桃果实细胞内糖酸分布对果实甜酸风味的影响

以成熟‘白凤’桃果实为实验材料,采用区室化分析方法计算细胞内液泡、细胞质和细胞间隙中各糖酸组分的含量,并用调查问卷的方式对成熟桃果实甜酸风味进行评价打分,研究果肉细胞内各糖酸组分含量及其分布对果实甜酸风味的影响。结果表明:(1)成熟桃果实中可溶性糖(蔗糖、葡萄糖、果糖和山梨醇)在液泡、细胞质和细胞间隙的含量分别为27.3、11.6和9.0mg·g-1,有机酸(苹果酸、柠檬酸、奎宁酸和莽草酸)含量分别为2.09、0.94和0.35mg·g-1;蔗糖和苹果酸含量分别占果实可溶性糖和有机酸含量的80.6%和77.0%,是成熟桃果实中糖和酸的主要储存形式。(2)果实细胞内各糖酸组分通过细胞膜的渗透速率明显高于液泡膜。(3)块状处理桃果实液泡、细胞质与细胞间隙中的糖含量比、酸含量比及糖酸比分别为3.0∶1.3∶1.0、6.0∶2.7∶1.0、13.9∶12.4∶23.1,而匀浆处理果实的细胞结构被破坏,其不同细胞器中的比例分别为1.0∶1.0∶1.0、1.0∶1.0∶1.0、14.0∶14.0∶14.0;块状果实风味评价得分(2.99)明显高于匀浆处理果实(1.98)。研究认为,桃果实细胞中液泡、细胞质和细胞间隙之间糖酸含量以及糖酸比的差异可能是导致果实甜度风味变化的重要原因。     

八个贵州地方桃品种果实甜酸风味品质分析

为了评价贵州地方桃品种果实的甜酸风味品质,以主栽桃品种‘燕红’作对照,采用高效液相色谱法测定了贵州8个地方桃品种的果肉糖酸组分及含量。结果表明:(1)8个地方桃品种果肉中糖主要由蔗糖、葡萄糖、果糖和山梨醇组成,其中蔗糖的平均含量最高(55.62 mg/g),约占总糖的71.30%,但变异系数仅为17.92%;8个地方桃品种中,‘米桃’的葡萄糖与果糖含量差异较大,其果糖/葡萄糖的比值为1.21,而其它7个品种的葡萄糖与果糖含量相近。(2)8个地方桃品种果肉中有机酸主要由苹果酸、柠檬酸、奎宁酸和莽草酸组成,其中苹果酸含量最高,约占总酸的60.61%,但在‘白花桃’果实中有机酸含量以奎宁酸为主。(3)对8个地方桃品种果实的糖酸组分进行主成分分析发现,苹果酸含量和山梨醇含量的载荷系数分别为0.910和0.897,说明它们是影响果实甜酸风味的主导因素,且对改善果实的甜酸风味品质具有重要作用。8个贵州地方桃果实的甜酸风味分别为:‘黄腊桃’为甜,‘血桃’、‘青桃’、‘镇远桃’、‘红枫桃’为酸甜,‘白花桃’、‘西桃’和‘米桃’为酸。     

桃果实成熟前后细胞壁成分和降解酶活性的变化及其与果实硬度的关系

比较桃品种‘双久红’和‘川中岛白桃’果实成熟前后20 d内果肉硬度、细胞壁成分和细胞壁降解酶活性变化的结果表明,桃果实成熟5 d后,‘双久红’桃果实的硬度、纤维素含量和原果胶含量均极显著高于‘川中岛白桃’:从成熟前15 d开始,‘双久红’的水溶性果胶含量、多聚半乳糖醛酸酶活性和纤维素酶活性均极显著低于‘川中岛白桃’;整个成熟期间,‘双久红’的果胶甲酯酶活性明显低于‘川中岛白桃’。相关分析表明,果实硬度与原果胶、纤维素含量呈极显著正相关,而与可溶性果胶含量、多聚半乳糖醛酸酶活性和纤维素酶活性呈极显著负相关。     

桃新品系“保佳俊”果实发育后期主要营养成分的动态变化

‘保佳俊’为河北农业大学选育的新品系,其果实综合性状优良,耐贮运性强。为更全面的了解该品系在果实成熟后期的营养成分的动态变化,本试验以‘保佳俊’和‘大久保’为试材,对桃果实发育后期的生理生化指标进行测定,结果表明:在果实发育后期,‘保佳俊’和‘大久保’的单果重及横、纵、侧径变化趋势一致,均随着果实的成熟,呈上升的趋势;糖分含量呈上升的趋势,可滴定酸含量呈下降趋势。‘保佳俊’的果实硬度、糖分含量及可溶性蛋白含量均高于‘大久保’,可滴定酸含量低于‘大久保’,其风味、品质及耐贮运性都优于‘大久保’。     

果梅果实发育过程中有机酸含量及相关代谢酶活性的变化特征

以优选荔波野生梅单株‘荔波-3’和‘荔波-11’为试验材料,采用高效液相色谱法(HPLC)测定了果梅果实在发育过程中有机酸含量及相关代谢酶活性变化特征。结果表明:(1)‘荔波-3’和‘荔波-11’果梅果实中柠檬酸和苹果酸主要在果实发育后期积累,花后140d两品种的柠檬酸积累量达到最大,且果实中总酸的积累量也相应的达到最大值。(2)柠檬酸积累量与柠檬酸合成酶(CS)活性呈极显著正相关关系,‘荔波-11’因CS活性高于‘荔波-3’,使得其果实成熟时的柠檬酸含量高于后者。(3)苹果酸积累量与磷酸烯醇式丙酮酸羧化酶(PEPC)和NAD-苹果酸脱氢酶(NAD-MDH)活性呈极显著正相关关系,但与NADP-苹果酸酶(NADP-ME)活性呈负相关关系;在花后45~100d内,果梅果实中PEPC和NAD-MDH活性迅速升高,而NADP-ME活性相对较低,使苹果酸积累量迅速增加;在花后120~140d,‘荔波-3’果实中PEPC、NADP-MDH活性显著高于‘荔波-11’,而其NADP-ME活性低于‘荔波-11’,导致成熟时‘荔波-11’的苹果酸含量高于‘荔波-3’。可见,果梅果实的有机酸主要在果实发育后期积累,有机酸积累差异受多个酶协同调控;苹果酸的积累差异主要由NAD-MDH、PEPC和NADP-ME活性协同变化引起,柠檬酸积累差异主要受CS活性变化影响。     

苹果新品种‘瑞阳’果实主要特性研究

该研究以红色晚熟苹果新品种‘瑞阳’及其母本‘秦冠’、父本‘富士’为试验材料,分析各品种果实发育过程中的生长动态、色泽变化以及采收期对其果实品质的影响,为品种栽培管理和推广应用提供参考。结果表明:(1)在果实生长发育期,‘瑞阳’单果质量的变化与双亲接近,单果质量的日增长高峰出现在花后105d,果实发育前期纵径增长较大,果形指数大,在发育后期果形指数降低,至成熟时果形指数达到0.86,介于父母本‘秦冠’和‘富士’之间。(2)套袋处理使果实着色期的色泽参数a*值和花青苷含量上升,但品种间存在差异,套袋处理对‘瑞阳’的色泽参数a*值和花青苷含量影响不大。(3)随果实采后天数的延长,各采收期‘瑞阳’果实淀粉指数逐渐上升,硬度和可滴定酸逐渐下降,而可溶性固形物含量先上升后下降;‘瑞阳’果实在花后174d采收时,果实的硬度和可滴定酸下降均较少,且果实可溶性固形物含量保持在较高水平,能较好地维持该品种的果实品质。研究发现,‘瑞阳’苹果果实膨大期出现在花后105d前后,果实套袋对其表面色泽和花青苷含量影响不大,在陕西渭北以花后174d前后采收为宜。     

桃果实发育阶段肉色形成与类胡萝卜素的变化分析

为了分析不同肉色类型桃果实发育过程中类胡萝卜素成分的变化特点及其颜色差异形成的因素,选择‘半斤桃’(红肉)、‘图八德’(黄肉)、‘正姬’(白肉)桃品种为试材,采用紫外分光光度计和高效液相色谱法(HPLC)对桃果实类胡萝卜素及其组分含量进行定性定量分析.结果显示:(1)桃果实的主要类胡萝卜素成分为叶黄素、玉米黄素、β-隐黄质、α-胡萝卜素和β-胡萝卜素.(2)随着果实的发育,‘半斤桃’和‘正姬’的类胡萝卜素总含量逐渐降低,而‘图八德’则是先降低后上升,且明显高于前二者;3种类型桃果实的叶黄素均逐渐降低,果实成熟时接近0;玉米黄素呈先降后升的趋势,果实成熟时达到最大值;‘半斤桃’和‘正姬’的β-隐黄质、α-胡萝卜素和β-胡萝卜素呈逐渐下降的趋势,而‘图八德’的β-隐黄质含量先升后微降最后上升、α-胡萝卜素和p-胡萝卜素含量则逐渐增加,且均在果实成熟时达到最大值.(3)‘图八德’成熟果实中的类胡萝卜素总含量达到最大值,其中β-胡萝卜素含量最高,占5个成分之和的75.99％.研究表明,桃果实肉色形成与类胡萝卜素的含量与成分有着紧密的联系,尤其是其中的β-胡萝卜素含量.     

增施钾肥对大棚蟠桃品质及营养生长的影响

该研究以蟠桃品种‘金霞蟠桃’和‘玉霞蟠桃’为试材,分别在2个品种成熟前3周(3W)、2周(2W)和1周(1W)每树环施钾肥(K2O)1 000g,比较不同时期施肥处理蟠桃果实外观品质、内在品质以及营养生长的变化。结果表明:(1)在蟠桃果实成熟前2W和3W尤其是2W施用钾肥,蟠桃果实单果重和体积总体较大,‘金霞蟠桃’2W处理果实单果重、横径和侧径分别显著高于1W处理11.48%、3.51%和3.03%,‘玉霞蟠桃’2W处理则分别显著高于1W处理56.86%、14.97%和3.67%;(2)不同时期增施钾肥对‘玉霞蟠桃’果实颜色的变化影响总体较小,‘金霞蟠桃’2W和3W处理果实的a*值分别显著高于1W处理55.02%和44.49%,但2W和3W处理之间差异不显著;(3)增施钾肥后,2个蟠桃品种果实可溶性固形物含量、蔗糖含量从高到低依次为2W3W1W,可溶性糖总量大小也依次为2W3W1W,但2W和3W处理间差异不显著;不同时期增施钾肥对2个蟠桃品种果实有机酸总量和枝叶营养生长总体影响不大。研究认为,在蟠桃果实成熟前2周左右施用钾肥,成熟时果实体积、单果重增大,果肉可溶性固形物、蔗糖、可溶性总糖含量以及糖酸比高,果实综合品质得到有效改善,但增施钾肥过早或过晚都无法达到最佳效果。     

不同产地‘金圆’猕猴桃低温贮藏下的生理指标及贮藏性变化

以中华猕猴桃(Actinidia chinensis Planch.)黄肉新品种‘金圆’果实为材料,通过低温贮藏实验(1℃±0.5℃,相对湿度90%~95%),系统研究武汉和六盘水所产‘金圆’果实的生理指标及贮藏性。结果显示,两地‘金圆’果实硬度和色彩角(h值)随贮藏时间延长而逐渐下降,硬度在前20 d下降幅度大。果实可溶性固形物(SSC)含量和干物质在贮藏期间变化规律基本一致,六盘水产果实的SSC和干物质含量高于武汉。武汉产果实VC、可溶性总糖、可滴定酸含量仅在80 d时高于六盘水,其他时间均低于六盘水。两地果实的固酸比和糖酸比变化一致,六盘水产果实固酸比(SSC/TA)和糖酸比(SS/TA)在80 d时均达到峰值,而武汉产果实只有糖酸比达到峰值。随贮藏时间延长,两地果实的失重率均缓慢上升,160 d时武汉和六盘水果实的失重率分别为2.82%和2.55%;在贮藏前60 d两地果实腐烂率较低,之后上升较快,160 d时六盘水产果实腐烂率是武汉的1.77倍。本研究结果表明六盘水产‘金圆’果实的风味品质优于武汉,而武汉产果实贮藏性更好些。     

橄榄果实发育成熟过程中糖积累与相关酶活性的关系

以可溶性总糖含量差异明显的2个橄榄品种为试验材料,测定果实发育成熟过程中蔗糖、葡萄糖、果糖、可溶性总糖含量及蔗糖代谢相关酶活性的动态变化,并对果实糖积累与酶活性进行相关性分析,以明确不同橄榄品种果实糖积累差异的生理基础,为进一步在代谢与分子水平探讨橄榄果实糖积累机制提供依据。结果表明:(1)蔗糖快速积累期是橄榄品种间果实蔗糖积累差异的关键时期,并影响成熟时果实可溶性总糖含量的高低,其中‘马坑22’蔗糖快速积累期较长,增长幅度较大,成熟时可溶性糖含量高;成熟时‘马坑22’、‘檀头23’果实内己糖与蔗糖比分别为0.668、0.904。(2)在蔗糖快速积累期内,‘马坑22’酸性转化酶(AI)活性低于‘檀头23’,为其蔗糖积累创造条件,而中性转化酶活性高于后者则有利于其增加果实库强;两品种蔗糖磷酸合成酶(SPS)活性变化差异不大,说明SPS不是蔗糖积累的关键酶;‘马坑22’蔗糖合成酶(SuSy)合成方向活性在花后144~186d增幅显著高于‘檀头23’,说明SuSy为果实蔗糖积累的关键酶。(3)‘马坑22’蔗糖快速积累主要依靠SuSy合成方向活性变化促进蔗糖合成,‘檀头23’蔗糖快速积累主要依靠SuSy分解方向活性变化促进蔗糖直接进入果实。     

Isolation of Vacuoles from Immature Apple Fruit Flesh and Compartmentation of Sugars, Organic Acids, Phenolic Compounds and Amino Acids

Vacuoles of immature apple fruit (Malus pumila Mill. var. domesticaSchneid.) were obtained by purification using Ficoll densitygradient centrifugation after lysis of the protoplasts by bothmild osmotic shock and the addition of EDTA and BSA. The recoverywas about 35% of the protoplasts. The isolated vacuoles hada mean diameter of about 100 µm. The distribution of sugars, organic acids, phenolic compoundsand amino acids in the vacuole, the cytoplasm and the free spacewas determined. Almost all of the fructose and glucose, themajor sugars of the tissue, were found in the vacuole. Sorbitolwas mainly located in the free space and the vacuole, and sucrosein the free space and the cytoplasm. More than 90% of the malicacid, the main organic acid, was located in the vacuole. Almostall of the phenolic compounds were also deposited in the vacuole. The volumes of the vacuole, the cytoplasm and the free spacein the whole tissue were calculated from the cell numbers ofthe whole tissue, the volume of the isolated protoplasts, andthe volume of the vacuoles present in the protoplast. The soluteconcentration in each compartment was estimated: vacuoles, 888mM; cytoplasm, 37 mM; free space, 57 mM. How these compartmentationsof solutes affected the translocation of sugars into the fruitand the cell expansion is discussed. ¹This paper is contribution A-159 of the Fruit Tree ResearchStation. (Received July 7, 1983; Accepted November 14, 1983)     

Neoculin, a taste-modifying sweet protein, accumulates in ripening fruits of cultivated Curculigo latifolia

Neoculin is a sweet protein with a taste-modifying activity of converting sourness to sweetness. It occurs in the fruits of Curculigo latifolia, a wild plant found in tropical Asia. We successfully cultivated the plant and evaluated the production of neoculin. The neoculin content of the fruit was high for 10 weeks after flowering, following which the yield decreased gradually. The optimal period for harvesting the fruits with sensory activity coincided with this 10-week peak period during which the amount of neoculin was 1-3mg in the whole fruit and 1.3mg/g of pulp. Immunohistochemical staining showed that neoculin occurred in the whole fruit, especially at the basal portion. Although it is known that neoculin comprises an acidic subunit (NAS) with an N-glycosylated moiety and a basic subunit (NBS), protein gel blot analysis revealed the presence of a non-glycosylated NAS species. This suggests the presence of multiple NAS-NBS heterodimers in our cultivar.     

Distribution of Sorbitol, Neutral Sugars, Free Amino Acids, Malic Acid and Some Hydrolytic Enzymes in Vacuoles of Apple Cotyledons

Vacuoles of apple cotyledons (Malus pumila Mill. var. domesticaSchneid.) were obtained by purification with Ficoll densitygradient centrifugation after the protoplasts were lysed byboth osmotic shock and the addition of EDTA. High levels ofacid protease and carboxypeptidase activity were detected inthe vacuoles along with acid phosphatase, phosphodiesteraseand ATPase. The distribution of sorbitol and other sugars inthe vacuoles, the protoplast and extracellular free space wasdetermined. About 45, 60 and 90% of the sorbitol, glucose andsucrose, respectively, contained in whole tissue were foundin the extracellular free space, and 54% of the sorbitol inthe protoplast was detected in the vacuole. The sorbitol inthe vacuoles and the extravacuole of the protoplast was about80 and 70%, respectively, of the total sugar content of thecell. Arginine was the most abundant free amino acid in theprotoplast, and about 90% of it was contained in the vacuole.More than 80% of the total amino acids and 50% of the proteinwere also located in the vacuole, as well as most of the malate.The amounts of the total sugars, total amino acids, proteinand malate in the vacuoles were to 250, 400, 48 and 9 µg/10⁶cells, respectively. The results suggest that the vacuoles ofapple cotyledons contain a large pool of amino acids and proteinsrather than sugars, and have a close connection with proteinbody degradation. ¹ This paper is contribution A-l37 of the Fruit Tree ResearchStation. (Received January 20, 1982; Accepted May 18, 1982)     

Contents of Sugars, Fruit Acids, Amino Acids and Phenolic Compounds of Apple Fruits i n Relation to their Susceptibility to Botryosphaeria ribis

Five apple cultivars showing different levels of susceptibility to Botryosphaeria ribis were used to study the relationship between susceptibility and contents of sugars, fruit acids, amino acids and phenolic compounds in the fruits at various stages of maturity. Immature fruits of all the cultivars tested were completely resistant until 10 July. The fungus grew better on the yellow-coloured cultivars than the red-coloured cultivars. The low amount of reducing sugars and also the high levels of fruit acids, amino acids and total phenols were found in immature apple fruits, irrespective of cultivar. No consistent differences between the cultivars were recognized with regard to the contents of soluble sugars, fruit acids and phenols in fruit flesh during the maturity of fruits. However, only the levels of total soluble amino acids in fruit flesh and of total phenols in fruit peel at late stage of maturity consistently varied between the cultivars. The dark red-coloured, resistant cultivars Miller spur and Starkrimson showed higher contents of amino acids and phenols in fruit tissues than did the yellow-coloured, susceptible cultivars.     

Hexane soluble non-volatiles in flowering to fruiting stages of Fatsia japonica

The n-hexane soluble non-volatile fraction of the acetone extracts from the flower buds, the flowers and the immature and the mature fruits of Fatsia japonica were all found to contain fatty acids, fatty acid methyl esters, squalene, β-amyrin and sterols. At all the stages between budding to the mature fruit, the major fatty acids were palmitic and linoleic acids and the major phytosterol was stigmasterol. In addition steryl and β-amyrenyl esters were found in the flowers and the immature and the mature fruits, but these esters were not present in the flower buds. Sitosteryl ester was the major constituent of the steryl ester fraction in the fruiting stages. Phytol was found in only the flowering stage and triglycerides in only the mature fruits. The variations in the lipid constituents is discussed in relation to the stages from budding to the mature fruit.     

Non-acidic compounds induce the intense sweet taste of neoculin, a taste-modifying protein

Neoculin, a sweet protein found in the fruit of Curculigo latifolia, has the ability to change sourness into sweetness. Neoculin turns drinking water sweet, indicating that non-acidic compounds may induce the sweetness. We report that ammonium chloride and certain amino acids elicit the intense sweetness of neoculin. Neoculin can thus sweeten amino acid-enriched foods.     

Variability for Free Sugars and Organic Acids in Capsicum chinense

Variability in the concentrations of the chemical constituents that contribute to fruit flavor in Capsicum chinense is poorly documented in the scientific literature. We surveyed fruit of 216 landraces and cultivated varieties of Capsicum chinense acquired from North, Central, and South America, and analyzed these for concentrations of the simple sugars sucrose, glucose, and fructose, and citric, malic, succinic, fumaric, and ascorbic acids. Concentrations (mg/100 g Fresh Weight (FW) of whole fruit) of sucrose, glucose, and fructose in fruit of this species ranged from 0.0 to 150, 68 to 701, and 101 to 823, respectively. The total of these sugars (sucrose+glucose+fructose) ranged from 198 to 1543 mg/100 g FW. Concentrations of organic acids ranged from 0.0 (not detected) to 818, 430, 340, and 232 mg/100 g FW for citric, malic, fumaric, and succinic acids, respectively. However, the relative ranking in the concentrations of the individual acids was genotype‐dependent. Total ascorbic‐acid values ranged from 30 to 1466 mg/100 g FW. These data serve to document the range in the concentrations of individual sugars and acids present in mature C. chinense fruit and suggest that this variability may lend itself to studies involving the synthesis and/or metabolism of compounds associated with fruit flavor.     

Effect of sweetener type and of sweetener and acid levels on temporal perception of sweetness, sourness and fruitiness

Sweetness, sourness and fruitiness of 18 orange-flavored solutions,with three levels of citric acid (0.75, 1.5, 2.25 g/1) and threeequi-sweet levels of either sucrose (80, 100, 120 g/l) or aspartame(0.6, 0.7, 0.8 g/l), were evaluated by time–intensitymethodology. At these concentrations, a larger range in sournessintensity than in sweetness was produced, resulting in greatersuppression of sweetness by increasing acid levels than of sournessby increasing sweetener levels. Although aspartame samples hada longer duration of sweetness and fruitiness, sucrose and aspartamedid not interact differently with the sourness of citric acid.Fruitiness intensity and duration was enhanced by both sweetnessand sourness, but to a greater extent by sourness. Whether thisenhancement is attributable to a cognitive association of sweetnessor sourness with fruitiness or is due to the inability of thesubjects to separate sweet and sour tastes from orally perceivedfruity flavor cannot be concluded from this study.     

Non-Acidic Compounds Induce the Intense Sweet Taste of Neoculin,a Taste-Modifying Protein

Neoculin, a sweet protein found in the fruit of Curculigo latifolia, has the ability to change sourness into sweetness. Neoculin turns drinking water sweet, indicating that non-acidic compounds may induce the sweetness. We report that ammonium chloride and certain amino acids elicit the intense sweetness of neoculin. Neoculin can thus sweeten amino acid-enriched foods.     

Phenolic constituents of tomato fruit cuticles

Chalconaringenin, naringenin, naringenin-7-glucoside, and m- and p-coumaric acids have been identified in the fruit cuticles of three tomato cultivars. The phenolic content of the cuticles increased substantially during fruit development, those from immature green and mature ripe fruits of cv Ailsa Craig yielding respectively 2.8 and 61 μg/cm² (representing 1.4 and 6% of the total membrane wt). Coumaric acids, present only in the ‘cutin-bound’ phenolics, increased from 2 to 24 μg/cm² during fruit development. Flavonoids, synthesized mainly during the climacteric, occurred free in the epicuticular (0.3–7.2 μg/cm²) and cuticular (0.7–5.7 μg/cm²) phenolics but the major part of this class of constituents in ripe fruit cuticles was also ‘bound’ to the cutin matrix (30–43 μg/cm²). The composition of the flavonoid fraction was controlled by the spectral quality of incident radiation, red light favouring the formation of chalconaringenin.