Variation in nutrient composition of Australian retail potatoes over a 12-month period

‘Pontiac’, ‘Sebago’ and potatoes marketed under the general name of New potatoes were purchased from retail outlets in Sydney, Australia every 2 weeks over a 12-month period during 1982–83 to determine the change in composition over a season. Data are presented for water, vitamin C, starch, sugars (fructose, glucose and sucrose), dietary fibre, protein, fat, organic acids (malic, citric and oxalic acids), ash, carotenes, thiamin, riboflavin, niacin, potassium, sodium, calcium, magnesium, iron and zinc levels, edible weight and energy content. The level of vitamin C varied throughout the year from 10 to 23 mg 100 g^?1 for ‘Pontiac’, 14 to 29 mg 100 g^?1 for ‘Sebago’ and 16 to 32 mg 100 g^?1 for New potatoes with the lowest values occurring in August to September (late winter to early spring) and the highest values in December to January (mid summer). Substantial variations also occurred in the water content, which was higher, and the level of starch and hence energy content, which was lower, during the cooler months of the year. Smaller changes were noted for niacin and thiamin which were lower and sugars which were higher during the winter period.     

Determination of anthocyanins,flavonoids and phenolic acids in potatoes. I: Coloured cultivars of Solanum tuberosum L

The major anthocyanins, flavonoids and phenolic acids in the tubers (skin and flesh), flowers and leaves of 26 cultivars of Solanum tuberosum L with coloured skins and/or flesh have been identified and quantified using analytical HPLC. Red tubers contained mostly pelagonidin-3-(p-coumaroyl-rutinoside)-5-glucoside (200–2000 μg g⁻¹ FW) plus lesser amounts of peonidin-3-(p-coumaroyl-rutinoside)-5-glucoside (20–400 μg g⁻¹ FW). Light to medium purple tubers contained petunidin-3-(p-coumaroyl-rutinoside)-5-glucoside (1000–2000 μg g⁻¹ FW) plus small amounts of malvidin-3-(p-coumaroyl-rutinoside)-5-glucoside (20–200 μg g⁻¹ FW) whilst dark purple–black tubers contained similar levels of petunidin-3-(p-coumaroyl-rutinoside)-5-glucoside together with much higher concentrations of malvidin-3-(p-coumaroyl-rutinoside)-5-glucoside (2000–5000 μg g⁻¹ FW). Tuber flesh also contained chlorogenic acid (30–900 μg g⁻¹ FW) and other phenolic acids plus low concentrations of flavonoids (0–30 μg g⁻¹ FW). Tuber skins showed much higher levels (1000–4000 μg g⁻¹ FW) of chlorogenic acid. The major anthocyanins in flowers were present as the rutinosides or other glycosides of pelargonidin, petunidin and malvidin whilst glycosides of cyanidin and delphinidin were found in some flowers, together with many of the same phenolic acids as found in tubers. The commonest flavonoids included rutin, kaempferol-3-rutinoside and two quercetin-rhamnose-glucosides. Flowers and leaves contained higher concentrations of flavonoids which fell into two patterns, with some cultivars containing high concentrations of quercetin-3-glycosides, whilst others had much lower concentrations. © 1998 SCI.     

Sensory quality and mineral and glycoalkaloid concentrations in organically and conventionally grown redskin potatoes (Solanum tuberosum)

Triangle tests were used to determine if panellists could distinguish (by tasting) cooked wedges of potatoes grown organically, either with (+) or without (?) compost, and conventionally. Mineral and glycoalkaloid analyses of tuber skin and flesh were also completed. When the skin remained on the potatoes, panellists detected differences between conventional potatoes and organic potatoes, regardless of soil treatment. However, they did not distinguish between organic treatments (± compost) when samples contained skin, or between any treatments if wedges were peeled prior to preparation and presentation. Glycoalkaloid levels tended to be higher in organic potatoes. In tuber skin and flesh, potassium, magnesium, phosphorus, sulfur and copper concentrations were also significantly higher in the organic treatments, while iron and manganese concentrations were higher in the skin of conventionally grown potatoes. Copyright © 2005 Society of Chemical Industry     

Textural and pasting properties of potatoes (Solanum tuberosum L.) as affected by storage temperature

Fresh tubers from five potato (Solanum tuberosum L.) cultivars were stored at different temperatures (4, 8, 12, 16 and 20 °C) and 80–90% relative humidity for 18 weeks after harvest to examine the effect of storage temperature on their textural and pasting properties. Texture profile analysis was performed on raw and cooked potatoes using an Instron universal testing machine to measure textural parameters such as fracturability, hardness, cohesiveness, adhesiveness and springiness. Both raw and cooked potato tubers showed a considerable reduction in all textural parameters upon storage, irrespective of the storage temperature employed. Raw potatoes showed a decrease in fracturability and hardness with increasing storage temperature, whereas their cooked counterparts showed the opposite trend. The extent of change in the textural properties of both raw and cooked potatoes also varied among the different cultivars. Fresh and stored tubers from all cultivars were freeze‐dried, ground into flours and analysed for amylose content and pasting properties. The amylose content of flours prepared from potatoes stored at 4 and 8 °C was observed to be considerably lower than that of flours prepared from potatoes stored at 16 and 20 °C. Pasting characteristics such as peak viscosity, setback and final viscosity increased with increasing storage temperature, while the reverse was observed for pasting temperature, when studied using a rapid visco analyser. Breakdown in viscosity of the flour pastes from all cultivars was considerably reduced during storage, irrespective of the storage temperature employed. Copyright © 2006 Society of Chemical Industry     

Correlation of physicochemical and nutritional properties of dry matter and starch in potatoes grown in different locations

The physicochemical and nutritional properties of dry matter and starches were studied from 13 potato varieties grown in different locations in Canada. Pearson correlation and principal component analysis were employed to examine relationships amongst variables. Phosphorus content in starch was negatively correlated to rapidly and slowly digestible starch content, while positively correlated to resistant starch content (RS) in raw dry matter and raw starch (p < 0.001). RS content of cooked starch was positively correlated to phosphorus content (0.48, p < 0.01), enthalpy of retrograded starch (0.48, p < 0.01), peak viscosity (0.52, p < 0.001) and breakdown of starch (0.43, p < 0.01). The principal component analysis grouped the 13 potato varieties by growing location, where phosphorus content in starch was the major difference. The results would imply that phosphorus content of starch was a key factor affecting physicochemical and nutritional properties of dry matter and starch in potatoes.     

Some physical and nutritional characteristics of genetically modified potatoes varying in amylose/amylopectin ratios

Transgenically modified potatoes with a large spread in amylose/amylopectin ratios were analysed both as tubers and in the form of isolated starch. Different microscopic techniques were used to study starch granules and tuber tissue. Starch gelatinisation properties and recrystallisation of amylopectin and amylose were studied by differential scanning calorimetry. Starch bioavailability and resistant starch (RS) were evaluated using enzymatic in vitro procedures. Glycaemic indices (GI) were predicted from low molecular weight carbohydrates (LMWC) contents and the in vitro hydrolysis rate of the starch moiety. For many of the examined parameters, differences of varying magnitude were found between the potato lines, especially for high amylose lines. High amylose starch granules had irregular shapes and showed only a limited swelling. Moreover, contents of RS and recrystallised amylose were elevated. GI’s for the starch moiety were reduced, though elevated contents of LMWC caused a high over-all predicted GI.     

12种马铃薯营养品质测定及综合评价

目的:筛选适宜南疆地区栽培的马铃薯品种。方法:以引进的12种马铃薯为供试材料,结合因子分析和聚类分析对12种马铃薯的营养品质进行综合评价。结果:S1蛋白质含量最高,S5可溶性糖含量和维生素C含量均最高,S12硝酸盐含量最低,S10还原糖含量与淀粉含量均最高。不同马铃薯品种营养品质指标存在很大差异,可溶性糖含量、维生素C含量、硝酸盐含量变异系数分别为47.13%,37.03%,33.38%。通过因子分析提取蛋白质含量因子、维生素C含量因子为2个主要因子,进一步采用系统聚类分析对马铃薯品质进行分类,分为3个类群。结论:S1、S5、S7、S10和S11 5个品种适宜在南疆地区推广。     

Microstructural,cooking and textural characteristics of potato (Solanum tuberosum L) tubers in relation to physicochemical and functional properties of their flours

Potato tubers from six different cultivars were freeze‐dried, ground into flour and analyzed for thermal, pasting and textural characteristics (using differential scanning calorimetry, Rapid Visco analyzer and Instron universal testing machine, respectively) to study the relationship between flour characteristics and cooked potato mealiness. The potatoes with higher sensory mealiness scores resulted in flours having lower transition and pasting temperatures, higher amylose content, setback, peak and final viscosity. The flour gels from the mealier potatoes also exhibited higher values of textural parameters such as hardness, cohesiveness, chewiness and springiness. The microstructure of the tuber parenchyma (studied using scanning electron microscopy), cooking and sensory characteristics of potatoes were found to be related to the pasting and textural characteristics of their flours. Potato cultivars with lower mealiness scores, loosely packed cell arrangement, with comparatively large‐size cells and thinner cell walls showed lower values of textural parameters for both raw and cooked potatoes. This information may prove useful for the selection of potato cultivars with desirable textural and flour‐making properties for specific end‐uses. Copyright © 2005 Society of Chemical Industry     

Quality and nutritional value of strawberry fruit under long term salt stress

Modifications of fruit quality, in response to a long-term salt stress of four months, were studied in two strawberry cultivars differing in their sensitivity to salinity. The sensitive cv. Elsanta and the less sensitive cv. Korona were treated during two vegetation seasons with 0, 40 or 80 mmol NaCl/l in the nutrient solution. While mean fruit weight decreased, dry matter and contents of total soluble carbohydrates, as well as sweetness index of fruits, remained constant. Salt stress in both cultivars increased the antioxidant capacity, antioxidants pools (ascorbic acid, anthocyanins, superoxide dismutase) and selected minerals such as Na⁺, Cl⁻, K⁺, N, P and Zn²⁺, as well as lipid peroxidation. Furthermore, salt stress increased the contents of free and essential amino acids, especially in cv. Elsanta. The more tolerant cv. Korona was characterized by an increase of reduced glutathione and a better fruit taste. In salt-stressed fruits of cv. Elsanta, taste was significantly impaired.     

贮藏条件对全营养乳剂型特医食品品质特性和稳定性影响

目的 探讨贮藏条件对全营养乳剂型特医食品的品质特性和稳定性的影响.方法 按照GB 29922—2013《特殊医学用途配方食品通则》要求,制备全营养乳剂型特医食品,考察其在不同温度(4、25、45°C)以及有无光照(25°C)等条件下品质特性和稳定性指标变化.结果 温度对乳液品质特性和稳定性的影响显著,45°C贮藏30 ...     

Modeling changes in rheological properties of potatoes during storage under constant and variable conditions

The changes in rheological properties of potatoes stored at 5, 15, 25 °C and variable (fluctuating) temperature for 16 or 26 weeks were evaluated in terms of elasticity and viscosity parameters using axial compression and creep tests. Cylindrical test specimens (15 mm diameter and 30 mm long) were used. A third-degree polynomial best fitted the force-deformation curves in axial compression test (R²=0.98-0.99) whereas a four-element (Burgers) mechanical model adequately described the creep response of potatoes (R²=0.95-0.99). The tangent modulus of elasticity in axial compression and elasticity and viscosity parameters in creep tests in general decreased significantly (P<0.05) with increase in storage time both under constant and variable storage conditions. The changes in rheological properties of potatoes stored under constant storage condition were sufficiently described by a modified exponential model (R²=0.89-0.96) except for the viscosity parameter of the Maxwell component of the four-element model. The logarithm of degradation rate constant, k, and the constant, n, were linearly related to storage temperature. For the variable storage condition, a bulk mean temperature (T_bm) was calculated to account for a series combination of storage time and temperature to which the potatoes were subjected. The changes in rheological properties due to variable storage temperature were then described as a function of T_bm and storage time, t_s, using stepwise multiple regression. The result indicated that except the viscosity parameter of the Maxwell component of the four-element model, it was possible to describe the changes in rheological properties as a function of T_bm and t_s (R²=0.84-0.99).     

Influence of processing conditions on the physicochemical and sensory properties of sesame milk: A novel nutritional beverage

Production of sesame milk is one of the methods for increasing consumption of sesame as an excellent nutritional resource. The aim of this study was to examine the effects of sodium bicarbonate concentration in soaking water (0, 0.5 and 1 g/100 mL NaHCO₃), roasting temperature (0 and 145 °C) and blanching time (0, 15 and 30 min) on physicochemical and sensory properties of sesame milk. Changes promoted by these processing conditions were also evaluated via color analysis and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The processing parameters mainly affected pH, total solids, protein, fat, ash, lipoxygenase activity, stability, specific gravity, viscosity, color features and sensory properties. Sensory evaluation revealed that overall acceptability was higher in all treatments than the control. SDS-PAGE analysis showed that 7S globulins decreased by roasting and soaking while 11S globulins of sesame milk proteins increased by roasting. The optimum processing conditions were found to be soaking in water containing 0.5 g/100 mL NaHCO₃, blanching for 15 min and without any roasting when desirability function method was applied.     

不同采收期不同品种莲藕的营养品质变化规律及评价

目的 探究不同采收期不同品种莲藕的营养成分和活性成分的变化规律。方法 选取5个采收期的4个品种莲藕,测定蛋白质、淀粉等指标。采用主成分分析和聚类分析进行综合评价,并建立莲藕品质评价模型。结果 在采收期内,莲藕淀粉含量呈现先上升后下降再上升的趋势,可溶性糖的变化趋势与其相反;总酚含量整体呈现先上升后下降的趋势;蛋白质、膳食纤维等指标呈现不同的变化规律。主成分分析法提取出PC1、PC2、PC3 3个主成分因子,特征值依次为2.274、1.933、1.023,累积方差贡献率达87.170%。不溶性膳食纤维、可溶性膳食纤维、可溶性总糖、淀粉、总酚和总黄酮6个指标可以用来综合评价莲藕营养品质。综合评价发现, 9月采收的八月粉,10月的鄂莲6号,2月的鄂莲10号和鄂莲11号,营养品质较好,优于其他采收期。3月采收的4个品种莲藕的综合营养品质较低。结论 在采收期内, 4个品种莲藕的营养物质动态规律存在一定差异。基于主成分分析和聚类分析的分析方法能够科学评价不同采收期莲藕的综合营养品质,为莲藕育种、加工等提供支撑。     

Ultrasound-assisted extraction and modification of plant-based proteins: Impact on physicochemical,functional, and nutritional properties

Ultrasonication is a green technology that has recently received an enormous research attention for extraction of plant-based proteins and tailoring the functionalities of these ingredients. Ultrasonication is generally used as a pretreatment method in the conventional protein solubilization protocols because it can break the cell matrix to improve the extractability. The rate of protein extraction and increase in the extraction yields depend on operating conditions such as sonic energy density, time of sonication, the substrate to slurry ratio, agitation, and so on. Ultrasonication is also applied to modify the physical, structural, and functional properties of protein-based ingredients, besides simultaneous extraction and modifications. Significant changes that occur in protein physical properties due to sonication include size reduction, rheology, electrical conductivity, and zeta (ζ) potential. These changes are due to cavitation-induced shear leading to changes in secondary and tertiary structures, including protein aggregation and cross-linking due to oxidation. Physical and structural changes affect the resulting ingredient functionality and nutritional quality of protein. Changes in the functional properties, especially hydrophobicity, solubility, emulsion, and foaming, depend on the extent of ultrasound energy applied to the protein. This study aims to review major ultrasound process parameters and conditions for extraction and modification of plant proteins and their impact on protein structural changes and resulting physicochemical, functional, and nutritional properties.     

不同烹饪贮藏条件对营养配餐品质和安全性的影响

随着人们生活水平的提高以及学习与工作节奏的加快,越来越多的人们选择已经搭配好的营养餐食,以便节约时间,将更多精力投入到工作与学习中。针对不同烹饪贮藏条件对营养配餐品质与安全性的影响展开研究,以期为营养配餐未来发展提供宝贵的经验。     

平菇不同状态下营养成分分析比较与品质评价

目的测定并分析比较平菇在干、鲜两种状态下的营养成分及品质。方法依据国家标准,并采用原子吸收光谱仪、氨基酸自动分析仪等进行成分测定。结果鲜平菇的蛋白质含量高于干平菇,而总糖含量低于干平菇;不同状态下平菇的粗脂肪、粗多糖、粗纤维、矿物质元素含量相当;鲜平菇氨基酸总量为25.1 g/kg,比干平菇高出11.0 g/kg,但鲜、干状态中两者所含必需氨基酸占氨基酸总量分别为41.4%和41.1%,均符合FAO/WHO对理想蛋白质的要求。结论干、鲜状态平菇均可视为低脂肪高蛋白的食品源,在食药用方面具有良好开发潜能。     

Effect of ripeness at processing on fresh-cut 'Flor de Invierno' pears packaged under modified atmosphere conditions

The effects of ripeness at processing and packaging conditions on respiration, microbiological stability as well as colour and firmness of fresh-cut 'Flor de Invierno' pears were evaluated throughout storage. Although a 2.5-kPa O₂ + 7-kPa CO₂ atmosphere led to an inhibition of ethylene synthesis and carbon dioxide production compared with non-modified atmosphere packaging, the more advanced the ripeness stage at processing, the higher the physiological activity and thus, the higher production of carbon dioxide, ethylene and ethanol. A 2.5-kPa O₂ + 7-kPa CO₂ atmosphere inhibited bacterial growth, yeast and mould proliferation in mature-green pears but fast microbial growth was observed especially on ripe pears, under both packaging conditions. In conclusion, the shelf-life of ripe pears was reduced by increased respiration response to processing and accelerated microbial spoilage. Instead, pears processed in a partially ripe stage were suitable for conservation while gathering desired sensory attributes. Therefore, for commercial purposes, a shelf-life of 10 days was suggested for partially ripe fresh-cut pears packaged under a 2.5-kPa O₂ + 7-kPa CO₂ atmosphere.     

Effect of freezing/thawing conditions and long‐term frozen storage on the quality of mashed potatoes

The effects of freezing temperature (−80, −40 or −24 °C) and thawing mode (microwave or overnight at 4 °C) on quality parameters of mashed potatoes made from tubers (cv Kennebec) and from potato flakes were examined, as was the effect of long‐term frozen storage on the quality of mashed potatoes. Mashed potatoes were tested for texture profile analysis (TPA) and cone penetration, oscillatory and steady rheometry, colour, dry matter, Brix and sensory analyses. In natural mashed potatoes, TPA hardness and oscillatory parameters showed that processing resulted in a softer product than the fresh control. The parameters were lower in the samples thawed at 4 °C than in those thawed by microwave at all the freezing temperatures used, which may be ascribed to gelatinisation of the starch released from damaged cells. Differences from the freshly prepared product decreased when the samples were frozen at −80 °C and thawed by microwave. No difference was found in sensory acceptability between samples frozen at −80 and −40 °C, which probably reflects the panellists' mixed preferences for air‐thawed versus microwave‐thawed samples. Increasing the time in frozen storage led to a natural mash with a firmer texture, higher L*/b* value and Brix; nonetheless, panellists found the samples at 0, 3 and 12 months of frozen storage equally acceptable. In commercial mash, penetration and oscillatory parameters showed that processing made for a firmer product than the fresh control, probably owing to retrogradation of gelatinised starch. Thawing mode had a significant effect on parameters, which were lower in the samples thawed at 4 °C. The structure and quality of commercial mash was more detrimentally affected by freezing and, therefore, we would not recommend either freezing or frozen storage of this mashed potato in the used conditions. Natural mash made from Kennebec potatoes should be frozen quickly and thawed by microwave in the conditions described to obtain a product more similar to that freshly made. If the samples are frozen by air blasting at −40 °C, the product can withstand frozen storage for one year. Copyright © 2005 Society of Chemical Industry