Studies On Physicochemical Properties Of Potato Pulp With Enzyme Treatment And Application As Feed Component

Potato pulp is one of the main by-products during potato starch processing. The potato pulp with high water holding capacity is not easy for storage. If not recycled, the pulp will not be only a waste of resources, but also cause serious environmental pollution. Potato residue utilization rate is low, and its processing has not effectively settled. And the potato residue after processing as a feed component added is a promising direction for potato pulp. This paper adopted potato pulp as raw material, and the residual starch was dealed withα-amylase. Different functional properties were shown in these samples after hydrolysis which releases cellulose better from the pulp to play a role, and to solve the problem of palatability and digestibility by enzymatic. The synergy of cellulose and starch hydrolysates promotes animal growth, and ferments selectively of the intestinal flora in the digestive tract after paragraph. Then it was been added into feed by replacing some wheat bran, and the effects of feed with hydrolyzed potato pulps on growth performance and intestinal flora of rats were investigated. Firstly, the ingredients and hydrolysis process of potato pulp were determined.Determination of composition of the potato pulp showed that it had high water content, the main ingredients were starch, cellulose, pectin, protein, ash and so on. The potato pulp was dealed withα-amylase, and cellulose could release better by the starch hydrolysis, and adjusted the pH to 4 for enzyme inactivation. Then kinds of degree of hydrolysis of samples were got, DE value was determined by measuring the reducing sugar content. The results showed that: Potato residue moisture content was about 73.6 %, and dry basis of the main components was starch 35.4 %,cellulose 15 %,hemicellulose 30 %,pectin 12.1 %,protein 1.6 %,ash 0.4 %. By adjusting the amount of enzyme added, kinds of hydrolysates with different DE values 6,11,14,18,22 were prepared.Secondly, the characterization and properties of different DE values of potato potato were analysised. Scanning electron microscope showed that enzymolysis made the struture looser, and the close engagement state of starch and cellulose was destroyed which was favorable for cellulose to play a beneficial role. The chemical composition and crystalline structure of potato pulps of different DE value were studied by FTIR and XRD. The results showed that the hydrolyzed potato pulps did not change compared with that of untreated, but the effect of the change of the separated cellulose and starch on the surface for the properties of micro-structural changes of potato residue should not be overlooked. Higher values of ion exchange capacity, cellulose conversion ratio, digestibility, expansibility, water-and oil- holding rate were found in potato pulp after treatment by enzyme treatment. And that higher emulsifying activity with high emulsion stability was shown in hydrolyzed potato pulps. Some indicators that not conducive to growth and digestion, such as amylase inhibition and glucose binding ability, increase with the deepening of the enzymatic hydrolysis extent. Therefore, from the point of view as the feed, considering the properties of potato pulp, choosing some moderate degree of hydrolysis of the sample (DE = 14) for feed was more appropriate.At last, the DE value of 14 of potato pulp by enzyme was added into feed instead of 5 % wheat bran with the residue and that not added as control. At the same conditions of feeding, the effects of feed with hydrolyzed potato pulps on growth performance and intestinal flora of rats were investigated and the feed cost was accounted. The results showed that: Rats fed with feed which contained hydrolyzed potato pulps (hydrolysis group) gained higher increase in weight than control and those fed with feed containing untreated potato pulps (untreated group) and significant difference could be found during the first 7 days. The number of lactoacillus in enzymatic group ileum, cecum, colon contents and on the corresponding mucous membranes was significantly higher than control untreated group. The number of E. coli in enzymatic group ileum, cecum, colon contents and on the corresponding mucous membranes was significantly smaller than control dprotoplasmic group. Enzymatic group intestines better, and get higher water content in rat feces. Besides, the enzyme group has lower feed cost advantage.