Physicochemical properties of dry matter and starch from potatoes grown in Canada

In this study dry matter and starch were isolated from three potato cultivars (AC Stempede Russet, Russet Burbank and Karnico) grown at two locations (Fredericton and Benton) in New Brunswick, Canada. The chemical composition including total starch, dietary fibre, free glucose and protein content in potato dry matter and apparent amylose and total phosphorus content in potato starch were determined. Differential scanning calorimetry (DSC) was used to determine the thermal properties of gelatinization and retrogradation of potato dry matter and starch. The pasting properties of potato dry matter and starch were investigated by rapid visco analyzer (RVA). The resistant starch measurement method was employed to evaluate the digestibility in vitro of native and gelatinized potato starch. Molecular characteristics including chain length and chain length distribution of potato starch were also analyzed using high performance anion exchange chromatography (HPAEC). The analytical results suggest that differences in chemical composition and molecular chain length of potato starch may contribute to different functional properties of potato dry matter and starch of individual cultivars.     

不同品种马铃薯的氨基酸营养价值评价

试验收集了国内广泛种植且产量较高的29个马铃薯品种,应用模糊识别法和氨基酸比值系数氨基酸比值系数分等指标全面评价了不同品种马铃薯氨基酸的营养价值,并利用系统聚类法对29个品种氨基酸营养价值进行分类,筛选出氨基酸营养价值最高的6个马铃薯品种,分别为LBr-25、青薯168、高原号、俄8、渝马铃薯1号和Shepody。显著性分析结果显示系统聚类结果可靠,对保证马铃薯营养价值全面发及品种的合理利用具有一定的指导意义。     

Effect of cultivar,location and year on total starch,amylose, phosphorus content and starch grain size of high starch potato cultivars for food and industrial processing

In recent time the interest of industry increases particularly in processing and use of potato high amylopectin (AMP) starches. Therefore the plant breeders effort to obtain “waxy” potato cultivars with low amylose (AMS) content. In this four-year study sixteen potato cultivars grown on five experimental locations were evaluated on the percentage of AMS/AMP by enzymatic method, starch content by the underwater weight method, phosphorus (P) content in starch digests spectrophotometrically, and starch granule size determined by laser diffraction method. Between enzymatic and iodine–potassium iodide method good correlation has been revealed (r = 0.71). The correlation analysis between AMS and P levels showed a clear negative correlation. For all measured parameters (starch, AMS, P, starch granule size) significant impact of cultivar has been determined. Location and year have lower, but significant impact. No statistically significant effect of year on AMS has been found. The cultivar Amado distinguished with the highest AMP and P contents and the cultivar Westamyl showed all positive values interesting for growers and processors.     

Genetic and environmental effects on levels of glycoalkaloids in cultivars of potato (Solanum tuberosum L.)

Glycoalkaloids were assayed in fifty-five potato cultivars, fifty-four breeding lines and one other species (S. stolonifer). The total glycoalkaloid content ranged from 16·3 μg/g FW for Alpha to 317·0 μg/g FW for Berita, with most values lying between 35 and 65 μg/g. The α-solanine content, as a percentage of total glycoalkaloids, ranged from 28·3% for Avenir to 57·0% for H42, with the majority of values lying between 38% and 46% α-solanine. There was a highly significant correlation between high total glycoalkaloid content and per cent α-solanine (P < 1%). The presence of β₂-chaconine was also related in a highly significant way to high total glycoalkaloid content. Potatoes grown at Yanco (hot, dry, inland climate) contained more glycoalkaloids (～60%) than when grown at Glen Innes (cooler, high altitude climate). However, there was no significant difference between total and relative glycoalkaloid levels of cultivars grown at Glen Innes and Healesville (coastal, temperate climate). A significantly higher per cent α-solanine content, but not total glycoalkaloid content, was observed for potatoes grown in the second year at Glen Innes.     

In vitro digestibility of starch in cooked potatoes as affected by guar gum: Microstructural and rheological characteristics

Potatoes from different New Zealand cultivars (Nadine, Moonlight, Red Rascal, Agria) were analysed for starch digestibility in vitro (under simulated gastric and small intestinal conditions). The extent of starch hydrolysis (%) for all the potato cultivars ranged between 85% and 95% at the end of in vitro digestion. Nadine potatoes, which were waxy in texture, showed higher starch hydrolysis (%) whereas these levels did not differ significantly among the other three cultivars. Confocal laser scanning microscopy and scanning electron microscopy were performed on the digests in order to study the microstructural changes occurring during digestion in cooked potatoes. The micrographs clearly showed that starch was quickly hydrolysed by the enzymes present in simulated intestinal fluid (SIF) whereas the cell walls remained intact during simulated digestion process. Addition of guar gum (0.5%) to cooked potatoes reduced their starch hydrolysis (%) by ∼15% during the in vitro digestion. Online viscosity measurements were also performed on the cooked potatoes during simulated small intestinal digestion using a dynamic rheometer. Cooked potato viscosity dropped considerably upon the action of enzymes from SIF on starch as the digestion progressed. The presence of 0.5% guar gum facilitated the cooked potato matrix to maintain viscosity similar to undigested cooked potato sample throughout the in vitro digestion, which might have resulted in lower starch hydrolysis (%).     

Studies on the morphological,thermal and rheological properties of starch separated from some Indian potato cultivars

The starches separated from five different Indian potato cultivars (Kufri Chandermukhi, Kufri Badshah, Kufri Jyoti, Kufri Sindhuri and S1) were investigated for morphological, thermal, rheological, turbidity and water-binding properties. The starch separated from all the five potato cultivars had a granule size ranging between 15–20 μm and 20–45 μm. The shape of starch granules varied from oval to irregular or cuboidal. Starch isolated from cv. Kufri Badshah had largest irregular or cubiodal granules while starch from cv. Kufri Chandermukhi had small and oval granules. The transition temperatures and enthalpy of gelatinization (ΔH_gel) were determined using differential scanning calorimetry (DSC). The enthalpy of retrogradation (ΔH_ret) of gelatinized starch was also determined after 14 days of storage at 4°C using DSC. Kufri Chandermukhi starch showed the lowest ΔH_gel and ΔH_ret while Kufri Badshah starch showed the highest values. ΔH_gel and ΔH_ret values of 12.55 J/g and 6.42J/g, respectively, for Kufri Chandermukhi starch against 13.85 J/g and 8.61 J/g, respectively, for Kufri Bhadshah starch were observed. Rheological properties of starches from different potato cultivars, measured using the Dynamic Rheometer during heating and cooling, also differed significantly. The starch from cv. Kufri Badshah showed the highest peak G′ and G″ and lowest tan δ. The starches having higher peak G′(G′ at gelatinization temperature) showed higher breakdown in G′ and vice versa. The turbidity of gelatinized aqueous starch suspensions from all potato cultivars increased with increase in storage period. Starches with low water binding capacity had higher G′ and G″ and lower tan δ values.     

Parenchyma cell microstructure and textural characteristics of raw and cooked potatoes

Cooking, microstructural and textural characteristics from four New Zealand potato cultivars (Agria, Nadine, Moonlight, and Red Rascal) were studied. Potatoes from the waxy cultivar, Nadine, showed lowest dry matter and starch content and also had highest cooking time compared to the other cultivars. The total colour difference, ΔE, indicative of browning and darkening during storage (for 1 h) of the peeled potatoes was observed to be highest for Red Rascal, followed by Nadine and was lowest for Agria. Light (LM) and confocal scanning electron (CSLM) micrographs revealed Moonlight and Red Rascal raw potato parenchyma cellular structure to be well integrated, showing compact hexagonal cells. Raw tubers from these cultivars also exhibited higher hardness and cohesiveness, as observed using texture profile analysis (TPA). Moonlight potato parenchyma retained cell wall outline after cooking and its cells were observed to be completely filled with gelatinised starch matrix, whereas the cellular structure of Nadine potato parenchyma was completely disintegrated after cooking. TPA results of cooked potatoes agreed well with these microstructural observations, with Moonlight cooked potatoes showing highest cohesiveness and hardness. The cell wall of parenchyma cells was observed to degrade partially upon cooking of potatoes, resulting in loosening of the cell wall microfibrils, as observed using transmission electron microscopy (TEM) of a selected potato cultivar. Also, the cell wall decreased in thickness after cooking. The remains of the primary cell wall along with some electron dense granular structures were observed floating in the cytoplasmic starchy matrix in potato tuber parenchyma cells.     

GLYCOALKALOID CONTENT OF NEWFOUNDLAND GROWN POTATO TUBERS AND POTATO WART TISSUE

Eight cultivars of potato tubers grown in Newfoundland were examined for total glycoalkaloids (TGA) at harvest and after 3, 6, 9 or 12 days exposure to 150 footcandles light. Freshly harvested tubers had TGA ranging from 0.9 to 15.4 mg/100 g of total tuber tissue. TGA increased as a result of long term light exposure in all cases; however, those cultivars surface-pigmented with red or blue anthocyanins were less responsive to light induction. TGA in light exposed tubers ranged from 52–71 mg/100 g for white cultivars, 26–46 mg/100 g for red varieties, and 23–40 mg/100 g for those pigmented with blue anthocyanins. Healthy tubers from plants afflicted with potato wart did not show abnormally high TGA; however, healthy cankers contained as high as 170 mg/100 g. Greening or decomposition of wart tissue was associated with a decline in TGA. Thin-layer chromatography revealed α-solanine and α-chanconine were the principal components in TGA extracts of both tubers and wart tissue.     

Bioactive components in forced sweet cherry fruit (Prunus avium L.), antioxidative capacity and allergenic potential as dependent on cultivation under cover

Five early maturing varieties of Prunus avium L. on dwarfing rootstock were forced at Bonn, Germany in spring under transparent plastic cover without additional heating to ripen at a time before field-grown German fruit become available, with better fruit quality than imported sweet cherries; trees grown outside without cover served as control. The cover reduced the incident radiation by up to 54% PAR, UV by up to 22% UV-A and UV-B up to 2% and increased day temperature indoors. Fruit were as firm in the early varieties grown under cover as those in the field and slightly softer than in the late harvesting cultivars. Sugar content was slightly less in four of the five varieties; no differences in acidity and sugar/acid ratio as a taste indicator were found. Fruits were up to 3 mm larger when grown under cover in cvs. ‘Burlat’ and ‘Souvenir’, but no differences were observed in cvs. ‘Earlise’ and ‘Prime Giant’. Fruit of three cultivars, ‘Burlat’, ‘Samba’ and ‘Prime Giant’ can be classified as premium quality with 28 mm–30 mm diameter, when grown under cover. Overall, all cherry fruit were of the market, i.e. consumer- preferred, dark red colouration in line with enhanced anthocyanin contents. In two cultivars, the cover induced healthier fruit. Antioxidative capacity was larger in cv. ‘Samba’, while ascorbic acid (Vitamin C) was increased in cv. ‘Souvenir’; phenols were enhanced in all cultivars and attributed to heat stress. Allergenic protein (Pru av 1) in cherry fruits of both cultivation types were below the detection level at harvest time, indicating that cultivation under cover had no adverse effects on this particular health component.Overall, forcing successfully resulted in 2 weeks earlier ripening, thereby providing the first fresh and healthy (low allergen, high phenolic compounds and high anthocyanin) German cherries of high fruit quality on the market in spring.     

西北旱区不同品种马铃薯薯饼加工品质特性分析

为研究不同品种马铃薯与薯饼品质特性之间的关系,以适宜西北旱区栽培的13个马铃薯鲜薯为原料制备马铃薯薯饼,并对薯饼的感官和TPA进行了分析和比较,结果表明,不同马铃薯品种对加工薯饼的品质特性具有显著影响(p<0.05),不同品种马铃薯淀粉含量、蛋白质含量与马铃薯薯饼的硬度、弹性、胶着性及咀嚼性呈极显著正相关(p<0.01),而不同马铃薯品种淀粉含量、粗蛋白含量与马铃薯薯饼色泽无显著相关性(p>0.05);综合评价感官和TPA,供试的13个品种中,陇薯7号、陇薯8号、中薯18号和新品系LY08104-12的表现较好,制得的马铃薯薯饼感官品质较好,硬度适中,口感酥软,质构品质也较优。该结论可为不同马铃薯品种在薯制品加工适宜性方面提供一定的理论参考。     

Impact of selected factors – Cultivar,storage, cooking and baking on the content of anthocyanins in coloured-flesh potatoes

The impact of selected factors – cultivar, storage, cooking and baking on the content of total anthocyanins (TAC) in coloured-flesh potato cultivars has been studied. TAC ranged from 248.5 to 2257.8 mg kg⁻¹ dry matter (DM). TAC difference between cultivars was statistically significant. Cold storage (4 °C) influenced TAC differentially. In the Violette and Highland Burgundy Red cultivars TAC increased by 18.5% and 12.1% respectively, and in the Valfi cultivar it decreased by 33.9%. Baking increased TAC 3.34 times whereas cooking in boiled water increased it 4.22 times. Correlation between antioxidant activity (AOA) and TAC (r² = 0.659) has been found. The Violette, Vitelotte and Highland Burgundy Red cultivars with the highest TAC showed high AOA and the Shetland Black cultivar and the cultivars Salad Blue and Blue Congo with a “marbled” texture showed the lowest TAC and AOA. Individual anthocyanidins are fingerprints of colour-fleshed potato cultivars.     

不同品种马铃薯对马铃薯-小麦复合馒头品质特性的影响

本文以22个品种的新鲜马铃薯为原料制备马铃薯全粉,并对马铃薯全粉的基本成分进行了分析和比较;然后以22个不同品种的马铃薯全粉为原料制作马铃薯-小麦复合馒头(马铃薯全粉:小麦粉=3:7),并对其比体积、高径比、气孔结构和质构特性进行了分析和比较。结果表明,不同品种马铃薯-小麦复合馒头的比体积、高径比、气孔特性和质构特性存在显著差异性(p0.05)。高径比和比体积均较高的品种是紫花白、夏波蒂、陇薯6号、陇薯7号、中薯2号;气孔密度和气孔表面积分率都较高的品种是一点红、青薯9号、大西洋;硬度和咀嚼性都较好的品种是一点红、费乌瑞它、青薯6号、青薯9号、大西洋。综合考虑馒头的感官和物理特性,一点红、青薯9号和大西洋3个品种比较适合替代小麦粉,制得体积较为理想、硬度较低、气孔结构较好的馒头。     

Biofortified,selenium enriched,fruit and cladode from three Opuntia Cactus pear cultivars grown on agricultural drainage sediment for use in nutraceutical foods

Three different cultivars of drought, salt and boron (B) tolerant Opuntia ficus indica (Cactus pear) were grown in poor-quality agricultural drainage sediment high in salt, B and selenium (Se) that originated from the Westside San Joaquin Valley. Nutritional contents were then measured in these Cactus pear fruit (purple, red, or orange-coloured), and vegetative cladodes (modified stem-like leaves) compared to the same cultivars grown adjacent on a low saline sandy loam soil. After harvesting fruit and cladodes, the mineral nutrients, chemical speciation of Se, total phenolics, vitamin C and antioxidant status were analyzed. The results demonstrated positive nutritional changes in both cladodes and fruit within the Cactus pear cultivars when grown on agricultural drainage sediment compared to those grown on normal soil. Under these conditions Cactus pear plants contained nutraceutical qualities and represent a useful anticarcinogenic Se-enriched chemotherapeutic food crop for providing advanced dietary seleno-pharmacology in order to help fight human diseases.     

Development and characterization of extruded snacks from New Zealand Taewa (Maori potato) flours

Crispy extruded snacks were prepared by mixing ungelatinized dried potato flours from four different Taewa cultivars and a modern potato cultivar with corn flour at two different ratios (25:75; 50:50), and their quality characteristics studied. All of the potato flours showed differences in colour, dry matter content, starch content and pasting characteristics. Among the extrudates prepared with 25% potato flours, Huakaroro snacks showed an L¹ value of 51.71, whereas pure corn flour snacks had the highest L¹ value of 61.22. The b¹ at both levels of potato flour incorporation were lowest for Tutaekuri snacks. The microstructural characteristics of the extrudates such as cell structure and cell wall thickness changed considerably when potato flour was incorporated (50%) in the extruder feed. Moemoe, Tutaekuri and 100% corn flour snacks had the highest toughness, whereas the highest crispness was observed for the Huakaroro snacks. Lower and higher cold peak viscosities of 91 and 597 cP were observed for corn and Tutaekuri extrudates (in powdered form), respectively. The extrudates with 50% potato flour had higher breakdown and lower final viscosity than those containing 25% flour. The peak G′ values were highest for 100% corn, Moemoe and Karuparera snack pastes.     

<Emphasis Type="Italic">Sous</Emphasis><Emphasis Type="Italic">Vide</Emphasis> Processing as an Alternative to Common Cooking Treatments: Impact on the Starch Profile,Color, and Shear Force of Potato (<Emphasis Type="Italic">Solanum tuberosum</Emphasis> L.)

This study aimed to assess the effect of sous vide cooking on the total and resistant starch content, color, and shear force in three potato cultivars (Agria, Agata, and Carrera). Potato strips were also cooked by three common treatments (boiling, frying, and microwaving) to evaluate the differences between the methods. According to principal component analysis (PCA), sous vide-processed cv. Agria and Agata potato strips were grouped with boiled samples, in contrast, cv. Carrera sous vide samples were grouped with microwaved samples. Higher water losses were associated with microwaved potatoes due to the diffusion of water inside the tuber. In addition, a significant decrease in shear force was obtained after microwaving and sous vide cooking (p < 0.05) irrespective of the treatment strength. The three cultivars became less bright, and the intensity of the color decreased; however, variations in the cook value (C ₁₀₀, min) between treatments did not affect the lightness and hue angle. Regardless of the initial value of resistant starch and the intensity of the cooking process, all of the cultivars reached a final content of less than 5%. From our results, in-pack sterilization may be considered for application in the food industry as a technology that has a similar impact to conventional cooking treatments used on potato products.     

Comparison of functional components in various sweet potato leaves and stalks

The functional components of leaves and stalks from 14 sweet potato cultivars were investigated by determining lutein, β-carotene, chlorophyll, tannin and phenolic acid contents. It was found that the contents of the functional components in different cultivars differ significantly (p<0.05). Lutein, β-carotene and total chlorophyll contents were high in leaves and ranged from 19.01–28.85, 35.21–52.01 and 440.9–712.2 mg/100 g, respectively. The tannin and total phenolic acid contents of sweet potato leaves ranged from 2,280–4,460 and 2,640.2–4,200.9 mg/100 g, respectively. Significant correlations have been observed among cultivar, lutein, β-carotene, chlorophyll, and other antioxidants. The leaves of Healthymi cultivar contained the highest level of lutein, β-carotene and total chlorophyll, and Geonpungmi cultivar contained the highest level of the other antioxidant, among the all cultivars examined. Sweet potato leaves and stalks contain abundant functional components that make them potentially useful as fresh vegetables or processed foods.     

Some properties of potatoes and their starches II. Morphological,thermal and rheological properties of starches

The physico-chemical, morphological, thermal and rheological properties of the starches separated from different potato cultivars (Kufri Jyoti, Kufri Badshah and Pukhraj) were studied. The starches separated from the mealier cultivars (Kufri Jyoti and Kufri Badshah) showed lower transition temperatures (T_o; T_p and T_c), peak height indices (PHI), and higher gelatinization temperature range (R) and enthalpies of gelatinization (ΔH_gel) than the starch from the least mealy cultivar (Pukhraj). Swelling power, solubility, amylose content and transmittance values were observed to be higher for Kufri Jyoti and Kufri Badshah potato starches, while turbidity values were lower for these starches. The rheological properties of starches, measured using a dynamic rheometer, showed significant variation in the peak G′, G″ and peak tan δ values. Kufri Badshah and Kufri Jyoti starches showed higher peak G′, G″ and lower peak tan δ values than Pukhraj starch during heating and cooling cycles. Kufri Jyoti and Kufri Badshah starches showed higher breakdown in G′ than starch from the Pukhraj potato cultivar. The large-sized granules of the starches from Kufri Badshah and Kufri Jyoti appeared to be associated with higher values of peak G′ and G″ and consistency coefficient. Starch from the least mealy cultivar (Pukhraj) showed higher retrogradation, which increased progressively during storage at 4 °C for 120 h.     

Physical and thermal properties of three sweetpotato cultivars (Ipomoea Batatas L.)

Physical and thermal properties of three commonly grown sweetpotato cultivars were evaluated. Density, specific heat, thermal conductivity, and respiration rate were determined for ‘Beauregard’, ‘Hernandez’, and ‘Jewel’ varieties. In addition, respiration heat and thermal diffusivity were calculated for these cultivars. Uncured and cured sweet potato were evaluated and held under controlled storage conditions. Postharvest treatment and cultivar differences had minor effects on the density, specific heat, and thermal conductivity of sweetpotato. Respiration rate of the uncured and cured sweetpotato was evaluated at four temperatures: 15, 20, 25, and 30°C. Respiration rate and respiration heat for the cured sweetpotato was less than that of the uncured sweet potatoes. Results from this study will be instrumental in the design and optimization of sweetpotato curing and storage facilities and in the development of new quality indicators.     

Milling behavior of hulled barley and its thermal and pasting properties

Eight commonly grown Indian hulled barley cultivars were studied for their dehusking, pearling, physico-chemical, β-glucan, pasting and thermal behavior. Milling of the hulled barley at 14% moisture significantly lowered the dehusking and pearling time as compared to milling at 10% moisture content. The extraction rate ranged from 55.05% to 62.35% and significantly (p < 0.05) differed among the cultivars. Particle size distribution of flours was significantly different among the cultivars with flour from RD-2552 and RD-2035 cultivars having the most even particle size distribution. The colour difference (ΔE) was not significantly different among cultivars. The extractable β-glucan content varied from 1.93% to 3.81% among the cultivars and was highest in PL-172. The final pasting viscosity was significantly different among cultivars while the pasting temperature did not vary significantly. The enthalpy (ΔH) of gelatinization of barley flour varied from 4.45 to 7.08 J/g and gelatinization temperature (T_p) varied from 64.23 to 66.26 °C.