Issue 19, 2012 - Research progress in industrial application of xylanase

Xylanase is an enzyme system that degrades β-1,4 xylosidic bonds in xylan molecules, which hydrolyzes xylan to xylan oligosaccharides, xylooligosaccharides, xylobiose, and small amounts of arabinose and xylose
.
Therefore, xylanase is widely used in bioenergy, food, feed, pharmaceutical, pulping, papermaking, textile and other industries, and has become a research hotspot
for many scholars at home and abroad.

First, the application of xylanase in the paper industry

Xylanase is used in the paper industry to improve bleaching effect, deink waste paper and improve fiber performance
.
The research of Gu Qiping et al.
from the College of Chemical Engineering of Nanjing Forestry University shows that the whiteness of enzymatic deinking paste is 3.
2% higher than that of control pulp, the amount of residual ink is reduced by 73.
8%, and the yield is high and the
yellowing value is low compared with chemical deinking.
Ge Peijin et al.
of Nanjing Forestry University found that when preparing wheat straw pulp by alkali method, xylanase pretreatment raw materials can better improve the efficiency of H2O2 bleaching of
wheat straw pulp.
After the pulp is treated with xylanase, the flexibility of the fiber increases
due to fine fibrosis on the inside and outside of the paper fiber.

Second, the application of xylanase in the food industry

1.
Bread making
xylanase is mainly used in the food industry to improve wheat flour
.
Zhang Qinliang and others of Jiangnan University studied the effects of different concentrations of neutral xylanase on flour flour quality, baking quality and aging degree during storage, and found that neutral xylanase can significantly improve the powder quality and baking quality of flour.
When the enzyme addition range is 0.
05~0.
48ml/kg (flour), it can increase the anti-aging effect
of bread.

Li Xiuting of Beijing Technology and Business University and others have proved that the quality of bread with appropriate addition of heat-resistant xylanase has been significantly improved, and the aging rate has slowed down, and the aging rate constant has decreased by as much as 48%
compared with the control group.

2.
Lu Dengjun of South
China University of Technology uses xylanase to selectively degrade xylan in raw material sugarcane to prepare functional food additive xylose-oligosaccharides and study
its properties.
The results showed that xylanase enzymatic hydrolysis of raw sugarcane bagasse showed high purity, pure sweetness, good pH stability, thermal stability and excellent preservation performance
.

3.
Xylanase in fruit and vegetable processing
is an important jam enzyme, and the combination of other enzyme preparations can play a good effect
.
Qin Lan and others of Jiangnan University found that carrot juice with xylanase, cellulase and pectinase can be prepared by using mixed enzymes containing xylanase, cellulase and pectinase to prepare carrot juice with certain nutritional value, bright color, good turbidity stability, and no carrot flavor
.
Wang Suya of Jiangnan University and others studied the role of jam enzyme in the clarification process of banana juice, and the results showed that the banana juice obtained by adding jam enzyme to banana pulp for 2 hours at 45 °C was of higher quality, not only did not lose rich nutrients, but also the clarity and yield were effectively improved
.

4.

In the production of liquor, the addition of a variety of polysaccharide hydrolases such as xylanase and cellulase can break the cell structure, so that various active ingredients are more dissolved, and at the same time accelerate the action of amylase, accelerate fermentation, and improve alcohol yield
.
Similarly, exogenous xylanase and related polysaccharide enzymes can effectively improve the quality and production efficiency
of wine in beer and wine brewing.
Xylanase can effectively release cell contents and various hydrolytic enzymes during wort preparation to reduce glycation time
.

Wang Ying of Tianjin University of Science and Technology et al.
discussed the effect of xylanase on alcoholic fermentation of corn raw materials, and the results showed that xylanase was added at the beginning of fermentation, the addition amount was 170U/g, the material-water ratio was 1:2.
5, and when the initial pH value was natural, the wine yield of raw materials increased by 5.
93%, and the fermentation cycle was shortened by 12 hours, which showed that xylanase had a significant promotion effect
on alcoholic fermentation of corn raw materials.

Third, the application of xylanase in feed

Feed generally contains more non-starch polysaccharides (SNSP), mainly including arabinoxylan, β-glucan, α-galactoside, pectin, cellulose, etc.
, of which the first two account for 30%.

The main ones affecting the digestion of nutrients by animals are insoluble non-starch polysaccharides, and xylan is a more important SNSP
.

1.
Wang Xiuqi et al.
of the Institute of Animal Husbandry and Veterinary Medicine, Henan Academy of Agricultural Sciences, Henan Academy of Agricultural Feed
, found that the daily weight gain of wheat diet pigs was significantly positively correlated with the addition of xylanase, and the ratio of feed weight was significantly reduced, and appropriately increasing the amount of enzyme added could improve production performance and economic benefits
.

Feng Dingyuan et al.
of the Academy of Animal Sciences of South China Agricultural University used an enzyme preparation containing xylanase and β-glucanase and other enzymes, using 32.
6 kg weight pig as the test animal, and the diet type was designed according to corn, bean cypress and bran type, and the results showed that the digestibility of crude fiber, crude protein and dry matter increased by 48.
9%, 16.
5% and 11.
3%,
respectively.

Hu Zhongze of Anhui University of Science and Technology applied a complex enzyme preparation containing xylanase, β-glucanase, cellulase, α-amylase, acid protease and mannanase to study the effect
of complex enzymes on the apparent digestibility of dietary nutrients.
The results showed that the apparent digestibility of crude fiber, crude protein and dry matter increased by 36.
76%, 17.
23% and 9.
75%, respectively, while the weight gain and feed conversion rate increased by 8.
29% and 8.
89%, respectively, showing significant or extremely significant effects
.

2.
Cattle and sheep feed
cattle and sheep are ruminants, and the enzyme degradable polysaccharides produced by microorganisms in the rumen are absorbable reducing sugars
.
The addition of exogenous xylanase to feed can improve feed conversion rate
.
When Qi Fenghua et al.
of Shihezi University studied the effect of polysaccharide degrading enzymes on the rumen degradation rate of alfalfa hay nutrients, they set up a control group according to the 4×4 Latin square design, fed the basic diet with 1.
65ml of cellulase, and the experimental L, 2 and 3 groups of diets added xylanase, β-glucanase and pectinase
on the basis of the control group, respectively.
The experimental results showed that compared with the control group, the disappearance rate and effective degradation rate of dry matter, acidic detergent fibers and neutral detergent fibers in alfalfa hay in the 1st, 2nd and 3rd groups of the experiment were significantly improved
.

3.
He Lixia et al.
from the College of Animal Science and Technology of China Agricultural University of Poultry Feed
studied the equivalent value of metabolic energy of two xylanase in five kinds of energy feed and six kinds of laying hen diets, and the results showed that both kinds of xylanase significantly improved the metabolic energy
of laying hens on wheat and corn wheat soybean meal, corn wheat soybean meal cotton meal, corn wheat soybean meal and rapeseed meal type diet.

Yang Guiqin et al.
from the College of Animal Husbandry and Veterinary Medicine of Shenyang Agricultural University added xylanase to meat goose feed, and the test showed that xylanase while relieving the anti-nutritional effect of xylan, the protein in the feed and digestive enzymes interacted strongly, and improved the digestibility
of feed protein 。 When the addition amount was 0.
1%, the activity of endogenous amylase was the highest, which was 20.
57% higher than that of wheat group and 12.
05% higher than that of maize group.
When the addition amount was 0.
2%, the activity of meat goose protease was the highest, which was 34.
48% higher than that of the wheat group and 29.
40%
higher than that of the corn group.

4.
Liu Weicheng et al.
from the School of Life Science and Bioengineering of Ningbo University of Aquatic Feed
added different amounts of xylanase (0.
5‰, 1.
0‰, 1.
5‰) to artificial pelleted feed, and found that it could improve the growth, feeding, conversion efficiency and energy budget distribution rate of juvenile stone bream, and the optimal addition ratio of xylanase was
。
When Zhong Weiwei of Shanghai Ocean University studied the effects of xylanase and complex enzyme preparation PS on the growth performance, digestibility and muscle nutrient composition of Nile tilapia, he added 0.
05%, 0.
10% and 0.
15% doses of xylanase or complex enzyme preparations to the basic feed, and measured the fish body indicators and nutritional composition after 60 days of feeding Nile tilapia, and found that the growth performance and protein digestibility of Nile tilapia reached the maximum when the xylanase amount was 0.
1%.
The growth performance and protein digestibility of Nile tilapia showed an upward trend with the increase of the concentration of PS of the complex enzyme preparation, and the increase was slow when the addition amount was 0.
15%, and the muscle nutrients of the fish were not affected
by the added enzyme.

Fourth, other aspects of application

In terms of biotransformation treatment of waste, xylanase can be used to bioconvert woody fibrous materials into single-cell proteins (SCP), liquid or gaseous fuels such as ethanol, solvents or other useful substances, which has great development potential
.
In addition, xylanase also has a wide range of application prospects
in the decontamination and washing and textile industries.

V.
Prospects

At present, there are still some problems in the direct use of xylanase in industry, such as poor stability, low substrate specificity, short life and high cost
.
As a microbial agent, xylanase has certain requirements
for temperature, humidity and pH.
In order to meet the needs of the application, it is often necessary to screen high-temperature resistant strains, or use genetic engineering and protein engineering to modify the properties of xylanase to meet the requirements
of various factors for xylanase.
In addition, at present, the domestic xylanase activity measurement method is not uniform, and the enzyme activity used is also different, so it is necessary to further unify the national standard
for xylanase activity measurement.
With the deepening of xylanase research, the enzyme will play a greater role
in energy, food, environment and many other fields.