Study On Preparation And Properties Of Food Additives Of Medium Chain Fatty Acid Esters

The developing of modern food industry is result from the use of food additives. With the development of living, people desire food not only delicious but also nutritious. Medium-chain fatty acid esters can rapidly supply energy and reduce Serum cholesterol, so developing this kind of food additives is in line with the demanding of people.Camphor tree seed oil is rich in medium chain fatty acid (decanoic and lauric acid), so it is ideal material to synthesize medium chain fatty acid esters.In this paper, sodium medium chain fatty acid fatty-acyl lactylate, medium chain monoglycerol were prepared from camphor tree seed oil.The emulsifying function of sodium medium chain fatty-acyl lactylate, and antibacterial function and mechanism of medium chain monoglycerol were also investigated.The optimum preparation conditions of sodium medium chain fatty acid fatty-acyl lactylate catalyzed by p-toluene sulphonic acid absorbed in active carbon are as follow:ratio of sodium lactate to fatty acid of 2:1,4%catalyst, reaction time 60 min and reaction temperature 180℃.The synthesis rate of medium chain sodium fatty-acyl lactylate sodium lactate under these conditions were determined to be 95.6%, and the catalytic activity of P-toluene sulphonic acid absorbed in active carbon did not significantly decrease after 5 times reusage.The physical and chemical properties of sodium medium chain fatty acid fatty-acyl lactylate were analyzed by FAO/WHO standard to Sodium stearyl lactate and the results were:ester value 220, acid value 0.8, solidification point 52℃, lactic acid 35%. The emulsifying function of sodium medium chain fatty acid fatty-acyl lactylate were tested by GB/T11543-2008 standard to surface active agent and the results were as follow:Medium chain monoglycerol have a strongest emulsifying power when oil-water ratio was3'.7 and then it can reach to 81.1g/g. The using amount of medium chain monoglycerol to form stable emulsion at centrifugating condition was 4%, that at room temperature was 3%and at high temperature was 5%.At the same time, monostearin was set as control in this test. The result showed that emulsion form by medium chain monoglycerol was better than that by monostearin.The optimum transesterification conditions to prepare medium chain monoglycerol catalyzed by concentrated sulfuric acid were:reaction temperature 170℃, time 3.Oh, molar ratio glycerol to oil 5:1, amount of catalyst 1.5%(oil weight). Under this conditions monoglycerides yield can reach to76.0%.Medium chain monoglycerol can inhibit all microorganism of E. coil, S.aureus, B.subtilis, S.cerevisae and A.niger. The minimum inhibition concentration(MIC) of Medium chain monoglycerol to testing bacteria were as follow:E.coil 1.25mg/L, S.aureus 0.32 mg/L, B.subtilis 0.32 mg/L, S.cerevisae 0.32 mg/L and A.niger 0.32 mg/L. The change of pH of environment will not reduce or increase its inhibition to bacteria. In contrast, the antibacterial function of medium chain monoglycerol is better than other preservatives such as NISIN, potassium sorbate and butyl p-hydroxybenzoate.In this work, we further explored the antibacterial mechanism of medium chain monoglycerol against tested bacteria. The membrane permeability of tested bacteria were characterized by using orescein diacetate (FDA) as fluorescent indicator, the leak of internal substance of tested bacteria, such as:protein, nucleic acid, lipopolysaccharide, K+, Ca2+and Mg2+, were investigated using Spectropbotometry Method. The respiration of cell was analyzed by oxygen electrode method. The change of cell construct were characterized by electron microscope.The result indicate that medium chain monoglycerol can increase the membrance permeability, provoke internal substance leaking, hamper cell respiration, destruct cell wall and cell membrane.