中国科技论文在线 http://www.paper.edu.cn Advanced Materials Research Vols. 197-198 (2011) pp 79-85 © (2011) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMR.197-198.79 Some Characteristics to the Related Food Processing for Garlic Fructan Xuesong Huang 1, a , Min Wang 1, b , Weibin Bai 1, c 1 Department of Food Science and Engineering, Jinan University, 601 Huangpu Ave W, Guangzhou 510632, China [email protected], [email protected], [email protected] Keywords: Fructan,Garlic,Moisture Absorption, Foam Ability, Oil Absorption, Hygroscopy,Gel Abstract. Garlic fructan (GF) is one of the main components of garlic ( Allium sativum L.) and has been largely produced from the residue discharged from getting essential oil in China. Some GF characteristics of the related food engineering, such as solubility, oil absorbability, foam ability, moisture absorption and retention, thermal and acidic stability and the like were investigated. Results showed that GF was soluble in water, slight soluble in ethanol but insoluble in acetone, ethyl acetate or butanol. The precipitation increased as the concentration of alcohol rise. GF presented better oil absorption than casein, as well as higher capacities of moisture absorption and retention in humid and dry environment than glycerin, but lower frothing and foam stability than egg white. GF was not stable at the environment of high acid and temperature. These results provide foundation for the application of GF in liquor, fat substitute food, chemical medicine and other use. Introduction Garlic ( Allium sativum L.), belonging to the Liliaceae family, has attracted the much attention of plant physiologists and chemists [1-2] because of its unique flavor and medicinal functions. For example, the antioxidant properties [3], and therapeutic effects of garlic on atherosclerosis, hyperlipidemia, thrombosis, hypertension and diabetes [4] are well documented in Chian. Most of garlic’s prophylactic and therapeutic effects are ascribed to specific oil- and water-soluble organic sulfur compounds [5-6], which are responsible to the typical odor and flavor [7]. However, the garlic fructan (GF), which is the main component of garlic and made up 75 % of the dry matter [8], has been predicted to account for a significant portion of the pharmacological activities of crushed garlic. In the early 1940s the polysaccharides from garlic were investigated. In the following years the D-fructan was isolated and a linear inulin-type was postulated [9]. In 1981, the differences of the fructan content and synthesis in some Allium species were investigated. The degree of polymerisation (DP) was determined by means of size-exclusion chromatography [10]. Now, GF has been produced from the residue discharged from getting garlic essential oil in industrial scalar in China. It was found that garlic fructan belongs to grammine type and to the neokestose family with a molecular weight of 9000 ~ 10000 Da. DP postulated was about 58. However, Jack [11] extracted oligofructose and fructan from garlic by water and alcohol and analysed their molecular weight in the range of 1000 ~ 4500 Da with a composition of fructose: glucose = 15:1 . Numbers of reports showed the newly potential therapeutic effect of GF in human, such as its liver protection effect in injured mice serum or liver [12], inhibition of lens damages induced by UV irradiation [13], and therapeutic effect on Coxsackie B3 viral myocarditis [14] and so on. All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, 转载 www.ttp.net. (ID: 168.160.159.1-12/02/11,07:09:06) 中国科技论文在线 http://www.paper.edu.cn 80 New and Advanced Materials Meanwhile, GF as the carbohydrate source for lactic acid bacteria [15] makes it as potential prebiotics which may be used to produce the healthy food. However, it is necessary to reorganizate its adaptabilities profoundly for processing characteristics when GF is used in food engineering or pharmaceutical. There are few reports about the research on GF engineering characteristics so far. To set up foundation for GF application, this work described some common food characteristics such as solubility, capacities of oil absorption, moisture absorption and retention, stability in processing, frothing and foam stability so that it could produce high quality food or pharmaceutical excipient based on these engineering characteristics. Materials and methods Raw Material and Reagents. Fresh garlic bulbs were purchased from local Shipai Market, Guangzhou, China. Anhydrous ethanol, sodium hydroxide (N aOH), calcium phosphate (C aHPO 4·2H 2O), ammonium sulfate [(NH 4)2SO 4], sodium carbonate (N a2 CO 3), hydrochloric acid, dinitrosalicylic acid, macro-resin, citric acid and its sodium salt were all purchased from Sigma Aldrich Inc. (St. Louis, MO, USA and Dongzheng Inc. Guangzhou, China) and all analytical purity. Casein, isolated soybean protein and peach gum were food grade and purchased from Dadi Food Additive Co. LTD (Guangzhou, China). Vegetable oil was afforded by Dongzhou oil Co. LTD. GF Preparation. GF was prepared by the method described in the patent [16]. In brief, garlic bulbs were subjected to mild pressure by hand to separate them into cloves. The cloves were crushed and homogenized in a comminuter with distill water. The solution was then gathered through filtration with four layers of gauze, followed by washing with distilled water and squeezing until no additional outflow of milky-white solution occurs. Garlic extract solution was then boiled at 100 ℃ for 20 min to remove the floating impurities before deodorized by chromatography (macro-resin as absorbance) and fined by using acidic silica sol and bentonite as described by Li [17]. The solution was cooled and centrifuged at 3500 r/min for 15 min to discard precipitation. The upper clear solution was collected and spray-dried and the GF powder was collected and used in the following experiments. Solubility of GF. Dissolve 1 g of GF in 10 ml organic solvents, such as ethanol, acetone, ethyl acetate or butanol, to observe the appearance of the mixture liquid. In order to know GF solubility in different ethanol, 2% GF solution prepared, then add 2 ml the solution into each test tube with 20 ml of ethanol in following concentrations (v/v): 10 %, 20 %, 25 %, 30 %, 35 %, and 40 % (v/v). Put them in fridge at 4 ℃ for a week. The precipitation was collected by filtration, dried at 60 ℃ and weighted. Solubility was calculated in 100 ml solution. Capacity of Oil Absorption of GF. Mix 2 g of GF with 10 ml vegetable oil for 30 sec in a Philip mixer (2 L,Royal Philips Electronics,Zhuhai,China). The mixed liquid was then allowed to stand at room temperature (28 ℃) for 30 min. They were thereafter centrifuged for 15 min 3,500 r/min, and the volume of the supernatant noted in a 10 ml graduated cylinder. The volume of dissociated oil in tubes was then observed, represented as V. Calculate the capacity of oil absorption (COA) as formulate below: COA (ml / g) = (10 －V) /2………………………………………………… (1) Foam ability of GF. Accurately weiht 1.5 g of GF and 1.5 g of egg white and dissolve them in 50 ml distilled water separately, and their pH values were adjusted to 7.0 on Model 10 pH meter (Fisher Scient, Derver Instrument Company, USA). The initial volumes of the solutions were recorded as V 0 before mixed. The GF or egg white solution was mixed well by the High Speed 中国科技论文在线 http://www.paper.edu.cn Advanced Materials Research Vols. 197-198 81 Organic Mixer (FHS-2A, Chongqing Jielun Science Technology Trade Development Co. LTD) for 1 min. The foam was transferred to a 100 ml measuring cylinder. The volume of foam (V α) at the following time after the stirring 10 min, 30min, 60 min, 90 min and 120 min was regarded as foam stability. Foam ability (%) ＝(Vα- V0 / V 0 × 100 % …………………………………… (2) Hygroscopy of GF. Weight 0.5 g of GF (dried in drying cabinet till permanent mass) and put them in the inner groove of Conway dish. Saturated (NH 4)2SO 4 and Na 2CO 3 solutions were added in the outer groove of two Conway dish to form an environment with relative humidity (RH) of 81 % and 43 %, respectively. The Conway dishes were then put in an oven which can maintain an invariable temperature at 25 ±0.2 ℃. The mass (M) of GF inside was weighed every 12 h to get the gained moisture weigh ( Δ M). As the blank, weigh 0.5g glycerin in another two Conway utensil and follow the same procedure as mentioned above. Hygroscopy (%) ＝ ΔM / M × 100 % …………………………………(3) Moisture Retention Ability of GF. Weight 0.5 g dry samples and put them in the inner groove of Conway dish then add 0.5 g (m 1) more distilled water and mixed them well. Saturated Na 2CO 3 solutions and dried silic gel were put in the outer groove of Conway dish to form an environment with relative humidity ( RH = 43%) and dried atmosphere, respectfully. The Conway dishes were then put in an oven which can maintain an invariable temperature as 25 ±0.2 ℃. The mass of GF inside was weighed every 12 h to get the gained moisture weight (m 2). Glycerin in other Conway was selected as blank. Use the moisture survival rate (%) to show the moisture retention ability of GF: Moisture survival rate (%) ＝ m2 / m 1 ×100 % ………………………… (4) Gel Formation Ability of GF. Prepare solution of concentration 20 %, 30 % and 40 % (W/V) in order to investigate whether the gel was formed or not. The water release was measured after freezing the solutions as described [18]. Consistence with Macromolecular Materials. Mix 2 ml of 2 % GF solution with 2 ml of 3 % macromolecular materials (Casein, soybean protein, CMC-Na and peach gum) solution, and then put the mixed liquid in KDC low sped centrifuge (Chuangxin Co., Ltd.