高温储藏条件对花生油脂和蛋白质品质劣变的影响

Effect of High Temperature Storage Condition on Quality Deterioration of Peanut Oil and Protein

花生是重要的油料作物,但高油脂含量导致其在恶劣的储藏条件下容易发生品质劣变。为了研究在常规湿度条件下不同储藏温度对花生品质的影响,本实验将带壳花生分别在15、25、35℃条件下储藏30周,并对油脂氧化相关指标(酸价、过氧化值、丙二醛含量)、蛋白质氧化相关指标(羰基、巯基、二硫键含量)以及氧化相关酶类(脂肪酶、脂肪氧化酶、过氧化物酶)活力进行检测。结果表明,从储藏起点到储藏终点,25℃储藏条件下样品的酸价从(0.48±0.01)mg/g上升至(1.78±0.02)mg/g,羰基含量从(3.19±0.24)μmol/g上升至(118.61±6.41)μmol/g。同时,从储藏起点到储藏终点,35℃储藏条件下样品的脂肪酶、脂肪氧化酶活力最高,分别达到(59.00±1.70)U/g和(1287.17±98.45)U/g,酸价从(0.48±0.01)mg/g上升至(3.15±0.10)mg/g,丙二醛含量从23.03 nmol/g上升至1039.63 nmol/g,羰基含量从(3.19±0.24)μmol/g上升至(124.86±3.07)μmol/g。而在15℃储藏条件下,样品脂肪酶和脂肪氧化酶活力最高仅分别达到(41.60±1.23)U/g和(1036.14±34.49)U/g,储藏30周后,过氧化值和羰基含量分别增加18.4倍和17.1倍,各项指标远低于其他温度储藏组。综上,在常规相对湿度下,15℃储藏条件可以有效地将氧化酶类活力始终抑制在较低水平,因此低温储藏下的花生油脂和蛋白质氧化程度较低,而较高的环境温度会提高氧化酶类的活力,且温度越高,酶活力越高,油脂的初级氧化产物、二次氧化产物含量上升,过氧化程度加剧,蛋白质由于氨基酸侧链被氧化和结构破坏等原因一同被氧化,最终导致花生品质下降。

Peanut is an important oilseed crop,susceptible to quality deterioration under harsh storage conditions because of its high oil content.In order to explore the effects of different storage temperatures on peanut quality under normal humidity conditions,in-shell peanuts were stored at 15,25 or 35℃for up to 30 weeks.Indicators of lipid oxidation:acid value(AV),peroxide value(PV),and malondialdehyde(MDA)content;indicators of protein oxidation:carbonyl,sulfhydryl,disulfide bond contents;and the activities of oxidation-related enzymes:lipase(LPS),lipoxygenase(LOX)and peroxidase(POD)were tested.The results showed that the AV increased from(0.48±0.01)to(1.78±0.02)mg/g and the carbonyl content from(3.19±0.24)to(118.61±6.41)μmol/g over the storage period at 25℃.Meanwhile,at the end of storage,the highest lipase and lipoxygenase activities were observed in the sample stored at 35℃,which were(59.00±1.70)and(1287.17±98.45)U/g,respectively;the AV increased from(0.48±0.01)to(3.15±0.10)mg/g,the MDA content from 23.03 to 1039.63 nmol/g,and the carbonyl content from(3.19±0.24)to(124.86±3.07)μmol/g.At 15℃,the highest lipase and lipoxygenase activities were only(41.60±1.23)and(1036.14±34.49)U/g,respectively and the peroxide and carbonyl contents increased by 18.4 and 17.1 times after 30 days of storage,respectively,reaching much lower levels than those at the other temperatures.In conclusion,storage at normal humidity and at 15℃ can effectively suppress the oxidase activity at a low level at all time points,resulting in a low degree of oxidation of peanut oil and protein,while high ambient temperature increases the oxidase activity,and the higher the temperature,the higher the enzyme activity,and the higher the contents of primary and secondary oxidation products in oil,indicating a higher degree of peroxidation.Moreover,protein oxidation also occurs due to the oxidation of amino acid side chains and protein structural damage,ultimately leading to a decline in peanut quality.