Study On Physicochemical Properties And Colloid Stability Of Goat Milk

Using Saanen goat milk as material, the composition of basic contents,composition and nutritional value of amino acids, fatty acids and mineral elements ofgoat milk were analyzed by amino acid automatic machine, ICP, GC. Physicochemicalproperties and stability of goat milk also was comprehensively researched. The purposeof this article is to make the best of the goat milk and exploit functional products. Theresearch resultswere as follows:1. The physicochemical properties of goat milk were detected in the paper. Theresults showed that goat milk was white which hold sweet tasting and goat flavor whenit was heated. Mean values of pH, specific gravity, acidity in goat milk were: 6.70,1.028, 0.130(%), 13.38°T. Mean total solid, total protein, fat, lactose, ash and NPN ingoat milk were: 14.36%, 3.98%, 4.25%, 4.12%, 0.74%, 8.23%; the total contents of18 amino acids were 3774mg/100mL, average contents were 210mg/100mL, the totalcontents of 8 essential amino acids were l137mg/100mL. Average contents were142mg/100mL, the ratios of 8 essential amino to total amino acids were 30.13%. Thereare abundant saturated fatty acid in goat milk, the contents of saturated fatty acid were67.50% of fatty acid, lower acid contents were 36.17% of saturated fatty acid, especiallyacetic acid contents was very high compare with milk. The were rich mineral elements,the contents of Ca, Mg, P, K were very high, the contents of Cu, Fe, Mn, Zn were alsohigh, while the contents of Na was low. Isoelectric point of goat milk is 4.3. Heatingbody system of casein, the rate of position increased as the increase of Ca²⁺, and thelower concentration, the higher temperature.. The heat coagulation time(HCT) of goatmilk albumin were 80℃-60min, 85℃-42.5min, 90℃-30min, 95℃-12.5min,100℃-10min; mean values of acid value, iodine value, saponification value for goatmilk were: 1.24mgKOH/g, 26.0g/100g, 236.0mgKOH/g.2. Study on the heat stability of goat milk at differ factors showed that: as the pH isincreased, the heat stability increase to a maximum at about pH 6.90 and followed by adecrease at higher pH. The heat stability of natural goat milk samples (pH=6.70) wasmarkedly lower the maximum values at about pH 6.90. From 120℃to 145℃, as thetemperature increased, the heat stability decrease to lower values. The heat stability of goat milk showed a markedly low trend with the addition of Ca²⁺. The addition ofchelating agent to goat milk samples markedly increased the heat stability. The heatstability of goat milk samples showed more better the heat stability by addition of0.5g/L Na₂HPO₄, Na₅P₃O₁₀, Na₄P₂O₇, and 0.3g/L NaH₂PO₄, Na₃C₆H₅O₇.2H₂O,EDTA-2Na to the goat milk samples before processing. Comparing with collation, bankof chelating agent can increase markedly the heat stability of goat milk. There aredifference influences on heat stability of goat milk between six kinds of chelating agents.And sequences of efficiency to the heat stability for chelating agent were: Na₅P₃O₁₀＞Na₂HPO₄＞Na₄P₂O₇＞Na₃C₆H₅O₇.2H₂O＞NaH₂PO₄＞EDTA-2Na.3. Study on ethanol stability of goat milk showed that goat's milk samplesprecipitated upon addition of an equal volume of 44% ethanol, whereas fresh cow'smilk typically precipitates at 70% ethanol addition. Ethanol stability of goat milkincreases with increasing pH values (6.4～7.2) and decreases with addition of Ca²⁺(0.1～0.6g/L). In contrast, the increase of temperature resulted in decreasing ethanolstability. The addition of chelating agents form (Na₅P₃O₁₀, Na₄P₂O₇, Na₂HPO₄,Na₃C₆H₅O₇.2H₂O, NaH₂PO₄) can increase markedly ethanol stability of goat milk andincrease the pH values at the same time. Differences chelating agents have differencesefficiency to ethanol stability of goat milk. Ethanol stability of goat milk increases withincreasing concentration of the same chelating agent. Comparing with collation, bank ofchelating agent can increase markedly the ethanol stability of goat milk. There aredifference influences on ethanol stability of goat milk between six kinds of chelatingagents. And sequences of efficiency to the ethanol stability for chelating agent were:Na₅P₃O₁₀＞Na₄P₂O₇＞Na₃C₆H₅O₇.2H₂O＞Na₂HPO₄＞NaH₂PO₄＞EDTA-2Na.4. Study On coagulating property of goat milk showed that the coagulation time ofgoat milk increased with pH (6.4～7.2) values and decrease,: with addition of Ca²⁺(0.01～0.06g/L). The addition of chelating agents form(Na₅P₃O₁₀, Na₄P₂O₇,Na₂HPO₄, Na₃C₆H₅O₇.2H₂O) can increase markedly the coagulation time of goat milkand increase the pH values at the same time. Differences chelating agents havedifferences efficiency to coagulating property of goat milk. Coagulation time of goatmilk increases with increasing concentration of the same chelating agent. Comparingwith Collation, bank of chelating agent can increase markedly the coagulation time ofgoat milk. There are difference influences on coagulating property of goat milk betweensix kinds of chelating agents. And sequences of efficiency to the coagulating time of goat milk for chelating agent were: Na₅P₃O₁₀＞Na₄P₂O7＞Na₂HPO₄Na₃C₆H₅O₇.2H₂O＞NaH₂PO₄＞EDTA-2Na.