芹菜不同品种类型间营养成分及抗氧化活性差异

为研究芹菜不同品种类型间营养成分及抗氧化活性差异,采集旱芹、水芹、西芹和白芹四种芹菜样品,检测其维生素C、5-甲基四氢叶酸及叶酸、胡萝卜素、总酚、总黄酮及酚酸含量,并确定其抗氧化活性差异。结果表明,水芹中维生素C及总酚含量最高,白芹中叶酸总量最高,旱芹中总胡萝卜素含量最高,水芹、白芹和旱芹中总黄酮量均高且彼此无显著性差异,水芹和白芹中酚酸总和最高且无显著性差异,西芹中维生素C、总酚、总黄酮及酚酸总和均为最低。抗氧化活性评价显示,DPPH以及ABTS自由基清除率均以水芹最高,其次分别为旱芹和白芹。FRAP还原能力以旱芹最高,其次为白芹和水芹。西芹在三种评价方法中抗氧化活性均为最低。水芹、白芹及旱芹营养成分各有突出特点,且具有较高抗氧化活性,这对特定人群高营养蔬菜品种类型推荐以及居民营养物质饮食摄入风险评估具有指导意义。     

ANTIOXIDANTS IN ONION (ALLIUM CEPA L) CULTIVARS GROWN IN INDIA

Health benefits of phenolics are prompting vegetable breeders to identify cultivars with enhanced functional properties. Ten onion cultivars grown under North Indian conditions were evaluated for their total phenolics, flavonoids, quercetin and total antioxidant activity for two consecutive years. Total phenolics, flavonoids and antioxidant activity exhibited significant variation ( P <  0.05) among cultivars. Red cultivars, namely Sel-383, N-53, Pusa red and Sel-402, constituted a high phenolic group, with a mean content higher than 100 mg/100 g gallic acid equivalents. Mean flavonoid content was highest in cultivars, Pusa red, Sel-402, H-44 and N-53 ( > 40 mg/100 g). White cultivars namely, Pusa white flat, Pusa white round and Early grano, consistently showed low phenolics, flavonoids and total antioxidant activity. Total antioxidant activity as determined by ferric reducing antioxidant power (FRAP), cupric reducing antioxidant capacity (CUPRAC) was highest in cultivars Sel-383, N-53, Pusa red and Sel-126. Over both consecutive years, phenolics correlated positively with total antioxidant activity ( R ²  =  0.95 FRAP and R ²  =  0.87 CUPRAC). Over all red cultivars, Sel-383 and Pusa red are promising cultivars for incorporation in existing breeding programs for the production of onions with high antioxidant content.

PRACTICAL APPLICATIONS

Onion, being a major constituent of Indian diet, is a potential source of phenolics and flavonoids. Selection of the phenolic-rich cultivars, preferably the red ones with high antioxidant activity, can deliver a variety of health benefits. The breeders can use total phenolics and flavonoids as parameters to develop varieties with increased levels of target antioxidants.     

东北6 种红树莓叶酚类化合物的鉴定及抗氧化活性分析

以东北地区6 种不同品种的红树莓营养叶片为原料,采用分光光度法测定总酚、总黄酮和原花青素含量;使用3 种方法评价体外抗氧化活性并分析抗氧化活性与总酚、总黄酮和原花青素含量的相关性;采用超高效液相色谱-串联质谱法鉴定多酚类物质。结果表明,6 种红树莓叶片总酚含量高于总黄酮与原花青素含量。欧洲红的总酚与总黄酮含量最高,分别为（5.56±0.06）mg/g和（3.77±0.06）mg/g;哈瑞泰兹的原花青素含量最高为（3.06±0.04）mg/g。3 种抗氧化能力评价方法中,红树莓叶提取物对2,2’-联氮-双-(3-乙基苯并噻唑啉-6-磺酸二铵盐)（2,2’-azino-bis(3-ethylbenzthiazoline-6-sulphonate),ABTS）阳离子自由基清除能力与1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基清除能力具有极显著正相关性,相关系数为0.992;红树莓叶提取物中总酚含量和对ABTS阳离子自由基清除能力与对DPPH自由基清除能力的相关性显著,相关系数分别为0.886和0.891。超高效液相色谱-串联质谱法检出红树莓叶提取物中的13 种多酚类物质,其中有6 种酚酸和7 种类黄酮,主要酚酸为鞣花酸、绿原酸、没食子酸等;主要类黄酮为芦丁、儿茶素、表儿茶素、金丝桃苷等。     

青钱柳叶活性成分的抗氧化活性及UPLC-QTOF-MS/MS分析

利用96孔板法测定青钱柳叶不同溶剂(水、70%乙醇、乙酸乙酯和正己烷)提取物中总酚、总黄酮含量及抗氧化活性(DPPH自由基清除能力、还原能力、总抗氧化能力),考察酚类物质含量与抗氧化活性的相关性,并采用超高效液相色谱-四极杆飞行时间串联质谱(ultra performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spetrometry,UPLC-QTOF-MS/MS)分析提取物中主要活性成分。结果表明:不同提取物中总酚、总黄酮含量及抗氧化活性存在显著性差异且70%乙醇溶液提取物表现出最高的总酚(219.01 mg GAE/g)、总黄酮含量(7.23 mg CE/g)及最强的DPPH自由基清除能力(35.46 mg TE/g)和还原能力(1.89 mmol Fe SO_4/g);总酚、总黄酮含量与DPPH自由基清除能力、还原能力之间呈正相关,与总抗氧化能力呈显著负相关,表明多酚类物质是青钱柳中主要的抗氧化剂。UPLC-QTOF-MS/MS分析70%乙醇溶液提取物并初步鉴定出22种化合物,包括2种有机酸、4种酚酸、5种黄酮、8种三萜皂苷类和3种酯类,其中酚酸和黄酮类化合物是主要的抗氧化活性成分,有机酸、三萜皂苷及酯类化合物可能是潜在的抗氧化活性成分。     

Liaison of phenolic acids and biological activity of escalating cultivars of Daucus carota

The objective of the present study was to analyze and compare the phenolic compounds and their antioxidant capacities of new lines of Dacus carota. The selected cultivars showed high variation in the contents of total phenolics (30.26–65.39 mg/100 g FW) and total ascorbic acid (41.12–58.36 mg/100 g FW). Analysis on RP-HPLC revealed that hydroxycinnamic acids and its derivatives were major phenolic compounds present in D. carota extracts, whereas 5-caffeolquinic acid was a major hydroxycinnamic acid (ranged from 30.26 to 65.39 mg/100 g FW). DCP cultivar showed high total antioxidant capacity (77.69 mg/100 g), 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging capacity (52.36 mg/100 g), superoxide radical scavenging capacity (53.69 mg/100 g), and hydroxyl radical scavenging capacity (51.91 mg/100 g). A linear relationship was found between total phenolic acid contents and antioxidant capacity. Both phenolic compounds and antioxidant capacities varied significantly (ρ < 0.05) among cultivars. DCP cultivar was found to be a rich source of phenolics and ascorbic acid with high antioxidant activity.     

3 种梨果实发育过程中酚类物质及其抗氧化能力分析

为进一步了解新疆主要栽培品种梨生长发育期果实酚类物质和抗氧化能力的变化规律,选取‘库尔勒香梨’‘早酥梨’及其杂交后代‘新梨7号’果实为试材,对其总酚、总黄酮、酚类物质含量以及1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基清除能力和2,2’-联氮-双-3-乙基苯并噻唑啉-6-磺酸（2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid),ABTS）阳离子自由基清除能力进行分析。结果表明：3 种梨果实总酚含量、总黄酮含量、DPPH自由基清除能力在整个生长发育过程中总体呈逐渐降低的变化趋势,ABTS阳离子自由基清除能力呈先降低后升高再降低的变化趋势,花后50 d‘早酥梨’果实中总酚和总黄酮含量、DPPH自由基清除能力最高,分别达23.10、32.25 mg/g和29.12 μmol/g;花后80 d,‘早酥梨’果实ABTS阳离子自由基清除能力最高,达80.74 μmol/g。不同生长发育期同品种梨果实的酚类物质含量均存在明显差异,果实中的熊果苷、儿茶素、绿原酸、表儿茶素、槲皮葡萄糖苷、山柰酚-3-O-葡萄糖苷含量总体逐渐降低,其中熊果苷含量最高,平均值为5 797.82 μg/g,其次是绿原酸含量,平均值为1 781.02 μg/g。梨果实中总黄酮、总酚、熊果苷、儿茶素、绿原酸、表儿茶素含量与DPPH自由基清除能力呈极显著正相关（P＜0.01）。3 种梨幼果期（花后50 d）酚类物质及抗氧化能力较高,‘早酥梨’总酚含量、总黄酮含量、DPPH自由基清除能力和ABTS阳离子自由基清除能力均比‘库尔勒香梨’和‘新梨7号’高。     

干制方式对红枣多酚抗氧化活性的影响

研究自然干制和热风干制对红枣中的酚类化合物及其抗氧化活性的影响。测定红枣干制前后其总酚含量、总黄酮含量、原花青素含量、DPPH自由基清除能力及总抗氧化能力的变化。结果表明：红枣经干制后酚类化合物含量显著下降,总黄酮含量变化不明显,但经热风干制后其原花青素含量显著升高。红枣的总抗氧化活性与总黄酮和原花青素含量相关性较小,而与酚类化合物相关性较大。经热风干制和自然干制的红枣总抗氧化活性间无显著性差异,但热风干制所需时间短,制得的红枣香味浓,因此建议采用热风干制法干制红枣。     

Exploring the effect of microwave treatment on phenolic flavonoids,antioxidant capacity,and phenolic in vitro bioaccessibility of sorghum

The effect of microwave treatment on phenolics, flavonoids, antioxidant capacity, and phenolic in vitro bioaccessibility of white and red sorghum was evaluated. After microwave treatment for 40 s, the contents of free, bound, and total phenolics in white and red sorghum increased by 15.6–42.6, 4.0–23.4, and 19.7–66.0 mg gallic acid equivalents 100 g⁻¹ dry weight (DW), respectively, and the contents of free, bound, and total flavonoids increased by 9.4–11.2, 4.8–5.4, and 14.2–16.6 mg rutin equivalents 100 g⁻¹ DW, respectively. With increasing microwave treatment time, the contents of phenolic acids and flavonoids in white and red sorghum first increased and then decreased. Additionally, the changes in antioxidant capacity indicated a similar trend with phenolic contents for white and red sorghum. In vitro gastrointestinal digestion indicated that microwave treatment had no effect on the phenolic bioaccessibility of white and red sorghum but increased the release amount of phenolic acid and antioxidant capacity.     

Proximate,mineral, amino acid composition,phenolic profile,antioxidant and functional properties of oilseed cakes

Proximate, minerals, amino acids (AAs), phenolic composition, antioxidant and functional properties of flaxseed (FSC), sesame (SSC), mustard (MSC), nigella (NSC) and groundnut (GSC) seedcakes were studied. SSC exhibited higher ash and fat contents while GSC and FSC had more protein and mineral contents (P, Mg, Mn and Cu), respectively. The total flavonoids, phenolics and antioxidant activity were higher in NSC (18.60 mg QE g⁻¹), MSC (5.12 mg GAE g⁻¹) and FSC (12.28 µmol TE g⁻¹), respectively. NSC exhibited the highest oil absorption capacity (2.10 g g⁻¹) and emulsifying activity index (89.52 m² g⁻¹). Twenty-one AAs including citrulline and ɣ-aminobutyric acid were detected in oilseed cakes (OSC). MSC had more essential AAs (methionine, isoleucine, tryptophan, threonine and lysine) while GSC had more total hydrophobic, acidic and basic AAs. Syringic acid and rutin were identified as major phenolic compounds in GSC and MSC, respectively. The total free phenolic acids were more in GSC while FSC had high total bound phenolic acids and flavonoids. OSC can be utilised in food products as a supplement to improve nutritional properties.     

Phenolic composition and antioxidant capacities of ten Algerian date (Phoenix dactylifera L.) cultivars: A comparative study

Phenolic compounds and antioxidant capacities of ten Algerian date (Phoenix dactylifera L.) cultivars were investigated. The total phenolic, flavonoid, flavonol and condensed tannin contents of the different cultivars were measured using colorimetric methods. Free phenolic acid and flavonoid profiles of the date cultivars were analyzed by high performance liquid chromatography with diode array detection (HPLC-DAD), while antioxidant capacities were evaluated in vitro using scavenging assays of 1,1-diphenyl-2-picrylhydrazyl radical and hydrogen peroxide, ferric reducing power, and ferrous ion chelating ability. The results showed that the cultivars exerted different antioxidant capacities, and had different phenolic acid and flavonoid patterns. Among the tested cultivars, Ghazi, Arechti and Sebt Mira possessed the strongest antioxidant capacities and the highest phenolic contents. Four phenolic acids (gallic, ferulic, coumaric and caffeic acids) and five flavonoids (isoquercetrin, quercetrin, rutin, quercetin and luteolin) were identified and quantified.     

Major Phytochemical Composition of 3 Native Korean Citrus Varieties and Bioactive Activity on V79-4 Cells Induced by Oxidative Stress

ABSTRACT:  Three citrus varieties grown in Korea, namely, Yuza ( Citrus junos  Sieb ex Tanaka), Kjool ( Citrus unshiu  Marcow), and Dangyooja ( Citrus grandis  Osbeck), were evaluated for their dietary fiber, total phenolics, total flavonoids, and total carotenoids as well as individual flavonoids composition. The biochemical characteristics of citrus varieties were examined by the antioxidant capacity (731 to 1221 μmol of Trolox equivalent/g), total phenolic (334 to 411 mg of chlorogenic acid equivalent/100 g), total flavonoid contents (214 to 281 mg of catechin equivalent/100 g), and total carotenoid contents (63 to 84 mg/100 g). Six flavonoids, including naringin, naringenin, hesperidin, hesperetin, neohesperidin, and luteolin, were tentatively identified. Naringin, hesperidin, and neohesperidin were the predominant flavonoids in 3 citrus varieties. Among the citrus varieties studied, Yuza showed higher antioxidant activity, total phenolics, total carotenoids, and lower superoxide radical scavenging assay (SRSA) IC₅₀ values than other varieties. Furthermore, Korean citrus showed higher protective effect on gap-junction intercellular communication (GJIC) as compared to vitamin C and luteolin.     

梅花果实品质及抑菌、抗氧化活性分析

为揭示不同品种梅花果实的品质及抑菌、抗氧化活性差异,从抗寒梅花中筛选果实品质优良的品种,为抗寒花果兼用梅的选育以及梅花果实综合利用提供依据。对8 个品种梅花果实的品质（外观品质和食用品质）性状、抑菌和抗氧化活性进行评价,利用高效液相色谱-质谱联用技术对酚类化合物进行分离和检测,对果实品质性状与抑菌和抗氧化活性进行相关性分析。结果表明：不同品种梅花果实的品质性状差异显著,‘淡丰后’、‘粉靥丰后’、‘武藏野’和‘飞绿萼’等级评价较高;‘丰后’、‘武藏野’、‘飞绿萼’总酚和总黄酮含量较高,从3 个品种中都分离出儿茶素、迷迭香酸、圣草酚、丁香酸、芦丁5 种酚类化合物,梅花果实的抑菌和抗氧化活性与总酚和总黄酮含量存在相关关系。‘武藏野’和‘飞绿萼’是优良的抗寒花果兼用梅,果实品质性状较优,可以作为天然抗氧化剂或功能性食品进行开发利用。     

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.     

5 种梅干菜的酚类化合物及抗氧化能力比较分析

以市售5 种梅干菜为研究对象,测定梅干菜酚类化合物的含量,用高效液相色谱-串联质谱（high performance liquid chromatography-tandem mass spectrometry,HPLC-MS/MS）法鉴定梅干菜酚类化合物的种类,并用4 种抗氧化能力评价方法评价梅干菜。结果表明,市售5?种梅干菜所含的酚类化合物含量和各酚类化合物所占的比例及其抗氧化能力差异显著。其中咕咕鲜牌梅干菜（GGX）的总酚含量为14.18?mg?GAE/g,总黄酮含量为7.10?mg?RE/g,2,2’-联氮-双-（3-乙基苯并噻唑啉-6-磺酸）二铵盐（2,2’-azino-bis(3-ethylbenzthiazoline-6-sulphonate),ABTS）法、铁离子还原（ferric reducing antioxidant power,FRAP）法、1,1-二苯基-2-三硝基苯肼法和氧自由基吸收能力（oxygen radical absorbance capacity,ORAC）法测得的抗氧化能力分别为28.09、32.88、31.72?μmol?TE/g和445.55?μmol?TE/g,显著高于其他4?种梅干菜。其次,利用HPLC-MS/MS法分析鉴定出梅干菜中共含有17?种酚类化合物,包括9?种类黄酮和8?种酚酸。其中,梅干菜中的类黄酮主要有野漆树苷、山柰酚、异鼠李素、柚皮素等;酚酸主要有阿魏酸、香豆酸和肉桂酸等。此外,4?种抗氧化能力评价方法中,ABTS与FRAP相关性最高,相关系数为0.967;ORAC法测得的梅干菜抗氧化能力显著高于其他3?种方法;而ABTS法与梅干菜的抗氧化剂相关性最高,最适合评价梅干菜的总抗氧化能力。综上所述,不同种类市售梅干菜的酚类化合物含量和抗氧化能力均不同,其中,GGX总酚含量最高、抗氧化能力最强。     

重庆地方名柚果肉酚类物质含量及其抗氧化活性分析

通过紫外分光光度计法和高效液相色谱法分别测定10 种重庆地方名柚成熟果实囊衣、汁胞2 个部位的总酚、总黄酮含量及类黄酮、酚酸组分和含量,并采用1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）、铁离子还原能力（ferric reducing antioxidant power,FRAP）测定、2,2’-联氮-双-（3-乙基苯并噻唑啉-6-磺酸）二铵盐（2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate),ABTS）3 种方法对其抗氧化活性进行评价。结果表明：囊衣的总黄酮含量和类黄酮含量较高,‘琯溪蜜柚’总黄酮含量最高达10.97 mg/g,类黄酮中地奥司明含量最高,均值为1 000.72 μg/g,其含量最高为‘五布柚’,达到2 366.77 μg/g;汁胞的总酚含量和酚酸含量较高,‘真龙柚3号’总酚含量最高达8.84 mg/g,酚酸中没食子酸含量最高,均值为1 040.16 μg/g,其含量最高为‘长寿沙田柚’,达到1 325.89 μg/g。利用DPPH法和FRAP法测定2 个部位抗氧化活性,汁胞高于囊衣,ABTS法则囊衣高于汁胞。综合抗氧化能力指数表明,‘琯溪蜜柚’囊衣、‘梁平柚78-8’汁胞的抗氧化活性最强。通过本研究,不仅能够了解重庆地方名柚果实囊衣、汁胞部位酚类物质组分和含量,同时为柑橘酚类物质的应用选择提供了一定的理论依据,促进了柑橘果品营养学的发展。     

木贼醇提物不同萃取部位总酚酸、黄酮含量测定及抗氧化活性研究

目的:对木贼的乙醇提取物不同萃取部位进行总酚酸、黄酮含量测定及抗氧化活性比较,以探知木贼抗氧化活性物质基础。方法:木贼经70%乙醇超声提取浓缩后,采用有机溶剂萃取法依次得到石油醚、乙酸乙酯、正丁醇、水相4个部位萃取物;利用紫外-分光光度法比较各萃取部位总黄酮、酚酸含量差异;以抗坏血酸为阳性对照,比较不同萃取部位还原能力、羟自由基(·OH)、1,1-二苯基-2-三硝基苯肼(DPPH·)、2,2'-联氮-双(3-乙基苯并噻唑-6-磺酸)二铵盐(ABTS+·)清除率的差异,评价各部位抗氧化能力强弱。结果:木贼各萃取物总黄酮含量在5.70~61.55 mg/g 范围内,总酚酸含量在4.07~19.10 mg/g 范围内,乙酸乙酯萃取物总黄酮与酚酸含量明显高于其他萃取物,其还原能力、羟自由基、DPPH·、ABTS+·清除率也明显高于正丁醇、石油醚和水相萃取物,乙酸乙酯萃取物对羟自由基、ABTS+·、DPPH·清除能力IC₅₀值分别为:(0.321±0.0026)、(0.213±0.0010)和(0.169±0.0014) mg/mL。结论:经各相溶剂萃取后木贼有效成分得到初步分离,乙酸乙酯相萃取部位总黄酮和酚酸相对含量及抗氧化活性明显强于总提物和其他萃取部位,且其抗氧化能力呈量效关系。实验发现木贼中黄酮和酚酸类成分与其抗氧化能力密切相关。     

Varietal differences among the phenolic profiles and antioxidant properties of four cultivars of spine grape (Vitis davidii Foex) in Chongyi County (China)

Spine grape (Vitis davidii Foex) is an important wild plant species in South China. To provide sufficient experimental evidence for the strong antioxidant activity of spine grapes, four cultivars from Chongyi County, China, including three red varieties (Junzi #1, Junzi #2, and Liantang) and one white variety (Baiyu) were evaluated. The Junzi #1 had the highest phenolic content (total phenolic, flavonoids, flavanols, and anthocyanins) and the strongest antioxidant capacity (DPPH radical-scavenging capacity, cupric-reducing capacity and hydroxyl radical-scavenging activity) among the four varieties. HPLC analysis of spine grapes revealed that the (+)-catechin was the most abundant phenolics and the hydroxycinnamic acids were the major phenolic acids in the four varieties. Hierarchical cluster analysis showed that the Junzi #1 belongs to the group with high phenolic content and strong antioxidant power. The results suggest the Junzi #1 has the best health promoting properties, and the higher utilization value and potential for development.     

Phenolic profiles and antioxidant activity of litchi pulp of different cultivars cultivated in Southern China

The phenolic profiles and antioxidant activity of litchi pulp of 13 varieties were investigated. The free, bound and total phenolic contents were 66.17–226.03, 11.18–40.54, and 101.51–259.18 mg of gallic acid equivalents/100 g, respectively. The free, bound and total flavonoid contents were 16.68–110.33, 10.48–22.75, and 39.43–129.86 mg of catechin equivalents/100 g, respectively. Free phenolics and flavonoids contributed averagely 80.1% and 75% to their total contents, respectively. Six individual phenolics (gallic acid, chlorogenic acid, (+)-catechin, caffeic acid, (?)-epicatechin, and rutin) were detected in litchi pulp by HPLC. The contents of each compound in free and bound fractions were determined. Significant varietal discrepancy in antioxidant activity was also found by FRAP and DPPH scavenging capacity methods. Antioxidant activity was significantly correlated with phenolic and flavonoid contents. Thus, phenolics and flavonoids exist mainly in the free form in litchi pulp. There were significant varietal differences in phytochemical contents and antioxidant activity of litchi pulp.     

Phenolic acid content and composition in leaves and roots of common commercial sweetpotato (Ipomea batatas L.) cultivars in the United States

ABSTRACT:  Phenolic acids in commercially important sweet potato cultivars grown in the United States were analyzed using reversed-phase high-performance liquid chromatography (HPLC). Caffeic acid, chlorogenic acid, 4,5-di-O-caffeoylquinic acid, 3,5-di-O-caffeoylquinic acid, and 3,4-di-O-caffeoylquinic acid were well separated with an isocratic elution in less than 25 min compared to about 120 min for analyzing and re-equilibrating the column with a gradient method. The isocratic elution order of these caffeoylquinic acid derivatives was confirmed by LC-MS/MS. Chlorogenic acid was the highest in root tissues, while 3,5-di-O-caffeoylquinic acid and/or 4,5-di-O-caffeoylquinic acid were predominant in the leaves. Steam cooking resulted in statistically nonsignificant increases in the concentration of total phenolics and all the individual phenolic acids identified. Sweetpotato leaves had the highest phenolic acid content followed by the peel, whole root, and flesh tissues. However, there was no significant difference in the total phenolic content and antioxidant activity between purees made from the whole and peeled sweet potatoes.     

低温真空膨化与自然干制对红枣抗氧化活性的影响

目的：研究低温真空膨化和自然干制对红枣抗氧化成分及活性的影响,为生产加工优质枣产品和低温真空膨化技术在红枣加工方面应用提供科学依据。方法：以矮化密植枣树所得枣果为材料,采用Folin-Ciocalteu与NaNO2-Al(NO3)3法测定总酚、总黄酮含量;通过DPPH自由基清除率、ABTS+•清除能力、总还原力和抗亚油酸过氧化能力等指标表征枣果抗氧化能力;采用高效液相色谱法对酚类化合物进行定性定量分析。结果：红枣经膨化后总酚含量显著增加,而总黄酮未发生明显变化,自然干制使总酚、总黄酮含量显著降低。膨化枣DPPH自由基清除能力和总还原力显著优于鲜枣和自然干制枣,自然干制处理使红枣ABTS+•清除能力和β-胡萝卜-亚油酸抗氧化活性显著低于膨化枣与鲜枣。膨化枣中总酚、总黄酮和抗氧化能力显著高于自然干制枣。干制处理使枣果中酚类化合物组成发生明显变化,膨化枣中没食子酸、对羟基苯甲酸、咖啡酸、对香豆酸、阿魏酸、芦丁、肉桂酸和槲皮素的含量最高。相关性研究表明鲜枣与干制枣中抗氧化活性与总酚、总黄酮显著相关。结论：低温真空膨化枣含有丰富的酚类化合物与最高抗氧化能力,且加工时间短,口感酥脆香甜。综上所述,低温真空膨化技术可作为一种可用于规模化干制枣的现代化加工技术。