超高压对鲜切胡萝卜硬度的影响及机制研究

鲜切果蔬的品质在加工后易受到破坏,超高压技术(high pressure processing,HPP)在鲜切果蔬品质保持方面具潜力。旨在探究鲜切果蔬的硬度随压力变化的规律及硬度变化的机制。本文以胡萝卜为对象,研究了超高压(100~600 MPa,5 min)对鲜切胡萝卜硬度、细胞膜完整性、果胶甲酯酶(pectin methylesterase,PME)及细胞壁果胶组成的影响。100 MPa处理后胡萝卜硬度无显著变化,随着压力增加,胡萝卜相对电导率显著增加,硬度显著下降,当达到300 MPa后,尽管压力继续升高,相对电导率和硬度变化已不显著;同时,高压处理后碱溶性果胶(sodium carbonate soluble pectin,NSP)增加,水溶性果胶(water soluble pectin,WSP)下降,但高压不能充分钝化果胶甲酯酶。超高压处理后细胞膜透性的改变和细胞壁果胶组分的变化共同影响了鲜切胡萝卜的硬度。 

Study on effect and mechanism of high pressure processing on hardness of fresh-cut carrot

Processing methods always cause damage to fresh-cut fruits and vegetables. High pressure processing ( HPP) is promising a technology for protecting the quality of fresh-cut fruits and vegetables. In order to explore the hardness change of fresh-cut fruits and vegetables with the increased pressure and the corresponding internal mechanisms.This study was designed to evaluate the effect of high pressure processing ( 100 ~ 600 MPa, 5 min) on the changes in hardness, cell membrane, pectin methylesterase ( PME) and cell wall pectin fraction of fresh-cut carrot.The results showed that there was no significant change in carrot hardness after 100 MPa treatment, and the relative conductivity and the hardness of carrots increased significantly with the increase of pressure.When the pressure reached 300 MPa, the relative conductivity and hardness no longer alter significantly even if increased pressure.Meanwhile, increase in sodium carbonate soluble pectin ( NSP) and decrease in water soluble pectin ( WSP) fraction at all pressure levels were observed.However, complete inactivation of pectin methylesterase activities could not be fulfilled by HPP. Hardness change of fresh-cut carrot processed by HPP was attributed to changes of cell membrane permeability and cell wall pectin components profile.