Sensory quality and appropriateness of raw and boiled Jerusalem artichoke tubers (Helianthus tuberosus L.)

BACKGROUND: The aim of the present study was to investigate the sensory attributes, dry matter and sugar content of five varieties of Jerusalem artichoke tubers and their relation to the appropriateness of the tubers for raw and boiled preparation. RESULTS: Sensory evaluation of raw and boiled Jerusalem artichoke tubers was performed by a trained sensory panel and a semi‐trained consumer panel of 49 participants, who also evaluated the appropriateness of the tubers for raw and boiled preparation. The appropriateness of raw Jerusalem artichoke tubers was related to Jerusalem artichoke flavour, green nut flavour, sweetness and colour intensity, whereas the appropriateness of boiled tubers was related to celeriac aroma, sweet aroma, sweetness and colour intensity. In both preparations the variety Dwarf stood out from the others by being the least appropriate tuber. CONCLUSION: A few sensory attributes can be used as predictors of the appropriateness of Jerusalem artichoke tubers for raw and boiled consumption. Knowledge on the quality of raw and boiled Jerusalem artichoke tubers can be used to inform consumers on the right choice of raw material and thereby increase the consumption of the vegetable. © 2012 Society of Chemical Industry     

Changes in physicochemical characteristics and antioxidant activities of Jerusalem artichoke tea infusions resulting from different production processes

The physicochemical properties of Jerusalem artichoke (Helianthus tuberosus L.) tea infusions produced using drying, roasting, puffing, and extrusion methods were investigated. The surfaces of puffed and extruded artichokes were more porous than the surfaces of dried and roasted artichokes. The water solubility index was highest for tea infusions of extruded and puffed artichokes. The total phenolic contents and antioxidant activities of artichoke tea infusions were in the order of puffed>extruded> roasted>hot air dried. Moderate and fine particle sizes used for tea infusions had the highest browning degrees and antioxidant activities, similar to total phenolic contents. Basic data are provided with implications for further development of processed food products, including tea bags using Jerusalem artichoke.     

Involvement of Polyphenols in the After-Cooking Darkening of Gamma Irradiated Potatoes

Peeling of potatoes prior to boiling reduces the intensity of gamma irradiation induced after-cooking darkening of the tuber flesh. Polyphenols in the flesh of cooked whole tubers, pre-peeled tubers and in the cooking water were determined to examine its role in the darkening. Pre-peeling results in increased leaching of polyphenols from the flesh into the cooking water thus reducing the amount available for the formation of iron-phenolics complex responsible for darkening. The results indicate a strong correlation between low polyphenol levels and the reduction in after-cooking darkening of pre-peeled potatoes.     

菊芋泡菜贮藏期间非酶褐变的研究

研究不同包装材料和加工用水对菊芋泡菜褐变的影响,并对其贮藏期间部分理化指标的变化进行测定,初步揭示菊芋泡菜在贮藏期间发生褐变的机制。结果表明,菊芋泡菜贮藏期间发生的褐变主要是多酚的氧化聚合以及美拉德反应导致的非酶褐变,而低浓度的金属铁离子并不会导致褐变的发生。在菊芋泡菜中添加不同的抗褐变剂(异抗坏血酸钠、柠檬酸亚锡二钠和EDTA),可以减少菊芋泡菜在贮藏期间的褐变。加速贮藏实验表明,柠檬酸亚锡二钠是菊芋泡菜贮藏期间良好的抗褐变抑制剂。     

Changes in extractability and antioxidant activity of Jerusalem artichoke (Helianthus tuberosus L.) tubers by various high hydrostatic pressure treatments

This study investigated changes in the extraction characteristics of Jerusalem artichoke (Helianthus tuberosus L.) tubers (JA) using high hydrostatic pressure (HHP) treatment alone and in combination with enzymes and/or fermentation. HHP treatment of JA increased the soluble solid content and decreased the turbidity compared to the control group that received hot-water extraction. This indicates improved extractability of JA by HHP treatment alone or in combination. Combined HHP treatment with enzymes increased the contents of non-reducing sugars, fructooligosaccharide (FOS), and free amino acids in the extracts compared to those of control, thus activating browning reaction. Extraction of fermented JA by HHP treatment with or without enzyme showed increased polyphenol content as well as improved 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and superoxide dismutase (SOD) like activity compared to the control group. Taken together, HHP treatment of fermented JA with enzymes significantly improved the extractability of bioactive molecules such as phenolics and FOS compared to conventional water extraction or HHP treatment alone. Our results provide useful information for the improvement of raw material extraction by HHP treatment in combination.     

Soluble dietary fibres in Jerusalem artichoke powders: composition and application in bread

Powders of tubers from Jerusalem artichoke (Helianthus tuberosus, L.), cultivar Gigant, of different harvesting times (autumn and spring) were applied in bakery products, particularly in wheat/rye bread. The quality of this bread was compared to bread with cereal flours substituted with commercial products as Raftilin ST and Raftilose P95. Compared to standard and substituted bread, Jerusalem artichoke bread shows a high quality in organoleptic evaluation (grade I with 36.5 and 37.5 scores). In utilised Jerusalem artichoke powders (JAPs) the amount of fructan (inulin) hydrolysis to fructose during the baking process depends on its initial degree of polymerisation (dp). With JAP of autumn harvest (fructan: dpn = 9.9, dpw = 21.8) less fructose (24.6%) is formed than with those of spring harvest (fructan: dpn = 4.9, dpw = 7.1) (40.7%). Compared to this bread, substitution with commercial products Raftilin ST (inulin: dpn = 8.4, dpw = 17.4) and Raftilose P95 (fructo-oligosaccharides: dpn = 2.7, dpw = 3.0) yields 11.9% and 45.8% of fructose upon total hydrolysis, respectively. The loss of fructan content by the bakery process is 38% in bread with JAP of autumn and 43% in bread with JAP of spring harvest; Raftilin ST- and Raftilose P95-bread come up with loss of fructan content of 35% and 47%, respectively.     

Effect of Foliar Application of Auxin on the Quality of Potatoes

Katahdin and Kennebec potatoes were sprayed with 10^?5M auxin at the beginning of flowering. Tubers from the auxin-treated plants were compared with untreated controls for phenolic content, enzymatic discoloration, total nitrogen, nonprotein nitrogen, free ammo acids, lipids, minerals, and ascorbic acid content. In both varieties auxin increased the phenols and enzymatic discoloration. However, no differences were observed in fatty acid composition and ascorbic acid content. Total nitrogen, nonprotein nitrogen, free amino acids, crude lipid, phospholipid and magnesium content were higher, and iron lower, in Katahdin tubers from the treated plants.     

Studies on enzymic browning of potatoes (Solanum tuberosum). I. Phenoloxidases and phenolic compounds from different varieties (author's transl)]

31 samples of potato varieties with slow, medium and fast rates of browning were studies. Characteristic enzyme patterns were obtained from polyacrylamide gel electrophoresic of the phenoloxidases of varieties with different discolouration rates. The differences lie mainly in the intensities of the enzyme bands. The qualitative determinaiton of the phenols showed no significant differences. Tyrosine, chlorogenic acid and caffeic acid produce coloured oxidation products; the characteristic colour gradations of in vivo browning were only observed in the presence of tyrosine. It is concluded that the same reactions take place during the discolouration of all the varieties.     

Free radical scavenging activities and bioactive substances of Jerusalem artichoke (Helianthus tuberosus L.) leaves

The total phenolic content and radical scavenging activities of Jerusalem artichoke (Helianthus tuberosus L.) leaves were investigated. Results indicated that the ethyl acetate fraction contained the highest total phenolic content (266.69 ± 2.51 mg GAE/g dry extract) accompanied with strongest free radical scavenging abilities. Following an in vitro radical scavenging activity-guide fractionation procedure, six phenolic compounds which strongly quenched free radicals were separated from ethyl acetate fraction. Among them, 3-O-caffeoylquinic acid and 1,5-dicaffeoylquinic acid played a dominant role due to their strong free radical scavenging abilities and their high contents. The content of 3-O-caffeoylquinic acid in n-butanol fraction was 74.58 ± 1.05 mg/g, while 1,5-dicaffeoylquinic acid in ethyl acetate fraction was 104.51 ± 2.86 mg/g. The results imply that the leaves of Jerusalem artichoke might be a potential source of natural antioxidants.     

Feeding Jerusalem artichoke (Helianthus tuberosus) to pigs

Weaned pigs were fed diets with added Jerusalem artichoke for 28 days. In a first trial, the pigs received raw tubers in addition to their normal ration. In a second trial, the pigs received dried Jerusalem artichoke (10–60 g kg^-1) in the diet. Pigs eating the raw tuber had significantly increased body weight gains due to the consumption of the raw tuber, but significantly decreased feed efficiency. Adding dried Jerusalem artichoke to the diet significantly increased weight gains. Feed efficiency was improved, but not significantly. Faecal valeric acid concentration was significantly increased in animals eating Jerusalem artichoke.     

乳酸菌发酵菊芋汁及其风味的研究

对不同品种和产地的菊芋主要成分进行了测定,并利用乳酸菌对菊芋汁进行发酵,研究了不同乳酸菌在菊芋汁中的生长规律、低温存活性及发酵菊芋汁中主要风味物质。结果表明,4种乳酸菌在菊芋汁中均生长良好,最高活菌数可达到109CFU/mL;菊芋汁经乳酸菌发酵后具有良好风味,其风味的差异与发酵菌种有关;发酵菊芋汁中乳酸菌在4℃低温贮藏过程中具有较好的低温存活性,4周后活菌数保持在108CFU/mL。菊芋汁适用于开发成新的功能性乳酸菌饮料。     

Causes of Browning in Pear Juice Concentrate During Storage

Pear juice was treated with cation exchange resin, PVPP, XAD-4, oxygen, and various resin combinations. Samples were concentrated and increases in browning measured during storage at 37°C. Analytical determinations included α-amino nitrogen, total phenolics, metal ions, ascorbic acid, and dehydroascorbic acid. While XAD-4 and PVPP were more effective in lowering phenolic content and reducing initial color, cation exchange treatment removed amino acids and was most effective in preventing browning and providing flavor stability. Addition of glycine to cation-exchange treated samples restored browning rates. Reductone formation during storage resulted in an apparent increase in ascorbic acid. It was concluded that Maillard browning reactions predominated during storage.     

果蔬酶促褐变机理的研究进展

酶促褐变对果蔬在加工保鲜过程中的品质有重大影响，有关酶促褐变机理的相关研究也越来越多。本文整理归纳了国内外围绕褐变机理进行的多酚氧化酶和酚类底物的相关研究，包括对多酚氧化酶种类、催化位点、提取、分离、纯化、活性测定方法的介绍；酚类化合物种类、含量变化及其变化原因的阐述；酚类酶促氧化反应、醌的生成途径、次级代谢过程、氧化终产物特性以及抗褐变剂抑制酶促褐变机理的报道，以期为酶促褐变机理的系统深入研究提供借鉴与参考。     

Studies on enzymic browning of potatoes (Solanum tuberosum). II. The quantitative relationship between browning and its causative factors (author's transl)]

Ten potato varieties, with different rates of browning, were analyzed quantitatively for phenoloxidase, tyrosine, chlorogenic acid, caffeic acid, and for reducing substances (ascorbic acid). The rate of tyrosine turnover was calculated from the data. The fact that the further reactions of the primary oxidation products leading to browning only take place after complete oxidation of the reducing substances, was taken into account. This leads to the same classification of the varieties as does visual observation of the rate of discolouration. Thus a clear relationship between browning and potato constituents is demonstrated.     

枸杞酒发酵过程中的褐变

通过测定枸杞酒发酵过程中和陈酿过程中多酚氧化酶（PPO）和过氧化物酶（POD）活性变化规律,总酚、黄酮、10种单体酚、VC和美拉德反应中间产物五羟甲基糠醛（5-HMF）的变化规律以及对应时期的褐变度变化,找到引起褐变的主要原因。结果显示,单体酚芦丁、绿原酸、阿魏酸、对羟基苯甲酸和对香豆酸在发酵液中含量较多,对褐变度影响较大。同时,VC氧化降解以及糖与氨基酸的美拉德反应也参与了褐变。结论为发酵过程中酶促褐变与非酶促褐变同时存在,酚类物质同时参与酶促和非酶促褐变反应,这是引起褐变的主要原因。     

无核白葡萄干制过程中酚类物质的变化及其与褐变的关系

为研究无核白葡萄干制过程中酚类物质变化及其与褐变的关系,将无核白葡萄进行荫干处理,测定其脱水干制过程中总酚含量、褐变度、酚类物质组成和含量,并鉴定酶促褐变底物。结果表明：无核白葡萄在干制过程中总酚含量总体呈降低趋势,在无核白葡萄出现明显褐变时总酚含量有所增加,同时褐变度明显上升。无核白葡萄中主要的酚类物质有14 种,其中6 种是酶促褐变的底物,分别为原花青素B2、对羟基肉桂酸、儿茶素、反式-咖啡酸、顺式-白藜芦醇、阿魏酸,最主要的酶促褐变底物为儿茶素。干制过程中无核白葡萄褐变度与总酚、原花青素B2、对羟基肉桂酸、儿茶素、反式-咖啡酸、顺式-白藜芦醇含量呈显著或极显著相关（P＜0.05,P＜0.01）。本研究结果为提高无核白葡萄干的品质提供理论依据。     

Phenolic acid concentrations in organically and conventionally cultivated spring and winter wheat

BACKGROUND: Organic crops are often thought to contain more phenolic secondary metabolites than conventional ones. This study evaluated the influence of organic and conventional farming on concentrations of phenolic acids in spring and winter wheat cultivars. RESULTS: Five phenolic acids were identified: ferulic, sinapic, p‐coumaric, vanillic and p‐hydroxybenzoic acid. Ferulic acid was the main phenolic acid in the grain of all tested wheat varieties. Significant differences among the examined cultivars in concentration of particular compounds were observed. Concentrations of phenolic acids varied significantly in organic and conventional wheat. Levels of ferulic and p‐coumaric acids, as well as the total phenolic acid content were higher in organic crops. Concentrations of sinapic acid in spring wheat, as well as vanillic and p‐hydroxybenzoic acid levels in both types of wheat were significantly higher in conventional grains. The 1000 kernel weight (TKW) of spring and winter wheat was significantly lower in organic crops. CONCLUSION: Organically produced spring and winter wheat had significantly higher concentrations of ferulic and p‐coumaric acid as well as the total phenolic acid content than conventional wheat, though the differences in the levels of phenolics were not large. However, these differences are probably caused mainly by smaller size of organic wheat kernels (lower TKW). Copyright © 2011 Society of Chemical Industry     

Investigation of the contents of phenolic and alkaloidal compounds of gamma irradiated potatoes during storage

The contents of phenolic cinnamic acids and coumarins as well as of the glycoalkaloids of gamma irradiated potato tubers have been studied in detail. Gamma irradiation up to 3 k Gy had no effect on the glycoalkaloid contents of two potato tuber varieties during a four months storage period. The phenolic compounds behave differently and show a considerable change during storage in potatoes irradiated at the highest dose level, 3 k Gy. A time dependent change of phenolic extracts was observed. This change of phenolic compounds could be partly ascribed to the β-glycoside of scopoletin (coumarin, 7-hydroxy-6-methoxy) and was accompanied by a general decrease of chlorogenic acid, the main hydroxy-cinnamic acid of potatoes.     

Sensorically and antimicrobially active metabolite production of Lactobacillus strains on Jerusalem artichoke juice

BACKGROUND: In the tubers of Jerusalem artichoke (Helianthus tuberosus L.) the main carbohydrate is the well‐known prebiotic inulin, which is a good growth substrate for gut microorganisms. Jerusalem artichoke tuber is traditionally consumed boiled or pickled rather than in fermented form. Lactic acid bacteria are traditionally used in the production of fermented foods; nevertheless their behavior and metabolite production are considerably influenced by the substrate. The purpose of this study was to investigate the growth and production of the most important sensorically and antimicrobially active metabolites of different Lactobacillus strains on Jerusalem artichoke juice. RESULTS: All investigated strains grew well (in the range 10⁹ cfu mL^?1) in the media. The organic acids (lactic acid, 110–337 mmol L^?1; acetic acid, 0–180 mmol L^?1; and succinic acid, 0–79 mmol L^?1), hydrogen peroxide (0.25–1.77 mg L^?1), mannitol (0.06–3.24 g L^?1), acetoin and diacetyl production of strains varies not only according to the species but also from strain to strain, which will be demonstrated and discussed in the paper. CONCLUSION: Our results showed that lactobacilli can be used for the fermentation of Jerusalem artichoke, which in this form could be used, alone or mixed with other raw food material, as a new synbiotic functional food. Copyright © 2011 Society of Chemical Industry