, and its color is pure white, its flesh is thick, plump and delicate, its taste is delicious, and it is rich in nutrients.

1. Harvest period

The harvest period of Lanzhou lily has a relatively large impact on the processing quality of the lily. Generally, from November 15 of each year to March 15 of the following year, after digging it is simply sorted and put into baskets, transported to the market or refrigerated, and gradually marketed. Lilies dug prematurely before the digging period generally have poor taste and incomplete nutritional components, and are called "green-stem" lilies by local people. Because the lily@#@136@#@time is short, processing treatment should be used to extend the sales time, expand the sales area, and achieve year-round supply. At present, common lily processed products mainly include three types: vacuum-packed fresh lily, baked Lanzhou dried lily, and lily powder.

2. Processing technology for vacuum-packed fresh lily

Fresh lily processed with vacuum packaging technology has better color, aroma, taste, and shape. When stored away from light in a cold storage at 0°C to 4°C, the freshness period can reach 60 days, making it convenient for long-distance trafficking and storage for sale. Its main production process is as follows:

(1) Lily selection According to the "Lanzhou Lily Quality Grading Standard" issued and implemented by the Gansu Provincial Bureau of Quality and Technical Supervision under DB62/412-95, fresh lily is divided into special grade, first grade, second grade, and third grade according to the transverse diameter, number of separated cloves, and uniformity of the product, as shown in Table 1.

Table 1 Quality grading indicators of Lanzhou lily

Item Special grade First grade Second grade Third grade

Transverse diameter cm ≥9.0 ≥9.0 8.0-8.9 8.0-8.9 7.0-7.9 6.0-6.9

Number of separated cloves 1-2 3-4 1-2 3-4 1-2 1-2

Uniformity % ≥98 ≥95 ≥95 ≥95

(2) Removing soil Use a bristle brush to remove soil and peel off the outer skin. After treatment, the lily should be fresh and white, with no rotten spots, no damaged spots, no insect spots, and no rust spots. The fleshy fibrous root part must not carry soil, and the fibrous root length must not exceed 1 cm.

(3) Weighing and subpackaging Weigh fresh lily that meets the standards of each grade and subpackage it into bags.

(4) Sampling inspection Randomly take out the lily that has been subpackaged into bags, observe changes in its color, tissue morphology, and taste, remove nonconforming products, and make up the bagged weight.

(5) Packaging and storage Place the bagged lily into a vacuum packaging machine for vacuum packaging, then place it in a cold storage at 0°C to 40°C for light-protected storage. Goods must be stacked 10 cm above the ground, and a 10 cm ventilation passage must be left between goods.

3. Processing technology for dried lily and lily powder

(1) Lily selection The raw materials for processing dried lily and lily powder are: ① lilies with a transverse diameter less than 6 cm or more than 5 heads and small scale leaves after processing vacuum-packed fresh lily; ② scale segments peeled off during the processing of vacuum-packed fresh lily; ③ finished fresh lily that needs processing.

(2) Scale separation and cleaning Separate scales piece by piece from the selected large fresh lily bulbs, keeping the scales intact. Soak the separated and graded lily scales in water to soften attached matter, then wash 1 to 2 times with clean water to remove soil, sand dust, residues, and microorganisms attached to the surface, ensuring the cleanliness and hygiene of the raw materials.

(3) Blanching treatment Put the washed lily segments into a boiling water pot by grade for blanching. The ratio of water amount to lily mass is 10:3, and the water must submerge the lily pieces. Stir slowly in the pot with a wooden board (stick) so that the lily is blanched evenly. The suitable blanching times for first-grade pieces, second-grade pieces, and third-grade pieces are 60 s, 40 s, and 10 s respectively. Properly blanched lily is rice-yellow, with transparent tissue, losing its fresh hardness, but not mushy. The sensory performance is that scraping the scale skin with a fingernail produces a powdery appearance, the scale is not crisp when tasted, and the broken section has a uniform color with no white core. Under normal circumstances, when a pot of water becomes cloudy after continuous blanching 2 to 3 times, clean water should be replaced. After scooping the blanched lily pieces out of the pot, quickly place them into cool water to cool, then pour them into bamboo trays or porcelain trays for drying in the sun, spread flat and preferably not overlapping.

(4) Drying and sulfur fumigation Drying methods include natural drying, artificial baking room drying, and mechanical drying. At present, artificial drying is mostly used, and it includes three steps: heating and raising temperature, ventilation and moisture removal, and loading and placing raw materials. Drying is generally carried out simultaneously with sulfur fumigation bleaching. The sulfur fumigation method is to choose pure sulfur powder with an arsenic content of less than 0.015% to fumigate lily pieces; the dosage is 0.2% to 0.5% of the raw material mass, or sulfur can be fumigated at 150 g/cubic meter according to the size of the baking room. The specific method is to place an iron container holding sulfur powder on the stove so that it is heated and burns. Sulfur fumigation bleaching can destroy the biological enzyme system of the lily, prevent enzymatic browning, and can kill various microbial pathogens attached to the scales, accelerate water evaporation, shorten the drying and dehydration time, and also make dried lily white in color. During sulfur fumigation, the Ministry of Health's "Hygienic Standard for the Use of Food Additives" must be strictly implemented, and the sulfur dioxide content must not be higher than 100 mg/kg.

(5) Baking room baking The key technical points of baking are properly adjusting indoor temperature and humidity. After the raw materials are sent into the baking room, close doors, windows, and ventilation facilities. After baking begins, the temperature in the baking room rises, and the temperature should preferably be controlled at 70°C to 75°C. When the indoor relative humidity exceeds 70%, ventilate for 10 min to 15 min; when the relative humidity in the baking room drops to about 55%, close the ventilation facilities, and afterward ventilate and remove moisture 4 to 5 times based on the hygrometer. When using the hot-air drying method, first pass in steam and then turn on the fan. When the temperature in the baking room rises to 70°C, the exhaust fan must be turned on to remove moisture, removing moisture once every 20 min to 30 min. After 2 h, appropriately extend the moisture removal time depending on the dryness or wetness of the lily. In the later stage of baking, most of the water in the scales has been lost and the surface is soft, so drying should continue until it fully meets the requirements. Properly baked finished dried lily is easy to shake in the baking tray, feels hard and crisp, does not become soft in the middle when broken, and makes a sound when the dried pieces are broken. During the entire baking process, inspect and turn frequently so that the baked lily scales are heated evenly. After baking ends, promptly spread the dried pieces out to dissipate heat, and finally pile them together and ventilate to soften, so that the dried lily pieces are evenly dry and moist, with a moisture content below 11%.

(6) Grading and packaging After the baked dried lily cools, those with excessively high moisture should be selected out and baked again. Remove old skin, lily cores, scarred pieces, and discolored scales, then grade and package.

(7) Grinding lily powder Send the baked dried lily, or the dried lily remaining after grading and packaging, into a grinder to produce lily powder.