The effect of ultrasound on enzymatic degumming process of ... - Core

Ultrasonics Sonochemistry 21 (2014) 142–148

Contents lists available at ScienceDirect

Ultrasonics Sonochemistry journal homepage: www.elsevier.com/locate/ultson

The effect of ultrasound on enzymatic degumming process of rapeseed oil by the use of phospholipase A1 q Xiaofei Jiang, Ming Chang, Xiaosan Wang, Qingzhe Jin, Xingguo Wang ⇑ School of Food Science and Technology, Jiangnan University, State Key Laboratory of Food Science and Technology, 1800 Lihu Road, Wuxi 214122, Jiangsu, PR China

a r t i c l e

i n f o

Article history: Received 7 June 2013 Received in revised form 15 July 2013 Accepted 31 July 2013 Available online 23 August 2013 Keywords: Phospholipase A Degumming Ultrasound Rapeseed oil

a b s t r a c t Comparative studies of enzymatic degumming process of rapeseed oil were carried out in mechanicalstirring and ultrasonic-assisted mechanical-stirring systems. The influences of enzyme dosage (10–50 mg/kg), pH (4.5–6), temperature (45–65 °C), water amount (1–3%), ultrasonic power (0.06– 0.09 W/cm3) and reaction time were investigated subsequently. A suitable ultrasonic power of 0.07 W/ cm3 was determined to guarantee satisfactory degumming efficiency and enzyme activity. Compared to the mechanical-stirring system, optimum temperature of phospholipase A (PLA) in the ultrasonicassisted mechanical-stirring system was about 5 °C higher, while the effects of pH on both of the two systems were quite similar. Less time and water were used in the ultrasonic-assisted mechanical-stirring system for enzymatic degumming. The study on the quality changes of degummed oils showed that ultrasound could accelerate the oxidation of edible oils due to the effect of cavitation, thus more attention should be paid on the oxidative stability in the further application. Ó 2013 The Authors. Published by Elsevier B.V. All rights reserved.

1. Introduction Rapeseed is one of the most important oilseed crops and a major source of edible vegetable oil in China. The planting area of the rapeseed is about 6.7 million hectares, and the total yield is about 12 million tons, accounting for 20% of the world’s supply [1]. To obtain edible vegetable oils from oil-bearing seeds such as soybean, rapeseed, peanut or sunflower, various refining operations are required. Degumming is the first step in the refining process of vegetable oils, which removes phospholipids and mucilaginous gums. The presence of substantial amounts of phospholipids can cause oil discoloration and serve as a precursor of off-flavors. Therefore, the removal of nearly all of the phospholipids is essential for the production of high-quality finished oil [2]. Traditional degumming processes, including water degumming, super-degumming, total degumming, acid treatment, etc., cannot guarantee the achievement of low phosphorus contents ( 0.05), but showed a significantly higher value compared with crude oil, increasing from about 3.24 mmol/kg to about 4.20 mmol/kg (P 6 0.05). It meant that the crude oil was partially oxidized during the enzymatic degumming process. Compared to the crude oil, metal ions (Fe, Ca and Mg) in both of the two enzymatic degumming systems were significantly decreased in combination with the removal of phospholipids. It is well know that the removal of metal ions would improve the oxidative stability of degummed oil, because the existence of the metal ions, such as Fe, was a promoter for the automatic oxidation of oil. However, in our study, the oxidative stability of crude rapeseed oil was better than that of degummed oils with different kinds of degumming treatments (P 6 0.05), which might be explained that phospholipids were a kind of natural antioxidants and could postpone the rate of oil oxidation [19]. In addition, compared to the sole mechanical-stirring treatment, ultrasonic treatment could further reduce the oxidative stability of the degummed oil. The result was in compliance with other researchers to some extent, indicating that ultrasound treatment could accelerate the oxidation of edible oils [20]. The ultrasonic oxidation of degummed oil might be attributed to the effect of cavitation. Metals which existed naturally in edible oils, in combination with ultrasound cavitation, could be suspected as a possible responsible for the formation of oxy-radical species to induce the oxidation of rapeseed oils. 4. Conclusion The present study showed that ultrasonic-assisted treatment could accelerate the enzymatic reaction rate and enhance the enzymatic degumming efficiency of rapeseed oil. Both the optimum temperature and inactivation temperature of PLA under ultrasound irradiation were higher than those without ultrasound treatment. The treatment of ultrasound did not change the pH-pattern of PLA, and less water was required to saturate the substrates under ultrasonic-assisted mechanical-stirring system. Quality analysis of the degummed oils showed that ultrasonic-assisted treatment did not significantly change the PV value of degummed rapeseed oil (P > 0.05), which meant that the rate of primary

Table 1 Overview of the FFA, metal ions and oxidative stability of degummed rapeseed oils after different kinds of treatment. Parameters Phosphorous content (mg/kg) FFA (g/100 g) a PV (mmol/kg) Minerals (mg/kg) Fe Ca Mg Oxidative stability (h)

Mechanical-stirringb

Crude

Ultrasonic-assistedc

A

252.05 ± 0.91 2.08 ± 0.05A 3.24 ± 0.08A

B

7.52 ± 0.48 2.35 ± 0.06B 4.16 ± 0.07B

6.49 ± 0.4C 2.38 ± 0.08B 4.22 ± 0.10B

7.32 ± 0.24A 66.53 ± 1.86A 43.81 ± 2.10A 5.38 ± 0.17A

2.99 ± 0.32B 8.07 ± 1.22B 3.73 ± 0.67B 4.61 ± 0.18B

3.08 ± 0.25B 7.37 ± 1.46B 3.34 ± 0.52B 4.21 ± 0.11C

The letters of A, B and C represent the differences among different treatments: the same letter indicates no significant difference (P > 0.05), different letters indicate a significant difference (P 6 0.05). a Expressed as oleic acid. b Mechanical-stirring system: pH = 5.0, enzyme dosage = 40 mg/kg, water amount = 3% (relative to the weight of oil), reaction temperature = 50 °C, reaction time = 5 h. c Ultrasonic-assisted mechanical-stirring system: pH = 5.0, enzyme dosage = 40 mg/kg, water amount = 2.5% (relative to the weight of oil), reaction temperature = 55 °C, reaction time = 3 h, ultrasonic power = 0.07 W/cm3.

148

X. Jiang et al. / Ultrasonics Sonochemistry 21 (2014) 142–148

oxidation did not change a lot compared with sole-mechanicalstirring treatment. However, evaluation of oxidative stability under Rancimat accelerated oxidation condition showed that ultrasound treatment could accelerate the oxidation of edible oils due to the effect of cavitation. These results indicate that ultrasound could be an effective way to reduce the time, water and enzyme dosage used in PLA degumming process, but more attention should be paid on oxidative stability of oils in further application. Acknowledgements The work is supported by Key Projects in the National Science & Technology Pillar Program during the 12th Five-Year Plan Period of China (Contract No: 2011BAD02B03), the Fundamental Research Funds for the Central Universities (JUSRP11226) and supported by the Major State Basic Research Development Program of China (973 Program, 2012CB720802, 2012CB720806). References [1] M. Yang, C. Zheng, Q. Zhou, F. Huang, C. Liu, H. Wang, Minor components and oxidative stability of cold-pressed oil from rapeseed cultivars in China, J. Food Compos. Anal. 29 (2013) 1–9. [2] R. Zamora, C. Olmo, J.L. Navarro, F.J. Hidalgo, Contribution of phospholipid pyrrolization to the color reversion produced during deodorization of poorly degummed vegetable oils, J. Agric. Food Chem. 52 (2004) 4166–4171. [3] A.J. Dijkstra, M. Van Opstal, The total degumming process, J. Am. Oil Chem. Soc. 66 (1989) 1002–1009. [4] J.G. Yang, Y.H. Wang, B. Yang, G. Mainda, Y. Guo, Degumming of vegetable oil by a new microbial lipase, Food Technol. Biotechnol. 44 (2006) 101–104. [5] A.J. Dijkstra, Enzymatic degumming, Eur. J. Lipid Sci. Technol. 112 (2010) 178–1189. [6] K. Clausen, Enzymatic oil-degumming by a novel microbial phospholipase, Eur. J. Lipid Sci. Technol. 103 (2001) 333–340.

[7] F. Jiang, J. Wang, I. Kaleem, D. Dai, X. Zhou, C. Li, Degumming of vegetable oils by a novel phospholipase B from Pseudomonas fluorescens BIT-18, Bioresour. Technol. 102 (2011) 8052–8056. [8] M. Jahani, M. Alizadeh, M. Pirozifard, A. Qudsevali, Optimization of enzymatic degumming process for rice bran oil using response surface methodology, LWT- Food Sci. Technol. 41 (2008) 1892–1898. [9] B. Yang, R. Zhou, J.G. Yang, Y.H. Wang, W.F. Wang, Insight into the enzymatic degumming process of soybean oil, J. Am. Oil Chem. Soc. 85 (2008) 421–425. [10] L.D. Maria, J. Vind, K. Oxenbøll, A. Svendsen, S. Patkar, Phospholipases and their industrial applications, Appl. Microbiol. Biotechnol. 74 (2007) 290–300. [11] S. Mukataka, T. Kobayashi, J. Takahashi, Kinetics of enzymatic hydrolysis of lipids in biphasic organic-aqueous systems, J. Fermentation Technol. 63 (1985) 461–466. [12] T. Mason, L. Paniwnyk, J. Lorimer, The uses of ultrasound in food technology, Ultrason. Sonochem. 3 (1996) S253–S260. [13] C. Li, M. Yoshimoto, H. Ogata, N. Tsukuda, K. Fukunaga, K. Nakao, Effects of ultrasonic intensity and reactor scale on kinetics of enzymatic saccharification of various waste papers in continuously irradiated stirred tanks, Ultrason. Sonochem. 12 (2005) 373–384. [14] C. Li, M. Yoshimoto, N. Tsukuda, K. Fukunaga, K. Nakao, A kinetic study on enzymatic hydrolysis of a variety of pulps for its enhancement with continuous ultrasonic irradiation, Biochem. Eng. J. 19 (2004) 155–164. [15] Y. Liu, Q. Jin, L. Shan, Y. Liu, W. Shen, X. Wang, The effect of ultrasound on lipase-catalyzed hydrolysis of soy oil in solvent-free system, Ultrason. Sonochem. 15 (2008) 402–407. [16] B. Yang, Y.H. Wang, J.G. Yang, Optimization of enzymatic degumming process for rapeseed oil, J. Am. Oil Chem. Soc. 83 (2006) 653–658. [17] D. Bezbradica, D. Mijin, S. Siler-Marinkovic, Z. Knezevic, The Candida rugosa lipase catalyzed synthesis of amyl isobutyrate in organic solvent and solventfree system: A kinetic study, J. Mol. Catal. B: Enzyme 38 (2006) 11–16. [18] M. Sakakibara, D. Wang, R. Takahashi, K. Takahashi, S. Mori, Influence of ultrasound irradiation on hydrolysis of sucrose catalyzed by invertase, Enzyme Microb. Technol. 18 (1996) 444–448. [19] M. Kashima, G.S. Cha, Y. Isoda, J. Hirano, T. Miyazawa, The antioxidant effects of phospholipids on perilla oil, J. Am. Oil Chem. Soc. 68 (1991) 119–122. [20] F. Chemat, I. Grondin, P. Costes, L. Moutoussamy, A. Sing, J. Smadja, High power ultrasound effects on lipid oxidation of refined sunflower oil, Ultrason. Sonochem. 11 (2004) 281–285.