Preparation and characterisation of dietary fibre from sugar beet pulp

Dried sugar beet pulp was ground and washed with 95% ethanol in order to obtain a colourless and odourless product which could be used as dietary fibre after drying and sieving. Sugar beet fibre had the same chemical composition as the initial pulp: 26–32% of hemicelluloses, 22–24% cellulose, 21.5–23% uronic acids, ～1–2% lignin, ～7–8% protein, 7.5–12% ash and ～0.5% residual sucrose. The main physicochemical properties such as density, cation exchange capacity (～0.6 meq g^?1) and water holding capacity (24–32 g g^?1) were determined. The water holding capacity of sugar beet fibre was only slightly affected by pH and ionic strength (adjusted by NaCl or CaCl₂) but it held less water in the H⁺ form than in the salt form, Na⁺ or Ca²⁺.     

Studies on rats fed a dietary fibre preparation from sugar beet

 Groups of 15 female rats were fed ad libitum for 4 weeks with a standard diet containing 0, 2.5, 5 or 10% of a dietary fibre (DF) preparation made on a laboratory scale from sugar beet pulp. This preparation had a total DF content of 72.2%. Its major components were 36.7% cellulose, 16.9% pectin, 16.8% hemicelluloses (HC) and 11.0% protein. The DF preparation from sugar beet exhibited a water-binding capacity (WBC) of 8.9 g H₂O/g. As the proportion of DF preparation in the diet increased, up to 15.8% total DF, 4.6% cellulose and 1.9% pectin were found in the feeds. The WBC of the diets was estimated to be 1.4–2.9 g H₂O/g. At the end of the experiment, 20.3–64.1% total DF, 10.3–38.2% cellulose, 0.2–7.8% pectin, 4.3–9.2% HC pentoses and 4.3–10.3% HC hexoses were determined in caecum contents (ca. 0.6 g dry weight/rat). The following proportions were found in faeces (3rd week; 1.4–1.9 g dry weight/rat): 34.5–56.9% total DF, 19.5–36.1% cellulose, 6.4–8.4% HC pentoses, 7.4–8.3% HC hexoses. The WBC of faeces ranged from 3.7 g H₂O/g to 4.9 g H₂O/g. About 30–50% of the daily intake of DF appeared in the faeces. Higher amounts of total DF, pectin and HC pentoses were fermented by gastrointestinal microflora as the concentration of DF preparation from sugar beet in the diet increased. In addition, the fermentation of different DF components could be shown by the monosaccharide composition of caecum contents and faeces. Received: 21 October 1997     

甜菜废粕吸附性能的研究

研究了甜菜废粕吸附溶液中Cu2＋的能力,采用间歇吸附试验来评价甜菜废粕对Cu2＋的除去效率,吸附速率相对较快,在60min即可达到平衡。在间歇试验条件下,最高可达90％的去除率。废粕吸附能力与溶液pH有关,pH5．5时最大吸附Cu2＋量可达30．9mg／g。废粕添加量为8g／L足以达到最佳处理效果。     

外源激素处理对甜菜农艺性状及产质量的影响

以甜菜丰产型品种“SD13829”和高糖型品种“04BS02”为材料,研究了喷施2,4-D、GA3、6-BA、ABA 4种外源激素对甜菜农艺性状及产质量的影响.结果表明,GA3能促进株高的增长,ABA抑制株高的增长和叶面积的扩大.2,4-D能促进叶面积的扩大.6-BA、2,4-D和GA3能不同程度地提高地上部干物质积累量.在甜菜生育后期喷施ABA明显抑制甜菜地上部生长,促进地下部干物质积累;喷施2,4-D会造成地下部干物质减少.在块根增长期喷施4种外源激素均能提高块根鲜重,但对两品种含糖率无影响.在糖分积累期喷施4种外源激素对单株根重无明显影响,喷施2,4-D降低了两品种的含糖率,喷施ABA提高了两品种的含糖率.     

Structural modifications of sugar beet pectin and the relationship of structure to functionality

The emulsifying properties of sugar beet pectin (SBP) were investigated in relation to its molecular structure. SBP has been subjected to an enhancement process, and this material was here compared with conventional non-enhanced SBP. The oil-in-water emulsification properties of both were compared at 1.5% concentration at pH 3.25, using 15% middle-chain triglyceride as the oil phase. Their emulsification behavior after various enzyme treatments decreased in the order: protease > arabinanase/galactanase mixture > polygalacturonase. The enzyme treatment also decreased the molecular weight of SBP. Protease degraded the high molecular weight carbohydrate–protein complex. Arabinanase/galactanase mixture was more effective in decreasing the emulsification performance than polygalacturonase. The results confirm the key role of protein as the anchor for the oil droplets and identify also the contribution of the neutral lateral chains in stabilizing emulsions by forming a hydrated layer. Protein also aggregates, which functions as a linker for the association of the carbohydrate chains consequent to the enhancement process.     

Effect of extraction conditions on the yield, purity and surface properties of sugar beet pulp pectin extracts

The extraction of pectins from sugar beet pulp was carried out in an aqueous acid medium under different conditions using a full two-state experimental design for three extraction parameters (pH, temperature and time). The yields of the extracted pectins ranged from 4.1% to 16.2%. Their contents in pectin constituents were 35.2–76.3% galacturonic acid, 6.8–32.9% neutral sugars, 2.0–4.2% methoxy groups, 0.8–3.8% acetyl groups, and 0.1–0.7% ferulic acid. Moreover, protein residues were present in all the extracts within the range of 0.9–6.8% and varied with the extraction conditions. On high performance size exclusion chromatography, the elution pattern of the acid-extracted pectins showed a wide molar mass distribution consisted of two relatively broad peaks. Their weight-average molar mass values determined by HPSEC-RALLS ranged widely from 20,200 to 90,100 g/mol. Most of the extracted pectins were surface-active, and some of them were quite able to produce and stabilize with effectiveness oil-in-water emulsions. Thus, it was inferred that yield, physico-chemical characteristics and surface properties of acid extracted pectins from sugar beet pulp were influenced by the extraction conditions.     

Effects of the proteinaceous moiety on the emulsifying properties of sugar beet pectin

The role of the proteinaceous moiety in emulsifying was investigated using pectin from sugar beet as a model polysaccharide. Physicochemical and macromolecular characteristics of sugar beet pectin were examined with or without an enzymatic modification using multiple acid-proteinases. The enzymatic modification decreased the total protein content from 1.56±0.15% to 0.13±0.02% by the Bradford method without significant change in ferulic acid or most constitutional sugars. It also decreased the weight-average molecular weight (M_w) from 517±28 to 254±20 kg/mol and the z-average root-mean-square radius of gyration from 43.6±0.8 to 35.0±0.6 nm. Emulsifying properties of the polysaccharide with or without the enzymatic modification were evaluated by emulsion droplet size and creaming stability of O/W emulsions (pH 3.0) containing 15 w/w% middle-chain triglyceride and 1.5 w/w% sugar beet pectin as main constituents. The modification increased the average diameter (d_3,2) of emulsion droplets from 0.56±0.04 to 3.00±0.25 μm immediately after the preparation, suggesting a decrease in the emulsifying activity. It caused the creaming of the emulsions during incubation at 60 °C, which was in line with the finding that macroscopic phase separation occurred only in the presence of the modified pectin after storage at 20 °C for a day, suggesting a decrease in the emulsion stabilizing ability. The modification also decreased significantly the amount of the pectin fraction that adsorbed onto the surface of emulsion droplets from 14.58±2.21% to 1.22±0.03% and the interfacial concentration of the polysaccharide from 1.42±0.23 to 0.45±0.05 mg/m², where the proteinaceous materials in the pectin molecules activated the oil-water interface. Results from the present study suggest an important role of the proteinaceous moiety to explain the emulsifying properties of sugar beet pectin as in the case of gum arabic and soy soluble polysaccharide.     

绿豆皮纤维素的超声波-微波联合辅助提取及其性质研究

以绿豆皮为原料,采用超声波-微波联合辅助碱法提取其中的纤维素,研究了Na OH质量分数、Na OH添加量、超声波-微波联合作用时间、微波功率及脱色时间这5个因素对绿豆皮纤维素得率、膨胀力及持水力的影响,并采用傅里叶变换红外光谱(FT-IR)对绿豆皮纤维素的微观结构进行了表征。结果表明:与碱提取法、超声波或微波单独辅助碱提取法相比,超声波-微波联合辅助碱提取法能够有效的提高绿豆皮纤维素的得率并改善其理化性质。通过单因素试验得到了绿豆皮纤维素提取的最佳工艺条件:Na OH质量分数10%、Na OH添加量15 m L/g、超声波-微波联合作用时间15 min、微波功率300 W、脱色时间90 min,在此条件下,获得的绿豆皮纤维素得率为44.91%,膨胀力为4.01 m L/g,持水力为7.16 g/g。绿豆皮纤维素的红外光谱分析结果表明,超声波-微波联合辅助碱法提取的绿豆皮纤维素特征峰没有发生明显变化,且木质素残留较少。本研究结果可以为废弃绿豆皮的再利用提供参考。     

Application of decolorization on sugar beet pulp in bread production

The aim of this research is the examination of the decolorizing effect of hydrogen peroxide, on sugar beet fibers, which oxidizes the precursors of colored matter and the colored products from enzymatic reactions, by creating uncolored compounds. The advantage of hydrogen peroxide is that its surplus separates into water and hydrogen under the effects of temperature, light, and ions of alkaline and heavy metals and so, non-sucrose compounds do not get into the system. The color change of sugar beet dietary fibers is examined depending on the hydrogen peroxide concentration (in the range from 5 to 20 g H₂O₂/1,000 cm³), the pH value (in the range from 5 to 11), and the time of reaction (in the range from 1 to 12 h) at a temperature of 30 °C. To obtain the best effects of decolorized dietary fibers in white bread production the quality of the raw material is defined. The parameters for the preparation of the bread are chosen (the amount and particle size of the fibers, the amount of water and the mode of its addition) as are the additives, which results in good-quality white bread with sugar beet fibers.     

Effect of chemical treatments of sugar beet fibre on their physico-chemical properties and on their in-vitro fermentation

Chemically treated and dried sugar beet fibres were fermented in vitro in order to study the effects of chemical and physico-chemical parameters of dietary fibre on their colonic fermentation. Sugar beet fibre was treated with dilute alkali, removing mainly acetyl and methyl ester groups, and/or with dilute acids eliminating arabinose, galactose and certain uronic acid residues. The chemical treatments led to an increase in the hydration properties and fermentability by improvement of the accessibility of the remaining polysaccharides. However, if the chemically treated fibres were dried under harsh conditions (100°C), their hydration properties and their fermentability were limited, probably because of structural collapse of the fibre matrix. Whatever the conditions for chemical treatments and drying of the sugar beet fibres, it was possible to predict their fermentability from the water-binding capacity. Because of the relationship between the physiological effects of dietary fibres and the extent to which they are fermented, this result underlines the importance of the physico-chemical characterisation of the fibre in order to acquire a better knowledge of their physiological effects.     

Enzyme catalyzed oxidative gelation of sugar beet pectin: Kinetics and rheology

Sugar beet pectin (SBP) is a marginally utilized co-processing product from sugar production from sugar beets. In this study, the kinetics of oxidative gelation of SBP, taking place via enzyme catalyzed cross-linking of ferulic acid moieties (FA), was studied using small angle oscillatory measurements. The rates of gelation, catalyzed by horseradish peroxidase (HRP) (EC 1.11.1.7) and laccase (EC 1.10.3.2), respectively, were determined by measuring the slope of the increase of the elastic modulus (G′) with time at various enzyme dosages (0.125–2.0 U mL⁻¹). When evaluated at equal enzyme activity dosage levels, the two enzymes produced different gelation kinetics and the resulting gels had different rheological properties: HRP (with addition of H₂O₂) catalyzed a fast rate of gelation compared to laccase (no H₂O₂ addition), but laccase catalysis produced stronger gels (higher G′). The main effects and interactions between different factors on the gelation rates and gel properties were examined in response surface designs in which enzyme dosage (0.125–2.0 U mL⁻¹ for HRP; 0.125–10 U mL⁻¹ for laccase), substrate concentration (1.0–4.0%), temperature (25–55 °C), pH (3.5–5.5), and H₂O₂ (0.1–1.0 mM) (for HRP only) were varied. Gelation rates increased with temperature, substrate concentration, and enzyme dosage; for laccase catalyzed SBP gelation the gel strengths correlated positively with increased gelation rate, whereas no such correlation could be established for HRP catalyzed gelation and at the elevated gelation rates (>100 Pa min⁻¹) gels produced using laccase were stronger (higher G′) than HRP catalyzed gels at similar rates of gelation. Chemical analysis confirmed the formation of ferulic acid dehydrodimers (diFAs) by both enzymes supporting that the gelation was a result of oxidative cross-linking of FAs.     

Sucrose accumulation and osmotic potentials in sugar beet at increasing levels of potassium nutrition

In a pot experiment sugar beet Beta vulgaris L. ssp. vulgaris, cv. Kawetina, was grown on alluvial soil (21 mg exchangeable K 100 g^?1) containing 0 (K₁), 20 (K₂), 40 (K₃) and 60mg fertiliser K 100 g^?1 soil (K₄). The plants were sown on 15 March 1983 and harvested on 23 June, 14 July and 30 August 1983. At final harvest root dry weight/plant had reached 269 g in K₁ and between 304 and 310 g in K₂-K₄. Sucrose values were 15% (K₁) and 17.3–17.7% of root fresh weight (K₂-K₄) respectively. The osmotic potential of the storage root decreased with increasing K nutrition and time. At final harvest ψ, was between ?1.83 (K₁) and ?2.26 MPa (K₄), 75–79% thereof being contributed by sucrose. Sucrose concentrations in press sap increased from 340–400 mM on 23 June to 475 (K₁) and 540–570 mM (K₂-K₄) at the end of August. In the same period K concentrations declined from 40–100 to 10–35 mM K⁺. The sucrose, K and Mg concentrations measured in the press sap were lower than those calculated from sucrose, K, Mg and moisture content of the storage root. This indicates that press sap from thawed storage root tissue is not fully representative. Betaine, analysed only at final harvest, significantly increased with increasing K concentrations in the storage root (r=0.83) and a significant linear regression was found between betaine and sucrose accumulation (r=0.57). This is consistent with the role of betaine as a cytosolic osmoticum for sugar beet storage tissue. Other solutes in the cytosol may also contribute to osmoregulation as sucrose accumulates in the vacuoles.     

Characterisation of sugar beet pectin fractions providing enhanced stability of anthocyanin-based natural blue food colourants

The bathochromic effect resulting from the addition of sugar beet pectin (SBP) to black currant juice, purified anthocyanins (ACN-E) and purified polyphenol extracts comprising both anthocyanins and non-anthocyanin phenolics (PP-E), respectively, were monitored by VIS spectroscopy at varying pH relevant to food formulations (pH 3.6–5.0). Furthermore, a low molecular pectic polysaccharide fraction (PPF) was isolated from SBP using 70% aqueous 2-propanol and further characterised with respect to its chemical composition and mineral content. The marked bathochromic effect was found to be due to the formation of anthocyanin–metal chelate complexes. Only at pH 5.0 SBP entailed a moderate bathochromic shift of 12 nm in model solutions containing ACN-E. This effect was enhanced in PPF model solutions resulting in a λ_max shift up to 50 nm, bringing about an intense blue colour. The bathochromic shift was boosted with increasing pH and upon purification of the anthocyanins. In contrast, after SBP and PPF addition to black currant juice, the bathochromic effect was almost annihilated. Model solutions were stored at 20 °C in the dark for 12 days, and optimum stability of the blue colour was observed at pH 5.0.     

Stabilization of oil-in-water emulsions by enzyme catalyzed oxidative gelation of sugar beet pectin

Enzyme catalyzed oxidative cross-linking of feruloyl groups can promote gelation of sugar beet pectin (SBP). It is uncertain how the enzyme kinetics of this cross-linking reaction are affected in emulsion systems and whether the gelation affects emulsion stability. In this study, SBP (2.5% w/v) was mixed into an oil-in-water emulsion system (4.4% w/w oil, 0.22% w/w whey protein, pH 4.5). Two separate, identically composed, emulsion systems were prepared by different methods of preparation. The emulsions prepared separately and subsequently mixed with SBP (referred as Mix A) produced significantly larger average particle sizes than the emulsions in which the SBP was homogenized into the emulsion system during emulsion preparation (referred as Mix B). Mix B type emulsions were stable. Enzyme catalyzed oxidative gelation of SBP helped stabilize the emulsions in Mix A. The kinetics of the enzyme catalyzed oxidative gelation of SBP was evaluated by small angle oscillatory measurements for horseradish peroxidase (HRP) (EC 1.11.1.7) and laccase (EC 1.10.3.2) catalysis, respectively. HRP catalyzed gelation rates, determined from the slopes of the increase of elastic modulus (G′) with time, were higher (P < 0.05) than the corresponding laccase catalyzed rates, but the final G′ values were higher for laccase catalyzed gels, regardless of the presence of emulsions or type of emulsion preparation (Mix A or Mix B). For both enzymes, rates of gelation in Mix A were higher (P < 0.05) than in Mix B, and higher stress was needed to break the gels in Mix A than in Mix B at similar enzyme dosage levels. These differences may be related to a lower availability of the feruloyl groups for cross-linking when the SBP was homogenized into the emulsion system during preparation.     

Preparation and properties of a white protein fraction in high yield from sugar beet (Beta vulgaris L) leaves

Chlorophyll-free protein has been recovered at a yield in excess of 50 % from sugar beet (Beta vulgaris L) leaf juice after two successive pH treatments. This corresponds to about 60 kg of white protein per hectare. The main component of the final preparation is ribulose-1,5-bisphosphate carboxylase (EC 4.1.1.39). Compared with the unfractionated protein from leaf extracts, the white protein preparation has higher contents of tyrosine, threonine, glutamic acid and proline and lower ones of isoleucine, lysine (although still high: 76mg g^?1) and glycine. The content of methionine is high (24mg g^?1) probably as a result of the addition of sulphite during protein extraction. The white protein preparation has a low level of ether extractives (17mg g^?1) and a moderate ash (52mg g^?1) content. The white protein is rapidly degraded by pepsin, trypsin and pancreatic juice.     

除草剂对免耕直播甜菜除草效果评价

使用乙氧呋草黄,甜安宁及二氯吡啶酸等除草剂在免耕直播甜菜田苗前及苗后进行除阔叶除草方面处理,试验表明：直播免耕田甜菜杂草防除有两个关键时期,即播后苗前时期和杂草2-4片叶时期.从播后苗前第一次喷施开始,经过5次喷施,可以实现较理想的除草效果.播后苗前喷施乙氧呋草黄进行苗前处理;在甜菜苗期,杂草2-4片叶时乙氧呋草黄与甜菜安宁、甲酯化植物油配合使用可以达到较好的防除效果.     

甜菜果胶制备藻油乳化液及其稳定性研究

藻油富含对人体非常重要的多不饱和脂肪酸DHA（二十二碳六烯酸）,但其极易被光、热和氧等因素诱使发生氧化反应。防止氧化反应发生,制备成稳定的油／水乳化液将其包埋成为其在食品中应用的关键问题。本研究采用甜菜果胶为乳化剂对其进行乳化包埋,研究了乳化条件如乳化剂量、油水比率、pH和均质条件对乳化液稳定性的影响。结果表明,最适的乳化条件为：乳化剂添加量在2．5％以上,油水比1：10,pH〉5,35MPa压力下均质3个循环得到比较稳定的乳化液。     

甜菜果胶理化性质及加工适用性质研究

本文对甜菜果胶（SBP）的各项理化性质进行了研究,并与商品柑橘果胶（CP）进行对比。研究了果胶中半乳糖醛酸、总糖、蛋白质含量,酯化度,乙酰度等基本理化性质。然后通过傅里叶红外光谱扫描、果胶分子量等指标,研究了甜菜果胶分子结构的基本特性。通过乳液粒径,乳化活性,ζ-电位和显微观察的手段,对其乳化性质进行评价。最后从流体力学性质出发,考察了果胶浓度和温度对其表观黏度的影响。发现甜菜果胶中蛋白质和阿魏酸含量较高,分子量和表观黏度较柑橘果胶更小。且甜菜果胶的乳化性质优于牛血清白蛋白和阿拉伯胶。通过该研究明确了甜菜果胶的加工适应性,同时为进一步研究甜菜果胶的乳化及凝胶特性提供了理论依据。      

Bathochromic and stabilising effects of sugar beet pectin and an isolated pectic fraction on anthocyanins exhibiting pyrogallol and catechol moieties

The formation of anthocyanin–metal chelates, exhibiting intense blue colours was monitored over a period up to 10 weeks. Evaluating normalised absorption spectra in the range of 580–700 nm and their proportion of the total area under the curve (AUC), provided information about the blue colour hue, intensity and stability. Colour stability in model solutions containing commercial sugar beet pectin or an isolated pectic polysaccharide fraction (PPF) therefrom, both being naturally enriched in aluminium and ferric ions, was assessed in a pH range of 3.6–7.0. The pectic structures stabilised anthocyanin–metal chelates, and thus blue colours by efficiently preventing complex precipitation. Highest bathochromic shifts and most intense blue colours were observed in PPF model solutions containing delphinidin-3-glucoside (Dpd-3-glc), exhibiting a pyrogallol moiety in the flavylium B-ring, compared to cyanidin- (Cyd-3-glc) and petunidin-3-glucoside (Pet-3-glc), both carrying a catechol substituted B-ring. Hue and intensity of the blue colour at pH 5.0 were only insignificantly influenced by the buffer system except for citrate and phosphate buffers, which both annihilated anthocyanin–metal chelate formation. The blue colours faded following first order kinetics. Best stabilities as deduced from storage experiments performed at 20 ± 2 °C in the dark were observed for Dpd-3-glc. In contrast, Cyd-3-glc displayed shortened half-life values, whereas blue Pet-3-glc chelates decomposed rapidly. These results demonstrate that the solubilisation of anthocyanin–metal chelates by pectic structures is a promising option for developing water soluble natural blue food colourants.     

Laccase mediated conjugation of sugar beet pectin and the effect on emulsion stability

Laccase catalyzes intermolecular cross-links between ferulic acid of sugar beet pectin (SBP). Conjugation of SBP by laccase was confirmed by increased molecular weight, monitored by size exclusion chromatography, combined with multi-angle laser light scattering (SEC–MALLS), by reduced ferulic acid concentration detected at UV 325 nm, as well as by increased particle size. In addition, cross-linked SBP developed a more compact, branched structure as verified by a smaller root mean square (RMS) when molecular weight increased. Emulsions prepared with conjugated SBP had significantly smaller d_4,3 diameter and uniform droplet size, with more negative ζ-potential than non-treated SBP, during 30 days storage at 37 °C. The d_4,3 diameter was 5.3 μm and 3.8 μm for SBP and conjugated SBP, respectively. Covalently conjugated SBP has increased functionality and improved emulsion stability, most likely attributable to development of thick layer at the oil interface.