How Are Russian Olive Foods Developed and Utilized? A Full Explanation of Pathways and Value
Russian olive (Elaeagnus angustifolia L.), also known as Guixiang willow, silver willow, or Qilixiang, belongs to the Elaeagnaceae family, genus Elaeagnus. It is an evergreen shrub. Russian olive is light-demanding, cold-tolerant, highly resistant to wind-blown sand and saline-alkali conditions, grows fast, has wide uses, and holds high economic value. Russian olive is distributed in Shaanxi, Gansu, Inner Mongolia, Ningxia, **, Qinghai and other places; in ** it is found in the Taklamakan Desert and along the banks of various rivers, and it is also distributed in Yili, Toksun and other places in northern **. Russian olive is a "treasure tree" of desert saline-alkali land; its edible value and medicinal value are both very high, and it has great potential for development into green foods.
1. Main Components and Health Functions of Russian Olive Fruit, Flowers, and Pits
Russian olive fruit, flowers, branches, leaves, bark, etc. can all be used as medicine; they mainly treat burns, chronic bronchitis, closed fractures, indigestion, neurasthenia and other conditions. Russian olive also has the functions of strengthening the spleen and stomach, calming the nerves, sedation, and stopping diarrhea and astringing the intestines. Russian olive is rich in nutrients and is an ideal health food.
1.1 Russian Olive Fruit
Russian olive fruit ripens from late September to early October, and the ripe fruit is mostly oval or elliptical. The fruit pulp powder contains 7.94% crude protein, 1.34% crude fat, and 53.41% sugar, and can be used for processing various non-staple foods and can replace grain. The protein contains 17 amino acids including glutamic acid and threonine, and in particular the 8 essential to the human body are abundant; the main sugars in the pulp are fructose and glucose; the pulp also contains water, free acids, pectin, vitamin C, tannins, etc. In addition, it is also rich in various trace elements, such as phosphorus, calcium, iron, zinc, manganese, nicotinic acid, thiamine, riboflavin, carotene, etc., and especially the zinc content is relatively high, which is greatly beneficial to human intellectual development. According to the records of the former Soviet Union's medicinal plant records, Russian olive fruit contains concentrated substances of tannins and gums. As an astringent it is used for colitis, and taking it in large amounts can improve the function and state of the digestive organs. This tannin can be used as a gargle for various inflammations of the oral cavity, and experiments have shown that it has antibacterial and anti-inflammatory effects.
1.1 Russian Olive Flowers
Russian olive flowers are silvery white, pendulous, funnel-shaped, 5-7 mm long. According to "Chinese Economic Plant Records," fresh flowers contain 0.2-0.4% aromatic oil, which can be refined into essence and spices. The main components of Russian olive flowers are trinaphthol, leucoanthocyanins, fats and a small amount of volatile oil. Russian olive flowers contain a certain amount of flavonoids, and flavonoids have good application value in both medicine and the food industry. Flavonoids have effects such as treating heart disease, lowering serum cholesterol, inhibiting platelet aggregation, anti-ulcer, anti-tumor, anti-inflammatory, anti-allergic, anti-aging, anti-radiation, anti-viral, and enhancing immunity, and scavenging hydroxyl free radicals. Flavonoids can also be used in the food industry as antioxidants, pigments and sweeteners.
1.3 Russian Olive Fruit Pits
The fruit pits contain soluble sugar, protein, crude fat, crude fiber and ash, etc. The protein content is higher than that of corn and sorghum, and the fat content is higher than that of sorghum. About 45% of the fat in the fruit pits is unsaturated fat, making it a health product with very high nutritional value. Besides being able to extract high-grade Russian olive oil, the fruit pits can also be processed into exquisite handicrafts.
2. Current Status of Research and Development of Russian Olive Foods
Russian olive series foods are made by deep-processing nutrient-rich Russian olive using high-tech methods, supplemented with other natural foods, into foods that are diverse in variety, rich in nutrition, convenient and ready to eat, easy to store and transport, and suitable for all ages. Russian olive series foods include: Russian olive sugar, Russian olive vinegar, Russian olive wine, multi-flavor Russian olive, Russian olive beverages, Russian olive pastries, Russian olive nutritional liquid, Russian olive jam, Russian olive flower liqueur, Russian olive flower tea and other foods, and can also be made into food additives such as Russian olive starch alkyl polyglycoside (APG) and flavonoids.
2.1 Development of Russian Olive Fruit Pulp Foods
(1) Sugar making. The original method was to add water to Russian olive flour and boil it, then filter and concentrate it into a sugar paste. Sugar can also be made by a method combining hydrolysis, extraction and compression.
Process flow: fruit harvesting -> fruit selection -> boiling and softening -> filtration -> concentration -> sterilization -> sugar output
(2) Russian olive fermented foods. Brewing liquor is done by mixing Russian olive flour with grain chaff, etc., fermenting, and then distilling to obtain baijiu. Brewing vinegar is done by mixing Russian olive flour with a certain amount of highland barley or barley flour, fermenting, filtering, and obtaining vinegar.
(3) Producing beverages. Three types of products can be made: Russian olive beverage, Russian olive juice and Russian olive concentrated juice. Through steps such as fruit harvesting, fruit selection, boiling and softening, pulping, extraction, juice-pulp separation, and juice sedimentation removal to obtain a clear liquid, Russian olive clear liquid is obtained. Russian olive clear liquid can be formulated into a beverage, sterilized, and packaged to make Russian olive soda. After Russian olive clear liquid is blended with juice, sterilized, and packaged, Russian olive juice is made. After the Russian olive clear liquid is concentrated, sterilized, and packaged, the finished Russian olive concentrated juice is made. In juice sedimentation removal, natural clarification, heat clarification and enzymatic clarification can be used. Adding active composite enzyme preparations and protein composite preparations gives the best clarification effect.
(4) Making Russian olive pastries. Through fruit harvesting, fruit selection, boiling and softening, pulping, extraction, and juice-pulp separation, the fruit pulp is formulated with nutritional ingredients such as red bean paste, flour and white sugar to make Russian olive snacks. Russian olive pastries have a rich sweet-and-sour Russian olive flavor.
(5) Russian olive jam. Through fruit harvesting, fruit selection, boiling and softening, pulping, extraction, and juice-pulp separation, the fruit pulp is formulated into jam, cooked, and packaged to make the finished Russian olive jam. Russian olive jam easily loses water when stored for a long time, so during the process of formulating it into jam a certain amount of composite gelling agent (the main component is pectin) must be added, and attention must be paid to the sugar-acid ratio.
(6) Russian olive nutritional liquid. It is made by combining rock sugar, American ginseng, longan, coix seed, bupleurum, kudzu root, scutellaria, fragrant rice sprout, Russian olive, rice wine (40 degrees) and allicin in a certain proportion to prepare Russian olive nutritional liquid. It has the effect of tonifying qi and strengthening the body, and also has the function of detoxifying and beautifying, with very obvious health effects.
(7) Preparation of Russian olive starch alkyl polyglycoside (APG). Alkyl polyglycoside, also known as lauryl glucoside (Lauryl Glucosicle), can serve as a surfactant, and controlling starch viscosity is important in food processing. Using a phytic acid and p-toluenesulfonic acid binary system as catalyst, and Russian olive and fatty alcohol as raw materials, an alkyl polyglycoside surfactant was synthesized by the transglycosylation method.
2.2 Development of Russian Olive Flower Foods
(1) Russian olive honey: it can tonify the spleen and benefit the stomach, tonify the middle and benefit qi, and nourish the blood and calm the nerves. If infused with goji berries to tonify the kidney, it tonifies both spleen and kidney and can further improve health, and it is more suitable for people with qi deficiency and aversion to cold, stomach duct pain of the deficiency-cold type, spleen-stomach deficiency-cold, and abdominal distension and constipation. Russian olive blooms from May to June each year, and the flowering period is about 20-30 days. The nectar is a top-grade honey, light in color and high in concentration. For each hectare of 8-10-year-old Russian olive grove, 30 bee boxes can be kept during the annual flowering period, producing 450 kg of honey.
(2) Making flower liqueur. Using fresh Russian olive flowers as raw material and pickling them with light-aroma Daqu, Russian olive flower liqueur is made through distillation, filtration and aging.
(3) Russian olive flower tea: Russian olive flower tea is prepared using roasted green tea and Russian olive flowers as raw materials. It mainly includes: drying and cooling the original tea base, alternately stacking and spreading the raw fresh flowers, fully and evenly mixing the just-opening fresh flowers and the prepared tea base in a certain proportion, stacking the mixture for scenting, aerating the flowers to dissipate heat after scenting for a certain time, and then gathering the pile to continue scenting, etc. The Russian olive flower tea scented by this method not only retains the original tea aroma of the tea leaves, but also absorbs the fragrance and sweetness of Russian olive flowers, and is a new type of scented tea with local characteristics.
(4) Extracting Russian olive flower flavonoids. Shi Yuping et al. studied the optimal extraction conditions for the active ingredient flavonoids in Russian olive flowers. The results showed that the optimal conditions for extracting flavonoids from Russian olive flowers using edible alcohol as the extraction agent were: 95% edible alcohol, constant-temperature extraction at 76°C for 45 min, and the yield of flavonoids from dried fresh Russian olive flowers was 0.68%.
2.3 Development and Research of Fruit Pit Foods
Russian olive fruit pits can not only be made into exquisite decorative items, but can also be pressed to produce high-grade nutritional health oil. The components of Russian olive pit oil are mainly unsaturated fatty acids; this oil can lower blood lipids and cholesterol and is very beneficial to health. Russian olive seeds are crushed, cold-soaked and extracted several times with petroleum ether, the extracts are combined, the solvent is recovered on a rotary thin-film evaporator, and dried with anhydrous sodium sulfate to obtain pale yellow Russian olive oil, with a yield of 2.3%. The physicochemical constants of Russian olive oil are: refractive index 1.4776, specific gravity 0.9419, iodine value 159.32, saponification value 201.77. This indicates that Russian olive oil can serve as a nutritional health oil, is an ideal natural food and medicine, and has good prospects for development and utilization.
3. Development Prospects of Russian Olive Foods
Russian olive is widely planted in ** as a windbreak forest, and natural resources are extremely rich. Russian olive is a tree species with very high economic value, characterized by strong stress resistance, easy cultivation and propagation, fast growth, and high ecological benefits. Russian olive trees are drought-tolerant and salt-alkali-tolerant, and mostly grow in gobi, desert and semi-desert zones, where there is less pollution, so Russian olive is an ideal green agricultural product. In the northwest region, Russian olive variety resources are very rich, and all parts of the Russian olive - stems, leaves, flowers and fruits - have utilization value. Russian olive fruit is also easy to store, so raw materials for food processing will not be in short supply, and the comprehensive utilization value is high, so Russian olive has great advantages in food processing.
However, at present there are still the following three problems in the development and utilization of Russian olive foods: First, there is a lack of deep-processing technology for Russian olive foods, such as headache after drinking Russian olive wine, Russian olive vinegar and beverages being prone to spoilage, and some Russian olive fruits being rather astringent. These unresolved problems in food processing have all affected the marketing of Russian olive foods. Second, it is necessary to select Russian olive varieties suitable for processing. Third, there is still insufficient awareness of developing Russian olive production; people only focus on the role of Russian olive trees in windbreak and sand fixation, and have not noticed the huge economic benefits brought by deep processing of Russian olive.
The northwest region is the main production area of Russian olive in China, with uniquely favorable natural conditions suitable for Russian olive growth. At present, the Russian olive processing industry has two development trends: on one hand, accelerating research on the characteristics of Russian olive to select special varieties suitable for processing. On the other hand, accelerating research on deep processing of Russian olive foods. We should select Russian olive varieties suitable for processing, plant them in large quantities, and provide advanced Russian olive processing technology, so that the Russian olive processing industry develops rapidly and achieves the combination of ecological benefits, social benefits and economic benefits.