RHEOLOGICAL BEHAVIOR OF POMEGRANATE (PUNICA GRANATUM L.) JUICE AND CONCENTRATE

The rheological behavior of pomegranate juice (Punica granatum L.), prepared from fresh pomegranates, was studied as a function of solids concentration in the range 17.5–75°Brix at 10–55C, using a controlled stress rheometer. Concentration methods did not influence flow behavior. There were no significant differences (P > 0.05) between viscosity and activation energy values for the pomegranate juices concentrated by different methods. The juices exhibited Newtonian behavior regardless of the concentration method. The effect of temperature was described by an Arrhenius‐type equation with an activation energy in the range 5.34–32.2 kJ/mol depending on concentration. An exponential model described better the effect of the soluble solids on the viscosity and E_avalues. A simple equation was proposed for describing the combined effect of temperature and soluble solids content on the juice viscosity.     

ANTIOXIDANT PROPERTIES OF THE EXTRACT AND SUBFRACTIONS FROM OLD LEAVES OF TOONA SINENSIS ROEM (MELIACEAE)

The methanolic crude extract and four subfractions (hexane fraction, ethyl acetate fraction, n-butanol fraction and aqueous fraction) of old leaves of Toona sinensis (L.T.S.) were prepared by sequential partitioning, and their antioxidant activities were evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging assay, ferric reducing ability of plasma (FRAP) assay, β-carotene bleaching method and stabilizing soybean oil. The results indicated that old L.T.S. possess powerful antioxidant activity and could prevent oxidation of soybean oil. The ethyl acetate-soluble fraction had the strongest antioxidant activity, with high levels of total flavonoids content (108.57  ±  4.21 mg rutin equivalents/g), total phenol contents (262.09  ±  1.93 mg gallic acid equivalents/g), reductive activity (467.53  ±  6.75 mg ascorbic acid [Vc] equivalents/g), FRAP value (10578.71  ±  149.00 µM FRAP/g) and strong DPPH radical scavenging capacity, respectively. These results suggest that the extract of old L.T.S. is a promising natural alternative to synthetic antioxidants as functional food ingredient and a natural antioxidant in soybean oil.

PRACTICAL APPLICATIONS

Toona sinensis , the popular tree vegetable, is widely cultivated in China. The fresh young leaves and shoots of this plant are nutritious. Every year there are quite a lot of old leaves left and/or discarded after these shoots are consumed. Extracts from old leaves of T. sinensis showed strong antioxidant activity in this study. The strong antioxidant capacity is mainly contributed by the high contents of total flavonoids and total phenolic compounds. Therefore, the total flavonoids and total phenolic compounds could be developed into ingredients of functional foods with antioxidant capacity and as a natural antioxidant for soybean oil.     

ANTIOXIDANT ACTIVITY OF CITRUS HYSTRIX PEEL EXTRACT IN RBD PALM OLEEN DURING FRYING OF FISH CRACKERS

The Citrus hystrix peel extract (2,000 ppm) and butylated hydroxytoulene(BHT) (200 ppm) were added to the frying oil. The antioxidant activities were determined during deep fat frying of fish crackers for 4 consecutive days. Each frying period was for 5 h and intermittent frying at 180C with half an hour interval was carried out. The antioxidant activities were determined by measuring peroxide value (PV), p-anisidine value (AnV), totox value, iodine value (IV), percent free fatty acids, color and viscosity of the oil. Results indicated that the ethanol extract of the citrus peel exhibited antioxidant properties and therefore has a potential as one of the new sources of natural antioxidants.     

果树叶片黄酮抗氧剂的分离及其作用研究

以北方常见果树叶片为原料，经碱性水溶液浸提、浓缩、乙醚萃取、乙酸乙酯二次萃取精制，获得果树叶片黄酮抗氧剂，对应不同种类的叶片收率从2．5％－6．8％，研究了果树叶片黄酮抗氧剂对猪油保存效果，结果发现其抗氧化作用显著。     

甘草甜素废渣中抗氧化物的提取及活性研究

甘草甜素提取后的废渣经95%乙醇粗提,索氏梯度提取,部分组分pH梯度萃取及硅胶薄层纯化,全过程辅以结构定性和抗氧化活性跟踪。结果表明,各组分均有很强的抗氧化作用,其中以乙酸乙酯提取物活性最高,其经5%Na2CO3处理后活性明显增大,为合成抗氧化剂BHT的1.28倍,它与BHT复配(1:1)后其抗氧化效果升高为原来的2.62倍,说明了二者之间有很好的协同作用。     

蒜粉体外抗氧化活性研究

主要对采用微波真空与真空联合干燥法得到的大蒜片粉碎成蒜粉后的抗氧化活性进行了研究,分别采用四种不同的体外抗氧化模型:·OH体系、O2.-体系、DPPH.体系、红细胞膜脂质过氧化体系等,检验蒜粉的抗氧化能力。结果表明,蒜粉在这四种体外抗氧化模型中均表现出较高的抗氧化性,且其浓度与抗氧化活性呈一定的量效关系。     

橙皮中果胶的最佳提取方法及工艺研究

探讨乙醇沉淀法和盐析法两种方法从橙皮中提取果胶,获得提取橙皮中果胶的适宜方法和条件为乙醇沉淀法在果胶提取液选用盐酸,PH值为2.5,提取液为120mL,醇析温度90℃,醇析静置时间2h.     

THE STIMULATION OF PHENOLICS AND ANTIOXIDANT ACTIVITY IN PEA (PISUM SATIVUM) ELICITED BY GENETICALLY TRANSFORMED ANISE ROOT EXTRACT

A series of dark germination experiments demonstrate the potential of an Agrobacterium rhizogenes‐transformed, high cytokinin root extract of anise (Pimpinella anisum), to stimulate phytophenolic and enhance antioxidant activity in pea (Pisum sativum) seedlings. Average shoot weight increased 40–60% after imbibing seeds for 24 h in a 1.5 to 2.0% extract of the anise root clone AR‐10. Phenolic concentration was positively correlated with shoot weight, suggesting that the total phenolic content was related to seedling vigor. Antioxidant protection factor in pea shoots was also stimulated by AR‐10 extracts. Free proline concentrations were 2–3 times higher in shoots collected from AR‐10 treated peas versus controls. However, proline content also increased as shoot weight declined after being subjected to an overdose of AR‐10 extract in 25% ethanol. G6PDH specific activity, the first committed step of the pentose phosphate pathway, was negatively associated with shoot growth and proline concentrations.     

ANTIOXIDANT ACTIVITY AND TOTAL PHENOLIC CONTENTS IN PEEL AND PULP OF CHINESE JUJUBE (ZIZIPHUS JUJUBA MILL) FRUITS

Total phenolic contents in peel and pulp of the fruits of three Chinese jujube cultivars ( Ziziphus jujuba cv. mayazao, Z. jujuba cv. dongzao and Z. jujuba cv. yuanzao) were determined. The antioxidant activities in peel and pulp of the jujube fruits were measured by different methods, including 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity, ferric reducing antioxidant power (FRAP) and Trolox equivalent antioxidant capacity (TEAC). The total phenolic content in peel was five to six times higher than that in the pulp of all the three cultivars. The phenolics contents in the jujube were different with cultivars. The EC₅₀ ( Concentration of lyophilized samples needed to decrease the initial DPPH radical concentration by 50% ), FRAP and TEAC values of the peel and pulp were remarkably correlated to their total phenolic contents (R  = − 0.922, R  =  0.985 and R  =  0.997, respectively). The results indicated that the high capacity of antioxidant of Chinese jujube fruit could be attributed to the high phenolic contents in the fruit.

PRACTICAL APPLICATIONS

There was an expanding quest surrounding the use of antioxidant because they have the capacity to protect from the damage because of free radicals and reactive oxygen species. However, the safety of synthetic antioxidant was challenged. Much attention has been focused on the use of natural antioxidant. Interest in food phenolics had increased greatly because of their antioxidant and possible promoting-health role in human health. In this study, total phenolic contents and antioxidant capacities in vitro of Chinese jujube ( Ziziphus jujuba Mill) peel and pulp were researched. The work would help to explore a natural antioxidant for possible application in food and dietary supplemental products for health promotion.     

不同处理措施对草莓汁加工过程中Vc保存率的影响

以新鲜草莓果实为原料，对草莓汁加工过程中的Vc含量变化及其控制方法进行了研究。结果表明，快速清洗有利于草莓果中Vc的保存；微波热烫较热水热烫的Vc保存率高；热压榨方式有利于保持草莓的Vc含量；草莓汁灭菌时采用90℃灭菌15min的效果最好，灭菌后快速冷却有利于草莓汁中的Vc保存。