Transformation of carbohydrate and nitrogen compounds in potato tubers during drying: Part 1—The influence of tritox applied in cultivation of potatoes upon transformations of carbohydrate and nitrogen compounds during potato drying

The influence of tritox on the concentrations of starch, saccharose, reducing sugars and nitrogen compounds, is investigated in fresh and dried potato tubers. Tritox hinders carbohydrate transformations and enhances nitrogenous transformations. These effects may be enzyme-mediated.     

Effect of chlorpropham (CIPC) on carbohydrate metabolism of potato tubers during storage

Two chipping cultivars, Snowden and Monona, with or without Chlorpropham (CIPC) application, were stored in darkness at 10–12 °C and approximately 95% humidity, following the 1997 growing season. Chip color, dry matter, and protein contents were monitored over 30 weeks of storage. Tuber concentrations of sucrose, reducing sugars, and major metabolites, as well as enzymes involved in glycolysis, oxidative pentose phosphate pathway, anaerobic and oxidative respiration were monitored during storage. Respiration, as measured by CO₂ production, was significantly (P⩽0.05) suppressed in CIPC-treated tubers. CIPC treatment had no significant (P>0.05) effect on chip color quality or tuber concentrations of protein, dry matter, sucrose, reducing sugars, or the assayed enzymes and metabolites of glycolysis (phosphofructokinases, NADH, ATP). The metabolite NADPH was higher in untreated tubers, consistent with its role in anabolic biosynthetic pathways involved in sprout production. Concentrations of ethanol and lactate, products of anaerobic respiration, were significantly (P⩽0.05) higher in the CIPC-treated Snowden tubers, relative to the untreated tubers.     

干燥工艺对甘薯淀粉回生率影响

以甘薯淀粉为原材料,以甘薯淀粉回生率为指标,研究常温、太阳晒、真空减压、干燥箱和微波干燥等不同干燥工艺对甘薯回生抗性淀粉生成率影响。结果表明,各干燥最佳工艺参数为:常温下大气温度为16℃～19℃、大气湿度为68%～80%时,老化后甘薯淀粉5 d达至恒重,回生率由3.5%提高到4.5%,提高28.5%;阳光照射下,大气温度为23℃～36℃、大气湿度为42%～74%时,老化后甘薯淀粉5 d达至恒重,回生率由3.5%提高到4.7%,提高34.2%;真空干燥箱温度为120℃、真空度为0.08 MPa时,甘薯淀粉回生率最大,为14.62%,比空白提高3.1倍;干燥箱温度为90℃时,甘薯淀粉回生率最大,为12.24%,比空白提高2.5倍;微波温度为45℃时,甘薯淀粉回生率最大,为7.12%,比空白提高1倍;相比之下,真空干燥有利于甘薯淀粉回生。     

Changes in some nitrogenous constituents of potato tubers during aerobic autolysis

Potato tubers of four cultivars were ground and allowed to undergo aerobic autolysis. Tubers were fractionated before and after autolysis, and distributions of dry matter, N and of free and bound amino acids measured. “Chemically available lysine” and chlorogenic acid were also determined. Extent of “enzymic browning” correlated with loss of free tyrosine but not with “chemically available lysine” content. This last may have been influenced by enzymic oxidation of chlorogenic acid. Losses of S-containing amino acids were observed. Free 4-aminobutyric acid increased and free glutamic acid decreased, suggesting α-decarboxylation of the latter.     

Change in dielectric properties of sweet potato during microwave drying

Food Science and Biotechnology - Sweet potato slices and strips (thickness of 6 and 9 mm, respectively) as single layer were dried at different microwave power levels (90 W to...     

Light exposure and wounding: synergistic effects on steroidal glycoalkaloid accumulation in potato tubers during storage

Potato tubers contain undesirable steroidal glycoalkaloids (SGAs), which have evoked global concern in terms of feed and food safety due to their toxic effects in humans. The cultivar Unica was exposed to a combination of light and wounding. SGA content among different tissues was analysed. Our results showed that SGA contents of tubers subjected to light was higher than that of intact tubers stored in darkness, and SGA content in the skin varied with time; however, SGA content in the flesh remained stable at a relatively low level. SGA content in the wound was higher than that of intact tubers. Importantly, light and wounding were shown to have synergistic effects on SGA content in the tuber, which only influenced SGA content within approximately 3 mm of the wound surface. Our study provides a theoretical basis for the reasonable and safe consumption of potatoes.     

Proximal composition,bioactive compounds and biorefinery approach in potato tubers of Solanum tuberosum Group Phureja: a review

Potato tubers of Group Phureja have a great relevance in terms of production and consumer acceptance in the Andean countries. However, its proximal characteristics, nutritional value and bioactive compounds have been scarcely known. For the first time, this work aims to give an overview on tubers of Group Phureja characteristics, including research works from 1993 to 2019. When analysing the micronutrients and bioactive analytes, sodium, niacin and carotenoid contents are higher as compared to those of the Group Tuberosum. Likewise, the application of a biorefinery approach for the valorisation of Group Phureja wastes was proposed. These wastes may come from tubers that fail to meet quality parameters or by processing potato products. The possibility of obtaining useful compounds for the food, feed, materials, energy and chemical industries is described. The strategy of valorisation of wastes was focused on the production of starch and proteins, previously reported with important technological properties.     

Effect of antiviral genetical modification on softening of potato tubers during cooking

An investigation into the influence of genetical modification on potato tubers should include also an estimation of their technological usability. Potato tubers of 15 clones of cultivar Irga transformed with viral genome sequences in order to improve their resistance to a necrotic strain of potato virus Y (PVY^N) were examined. The effect of cooking on tissue texture, expressed by fracture stress (F) and strain (D), and elastic modulus (E) from a compression test, was investigated. Although the influence of the modification type appeared to be statistically significant but irregular in particular years of cultivation, a detailed statistical analysis (variance and discrimination analyses) did not confirm any repeatable nor statistically significant differences in F, D, and E over the three-years period of examinations. While the effect of cultivation year was unmistakable, the order of F, D, and E values for particular clones was not constant in the successive years. The lack of stable tendencies in average values of the mechanical parameters for both groups and subgroups of clones representing the same modification model was also found. The statistical analysis of the variability of mechanical parameters of raw and heat-treated potatoes measured during the three successive years enabled classifying Irga and its genetically-modified clones as similar and did not allow to distinguish clones of the quickest softening.     

Evolution of antioxidant compounds in lime residues during drying

This work aimed at studying the effects of pretreatment, namely, hot water blanching, and hot air-drying (60–120 °C) on the evolutions of vitamin C, phenolic compounds, nomilin and limonin, which are potential bioactive compounds in lime residues during drying. Blanching was found to decrease both the antioxidant contents and activities of the residues due to thermal degradation and loss with the blanched water. During drying, nomilin and limonin contents first increased, probably due to the remaining enzyme activity after blanching. After this period, the amounts of both nomilin and limonin dropped rapidly, due to thermal degradation. Product temperature was found to be a major factor controlling the changes of limonoids and there was no direct correlation between the moisture change during drying and limonoid contents. During degradation of vitamin C and phenolic compounds, the amounts of both substances decreased as the product temperature increased and the moisture content decreased during drying. The amount of phenolic compounds correlated well with the total antioxidant activity and phenolic compounds were found to be a major contributor to antioxidant activity of the product.     

1-甲基环丙烯处理对窖藏马铃薯的保鲜效果

以黑龙江省绥化市品种为黄麻子的马铃薯为试材,采用不同浓度1-甲基环丙烯（1-MCP）处理,研究窖藏马铃薯采后生理、贮藏品质及发芽率。结果表明:1.0μL/L 1-MCP处理,能有效减缓块茎淀粉的降解、抑制VC和总酚含量的下降及还原糖的上升,能显著降低块茎的呼吸速率,抑制与块茎衰老相关的PPO和POD活性的快速升高。在此处理方式下,贮藏到180d,块茎并未发芽,保鲜效果良好。      

Lipids of potato tubers. I. Lipid and fatty acid composition of tubers from different varieties of potato

Tubers from 23 varieties of potato were obtained at harvest and analysed for total lipid content, lipid composition and distribution of component fatty acids. The total lipid content was similar for all varieties (approx. 0.1% of the fresh weight) and no significant differences were observed between varieties in the individual lipid components. The polyunsaturated fatty acids, i.e. linoleic and linolenic acids, represented 51 to 60 and 13 to 24%, respectively, of the total fatty acids. An inverse relationship between linoleic acid and linolenic acid was observed resulting in a very similar proportion of the combined polyunsaturated fatty acids for all varieties (70 to 76% of total fatty acids). The results are discussed in relation to the role of lipids in the potato tuber.     

The nitrogen content of potato (Solanum tuberosum L.) tubers in relation to nitrogen application—the effect on amino acid composition and yields

The effect of nitrogen application on the nitrogen content and yield of amino acids from potato tubers was studied in one experiment in 1983 and two in 1984. Increasing fertiliser N over the range 0–250 kg ha^?1 raised tuber nitrogen concentrations from 0.68–0.81 to 1.27–1.49% DM. Applying half the fertiliser on the seedbed and half at tuber initiation did not increase tuber nitrogen concentrations compared with a single broadcast application at planting. Increasing tuber nitrogen concentrations had little effect upon the proportion recovered in amides or the different amino acids. Yields of some nutritionally essential amino acids were, therefore, substantially increased up to a maximum of 256 kg ha^?1 in 1982 and 308 and 384 kg ha^?1 in 1984 at the highest fertiliser level. These yields were significantly higher (P<0.01) than those found with the nitrogen application rate optimal for tuber dry matter production (213, 195 and 331 kg N ha^?1, respectively) in the same experiments. Methionine and cystine were the limiting essential amino acids. As the amount of each amino acid contained in a unit weight of fresh tuber increased with nitrogen supply, application of more nitrogen than is needed for maximal tuber dry matter production increased protein yields without decreasing the nutritional quality.     

Studies on nucleotides and related compounds in plants. II. An adenyl-cleaving enzyme system in potato tubers

Adenyl-cleaving activity was demonstrated in clarified potato juice. A stock freezedried enzyme preparation, obtained after (NH₄)₂SO₄ fractionation, hydrolysed adenosine and deoxyadenosine but had no effect on other possible nucleoside substrates including cytidine, deoxycytidine, guanosine, deoxyguanosine, inosine, hypoxanthosine, uridine and thymidine. The rate of adenine release for adenosine was some 60% of that for deoxyadenosine under the conditions of the digest. AMP, ADP, ATP and dAMP were all susceptible to hydrolysis releasing adenine. Evidence is produced to show that dephosphorylation is a necessary prerequisite to adenine release. The adenine nucleosidase has an optimum pH 4.1–4.6 and an apparent temperature optimum of 50 °C.     

葡萄果实成熟过程中含氮化合物的变化

本文通过对琼瑶浆、玫瑰香、赤霞珠、小白玫瑰4个葡萄品种在果实成熟过程中硝态氮、氨态氮、总氮含量的测定,探讨了葡萄果实成熟过程中不同氮化物的变化.结果表明:4个品种在果实成熟过程中果肉和种子中硝态氮、氨态氛、总氮含量呈逐渐升高的趋势,接近成熟时其含量趋于稳定;4个品种果实种子中的硝态氮、氨态氮、总氮含量均高于果肉中的含量.     

Improvement of water transport mechanisms during potato drying by applying ultrasound

BACKGROUND: The drying rate of vegetables is limited by internal moisture diffusion and convective transport mechanisms. The increase of drying air temperature leads to faster water mobility; however, it provokes quality loss in the product and presents a higher energy demand. Therefore, the search for new strategies to improve water mobility during convective drying constitutes a topic of relevant research. The aim of this work was to evaluate the use of power ultrasound to improve convective drying of potato and quantify the influence of the applied power in the water transport mechanisms. RESULTS: Drying kinetics of potato cubes were increased by the ultrasonic application. The influence of power ultrasound was dependent on the ultrasonic power (from 0 to 37 kW m^?3), the higher the applied power, the faster the drying kinetic. The diffusion model considering external resistance to mass transfer provided a good fit of drying kinetics. From modelling, it was observed a proportional and significant (P < 0.05) influence of the applied ultrasonic power on the identified kinetic parameters: effective moisture diffusivity and mass transfer coefficient. CONCLUSIONS: The ultrasonic application during drying represents an interesting alternative to traditional convective drying by shortening drying time, which may involve an energy saving concerning industrial applications. In addition, the ultrasonic effect in the water transport is based on mechanical phenomena with a low heating capacity, which is highly relevant for drying heat sensitive materials and also for obtaining high‐quality dry products. Copyright © 2011 Society of Chemical Industry     

前处理和干燥对甘薯全粉品质影响的研究进展

本文从甘薯全粉生产过程中的前处理和干燥两个方面对甘薯全粉品质的影响进行综述,对现代食品技术在生产甘薯全粉中存在的问题进行了探讨,以期为该领域的研究者提供理论参考.     

风鸡腌制和风干过程中挥发性成分的变化

采用顶空固相微萃取与气相色谱-质谱仪联用技术,以2,4,6-三甲基吡啶为内标,对风鸡腌制和风干过程中的挥发性成分进行定性和定量分析。结果表明:在原料和腌制阶段的样品中均分别检测到49种和48种风味化合物;在风干1、3和5d的样品中分别检测到44、55和48种风味化合物。这些成分可归类为:醇类、羧酸类、烃类、酮类、酯类、醛类和醚类化合物。风鸡经过腌制和风干之后,醇和烷烃类的种类大幅增加,而羧酸类、芳香类、酮类、醇类、酯类、烷烃类和醚类化合物的绝对含量明显增加。在腌制之后的样品中,苯乙烯、2,3-辛二酮、己醛、辛醛、壬醛、苯甲醛、肉桂醛、芳樟醇、桉树醇、甲酸异龙脑酯和茴香醚等对风鸡风味的形成贡献较大;在风干之后的样品中,主要挥发性风味物质包括:3-羟基-2-丁酮、肉桂醛、壬醛、苯甲醛、苯乙醛、芳樟醇、3-甲基-1-丁醇、桉树醇、甲酸异龙脑酯和茴香醚等。     

Indirect gas chromatographic determination of IPC and CIPC in potato tubers

A sensitive and reproducible method for the determination of the sprout-inhibitors IPC and CIPC in potatoes has been developed. Both substances were hydrolyzed in acidic medium and corresponding anilines were determined after acetylation by means of gas chromatography using flame ionization detector. The detection limit for both compounds was 0.01 mg · kg^?1.