The recovery of maleic hydrazide from processed potato products

Summary A method used for estimating extractable maleic hydrazide (MH) concentrations in fresh potato material, concentration range 5–17 mg kg⁻¹, was found not to be suitable for processed potato products (10–33% recoveries) although, boiling potato pieces enhanced recovery by 20%. Each step of the determination was examined and a modified procedure developed with particular emphasis on the extraction of MH from the dried potato matrix, and the quality of the HPLC column used. Potato slices and model systems based on filter papers plus additives were used. Recoveries from fried potato slices were 74±6%. Based on the effect of glucose in reducing extractable MH recoveries, it is suggested that the remainder of the MH (20–25%) is converted into a conjugated structure on reaction with dehydrated sugar (Diels-Alder reaction).     

Effect of Cooking and Processing on CIPC Residue Concentrations in Potatoes and Processed Potato Products

Residue concentrations of the sprout suppressant chlorpropham (or CIPC) were determined in raw and cooked potatoes and processed potato products, 48 h after CIPC aerosol treatment and after 30 days of subsequent storage at 4 or 12 °C. In the raw (uncooked) tuber, 48 h after CIPC treatment, the CIPC residue in the peel was 4.7 mg kg^-1, while in the peeled tuber it was 0.1 mg kg^-1. Boiling resulted in a decrease in residue concentration in the peel, but no significant differences in the residue concentration of the peeled tuber were observed. Pressure cooking resulted in a significantly increased residue concentration in the peel, but no significant change in the peeled tuber, whereas microwave cooking also did not increase the residue concentration in the peel significantly compared with that in raw tubers. Also the trend towards increases in residue concentration in microwave-cooked peeled tubers was not significant. The CIPC residue concentration detected in peeled tubers was 0.4–0.7 mg kg^-1 after boiling, 0.4–1.5 mg kg^-1 after pressure cooking and 0.4–3.8 mg kg^-1 after microwave cooking. The highest values were always found for tubers stored for 30 days at 4 °C. Processed products such as crisps, French fries, dehydrated sliced potatoes and starch contained different concentrations of CIPC residue, which was also detected in the cooking water and frying oil. The highest residue concentrations detected were 0.7, 4.7, 1.3 and 0.2 mg kg^-1 in crisps, French fries, dehydrated sliced potatoes and starch, respectively. The highest CIPC residue concentration observed in raw potatoes was much lower than the maximum residue level of 10 mg kg^-1 prescribed by the European Union.     

Effect of CIPC on Sprout Inhibition and Processing Quality of Potatoes Stored Under Traditional Storage Systems in India

Indigenous non-refrigerated methods like heaps and pits are used in India for short-term storage of potatoes (Solanum tuberosum L.) to avoid distress sale. Storing untreated potatoes generally results in high losses from sprouting, moisture loss and rotting. To reduce storage losses by inhibition of sprouting and to determine the suitability of stored potatoes for processing into crisps, a single spray application of a commercial formulation of 3-chlorophenyl carbamate (CIPC or chlorpropham) 50% a.i., (Oorja, United Phosphorus Limited, Mumbai, India) of CIPC (or chlorpropham) was tested on potatoes during storage from March to June under two traditional storage methods [heap (17–33 °C, 58–92% relative humidity (RH)) and pit (17–27 °C, 72–95% RH)] in 2 years [2005 up to 90 days of storage (DOS) and 2006 up to 105 DOS], using four cultivars and two rates of CIPC application (20 and 30 mg a.i. kg⁻¹ tubers). The two rates of application were comparably effective in reducing weight losses, sprouting and sprout growth in stored tubers, and the effect was more pronounced in pit storage than in heap storage. By contrast to untreated tubers, CIPC-treated potatoes remained turgid under the two storage methods and fetched market prices comparable to those for cold-stored (2–4 °C) potatoes after 105 days of storage. Reducing sugar concentrations in treated potatoes decreased during storage especially in 2006 when the initial reducing sugar concentration was higher than in 2005. Crisp colour improved only in 2005 after 90 DOS, but it deteriorated in 2006 during storage up to 105 DOS. Sucrose concentration increased tremendously during storage in 2 years. Only one cultivar (Kufri Chipsona-1) with low initial reducing sugar concentration and less sucrose accumulation during storage could produce acceptable colour crisps after storage in both years. The remaining three cultivars—with high initial reducing sugar concentration—were suitable for processing after storage in heap and pit in 2005, but not in 2006. Stored potatoes were safe for human consumption as the CIPC residue concentrations were far below the permissible level of 10 mg kg⁻¹ as prescribed by the European Union. Single spray application of CIPC (20 mg kg⁻¹ treatment) can effectively reduce storage losses in potatoes stored in traditional non-refrigerated methods of heap and pit and extend the storage life by 90 to 105 days.     

The effect of irrigation and nitrogen on powdery scab and yield of potatoes

Summary Powdery scab, caused by the fungusSpongospora subterranea, has developed in the Cappodocia region of Turkey because of changes in agronomic practices, such as excessive irrigation and nitrogen fertilizer use and growth of highly susceptible cultivars. The most suitable irrigation and nitrogen application levels were established to maintain powdery scab at minimum levels without affecting potato yield. Three irrigation levels were used in 1998 (673, 897, 1121 mm) and five in 1999 (329, 494, 658, 823, 987 mm). Nitrogen levels were applied 150, 300, 450, 600 kg N ha⁻¹. In 1998, least powdery scab occurred with 673 mm irrigation, which yielded 41 t ha⁻¹ potatoes. The lowest disease severity occurred in 1999 with 494 mm irrigation and 150 kg N ha⁻¹. At these levels, tuber yield was 34 t ha⁻¹ which was not significantly different from the highest yield measured. In 1999 and at two of the three irrigation levels inl998, nitrogen increased disease severity.     

Effect of two plant growth regulators on the yield and quality of russet burbank potatoes

Summary Foliar applications of ethephon (ETH) 300 g a.i. ha⁻¹; chlormequat chloride (CCC) 920 g a.i. ha⁻¹, with a second application of 230 g a.i. ha⁻¹ approximately 2 weeks later; and a mixture of the two (ETH/CCC) 156 g a.i. ethephon and 299 g a.i. chlormequat chloride ha⁻¹ were made to field-grown Russet Burbank potatoes in 1986, 1987 and 1989. All the treatments increased the number of tubers set and reduced the average tuber weight compared to the control resulting in a reduction in premium and marketable tubers, and an increase in small tubers. Differences were greatest for ETH and least for CCC. ETH and ETH/CCC decreased the specific gravity, increased the incidence of deformities, and decreased the incidence of tubers with hollow heart. The growth regulators did not affect fry colour.     

Effect of Cultivar, Year Grown, and Cropping System on the Content of Tocopherols and Tocotrienols in Grains of Hulled and Hulless Barley

In a three-year period (2000–2002) total tocols (tocopherols and tocotrienols), content of vitamin E and its isomers (α-, β+γ-, δ-tocopherols and tocotrienols) were assessed in grain of 13 barley genotypes. The highest content of tocols (60.3–67.6 mg kg⁻¹) and content of vitamin E (Vitamin E equivalent—18.0–20.1 mg kg⁻¹) were determined in the waxy varieties Wanubet, Wabet, and Washonubet. Standard varieties, i.e. of a malting type (Krona and Kompakt), had statistically significantly lower content of tocols (49.9 and 53.6 mg kg⁻¹) and vitamin E (15.7–16.1 mg kg⁻¹) compared to the waxy varieties. The hulless waxy variety Washonubet had statistically significantly higher total content of tocols (67.6 mg kg⁻¹) and α- tocotrienols isomer (42.1 mg kg⁻¹) versus all other genotypes in the set. Chemical treatment and fertilization statistically significantly increased the content of tocols (by 4.7 mg kg⁻¹), vitamin E (by 1.9 mg kg⁻¹), isomer α-tocopherol (by 0.9 mg kg⁻¹) and isomer α- tocotrienols (by 3.3 mg kg⁻¹). The average values of α-tocopherols and α-tocotrienols in the set were 6.7 mg kg⁻¹ and 29.7 mg kg⁻¹, respectively. Some of the reciprocal lines created by us from the malting and waxy varieties are suitable for food use for high contents of all tocopherols and α-tocotrienols.     

Influence of storage temperature on rate of potato tuber tissue infection caused byPhytophthora infestans (mont.) de bary estimated by digital image analysis

Summary Potato tubers were inoculated with two biotypes ofPhytophthora infestans then stored at 3,7, 10 and 15°C. Image analysis quantified average reflective intensity (ARI) of diseased tissue from cut surfaces of sample tubers. Tuber tissue infection and infection rate were measured by calculating Mean ARI of samples. Average tuber tissue infection and infection rate was minimal at 3°C (P.i.-US8 orP.i.-US1). Tuber tissue infection increased at temperatures >3°C, from 220 Mean ARI seven days after inoculation (dai) to 190–150 Mean ARI 50 dai (depending on cultivar and biotype ofP. infestans). Rate of tuber tissue infection caused byP.i.-US1 at 7°C was about zero in cv. Snowden but greater than −0.2 ARI day⁻¹ (cvs Russet Burbank and Superior). Rate of late blight infection in tuber tissue generally increased with temperature from −0.2 ARI day⁻¹ (at 7°C) in all cultivars to a maximum of −0.8 ARI day⁻¹ (10°C).     

Effect of sprout inhibitors on potato tubers (Solanum tuberosum L.) stored at ambient or reduced temperatures

Summary Single and combined applications of three sprout inhibitors, maleic hydrazide (MH), isopropyl 3-chlorophenylcarbamate (CIPC) and isopropyl phenylcarbamate (IPC) mixed with CIPC in a commercial formulation coded AMK (Tixit-C, Sandoz, S.A.E., Barcelona, Spain; 2.0% IPC +0.7% CIPC) were tested on potatoes stored from March to June under ambient conditions (20–30°C, 30–80% RH), and in a store with passive evaporative cooling (16–30°C, 75–95% RH). All treatments were more effective in reducing physiological losses, sprouting, and sprout growth in the cool than in the ambient store. AMK, CIPC and MH+AMK caused most sprout suppression. All treatments increased tuber rotting but there were no significant differences in numbers rotted by MH, MH+CIPC, CIPC (single treatment) and the untreated control. Nevertheless, the treatments can usefully extend storage life of potatoes under non-refrigerated conditions.     

Determination of thiabendazole residues in potatoes using high pressure liquid chromatography

Summary This paper describes a method for the extraction, purification and quantification by high pressure liquid chromatography using fluorimetric detection, of thiabendazole residues from potatoes. Bonded silica sorbent extraction columns (diol phase) are used for sample clean up, resulting in a rapid and accurate analysis. The average recovery was 93.8%±2.1%. Levels of about 0.0004μg of TBZ, equivalent to 0.033 mg kg⁻¹ in potatoes (on fresh weight basis), were readily detected from deliberately contaminted potatoes.     

The effect of chloride fertilization on blackspot susceptibility and other quality characteristics and on yield of potato

Summary Trials were carried out in two years on a sandy loam and on a heavy clay soil with two cultivars to examine the potential of chloride fertilization as a tool to reduce blackspot susceptibility of potatoes and to investigate other effects on yield and quality. Blackspot susceptibility was significantly reduced in cv. Marijke, but not in cv. Bintje as a result of increasing doses of applied chloride from 0 to 400 kg ha1. Dry matter concentration, assessed as under-water weight, was reduced by chloride in both cultivars at the two locations. Fry colour of French fries was improved by chloride. Applying 400 kg ha⁻¹ Cl⁻ to both soil types decreased net tuber yield >35 mm of cv. Bintje but not of cv. Marijke. Chloride caused slower emergence, retarded crop development and less stems per plant on the sandy loam soil but not on the heavy clay soil.     

Plant regeneration from tuber discs of potato (Solanum tuberosum L.) using 6-benzylaminopurine (BAP)

Summary Shoots, roots and callus were formed from tuber discs of potato, cultivar Désirée, when grown in vitro on the basal medium of Murashige & Skoog (1962) (MS) supplemented with 2,4-D and/or BAP. Callus was formed in MS medium with 1 mg l⁻¹ BAP plus 0.5 mg l⁻¹ 2,4-D, callus and roots were formed in MS with 1 mg l⁻¹ BAP plus more than 0.5 mg l⁻¹ 2,4-D and shoots were formed directly on tuber discs cultured on MS medium with 1 mg l⁻¹ BAP without the addition of 2,4-D. Nodules produced at the explant surface after the 4th week increased in size following subculture onto the same medium (MS+BAP alone), and 2 to 6 shoots developed from each nodule. After 9 weeks total time in culture, these shoots were excised and transferred as cuttings to MS medium without growth regulators, after which roots developed and plantlets were formed. A histological study of the explants at the sites of nodule formation indicated that the shoots developed from meristematic zones initiated within small outgrowths of tissue similar to those occuring in adventive organogenesis but the presence of shoot and root meristems associated with the same axis suggests the formation of somatic embryos.     

Yield and quality of Russet Burbank potato as influenced by interactions ofRhizoctonia,maleic hydrazide,and PCNB

Soil treatment with pentachloronitrobenzene (PCNB) at 22.4 kg/ha a.i. reduced symptoms of theRhizoctonia disease (Rhizoctonia solani Kühn) on potato (Solarium tuberosum L.) and resulted in significant increases in the numbers of stems and stolons. With disease control there was no effect on either total or U.S. #1 yield, but decreases of tuber size were evident and effects were observed on grade. Yield of malformed tubers was reduced by 35%, but this benefit was counteracted by a 41% increase of undersized tubers. Among U. S. 1’s, yield of non-size A’s (113 to 170 g) were increased by 22%, while tubers in optimum size ranges for french fries and bakers (> 284 g) were decreased by 24%. No effect was observed on carton sized tubers (170 to 369 g). Foliar sprays of maleic hydrazide (MH) applied on either of several dates (23 July, 2 Aug., 13 Aug.) at 3.4 kg/ha a.i. reduced total yield by 4.9 to 5.7%, but yields of U.S. #1 potatoes or sizes > 170 g were unaffected. Treatments with MH on either 23 July or 2 Aug. reduced yield of undersized potatoes by 23%. MH treatments did not interact with PCNB treatment to change either total yield or size, but adverse effects on U.S. #1 yields were indicated. MH treatments applied on either 2 Aug. or 13 Aug. reduced U.S. #1 yields among PCNB treated plots by 7 to 10%. MH reduced length/width ratios and, depending on date of application, increased specific gravity. PCNB did not influence tuber shape or specific gravity, but a significant reduction of standard deviations among length/width ratios indicated greater uniformity of shape with treatment.     

The degree of starch phosphorylation as influenced by phosphate deprivation of potato (Solanum tuberosum L.) plants

Summary The levels of starch phosphorylation in potato tubers were investigated in relation to fertilization with phosphorus (P) of field-grown and greenhouse-grown plants. The field-grown plants received 0, 15 or 30 kg P ha⁻¹. Starch from plants grown without P-fertilizer contained 15.6 nmol P (mg starch)⁻¹ whereas starch from plants grown with 30 kg P ha⁻¹ contained 20.6 nmol P (mg starch)⁻¹. The greenhouse-grown plants were cultured in inert media and received nutrient solutions containing 0, 3, 12 or 24 mg P l⁻¹, respectively. Plants grown with no P-fertilizer produced tuber starch with phosphorylation levels reduced to approximately 30% of the level found in plants grown with an ample supply of P. Thus, the level of starch phosphorylation can be modified by limiting the P-supply through the root system. Application of foliar P-fertilizer to the greenhouse-grown plants had no significant effect on the phosphorylation of the tuber starch.     

Potato tuber sugars, starch and organic acids in relation to ozone exposure

Summary Data from two Swedish and one Finnish open-top chamber experiments were combined to investigate effects of ozone exposure on potato (Solanum tuberosum L.) tuber content of starch, sucrose, fructose, glucose, malic, citric and ascorbic acids. The glucose, fructose and malic acid concentrations showed strong negative correlations with ozone exposure, while citric acid, consistently increased with ozone exposure. No ozone effects could be demonstrated on starch, sucrose or ascorbic acid concentrations. It is discussed to what extent the changes found in potato tuber composition can be explained in terms of ozone effects on tuber maturity. Ozone exposure was expressed as the accumulated exposure over a cut-off concentration of 40 nmol mol⁻¹ (AOT40) and as the accumulated uptake of ozone over an ozone uptake rate threshold of 7 nmol m⁻² s⁻¹ (CUO 7). The difference in ability of the exposure indices to explain observed effects was small.     

Total Phenolics Level,Antioxidant Activities and Cytotoxicity of Young Sprouts of Some Traditional Korean Salad Plants

The aim of this investigation was to study the antioxidant and anticancer activities of young sprouts of some traditional Korean salad plants. Total phenolics, antioxidant and anticancer activities of the methanol extracts from young sprouts of 11 salad plants were determined. The highest amount of phenolics was found in methanol extracts of Euonymus alatus (235.7 mg kg⁻¹), followed by Hypericum ascyron (197.1 mg kg⁻¹), Zanthoxylum piperitum (194.1 mg kg⁻¹) and Zanthoxylum schinifolium (142.5 mg kg⁻¹). Methanol extracts of E. alatus, H. ascyron, and Z. piperitum at 63 mg kg⁻¹ exhibited the highest dose-depend DPPH radical scavenging activity by 91.2, 91.2 and 83.9%, respectively. According to the MTT results, the methanol extracts from Stellaria aquatica, Eleutherococcus sessilifolrus and Z. schinifolium showed the highest anticancer activities against Calu-6 (IC50 < 25.0 μgml⁻¹) and from S. aquatica—the highest anticancer activities against SNU-601 (153.3 μgml⁻¹), following by E. sessilifolrus (196.7 μg ml⁻¹) and Amaranthus mangostanus (303.1 μgml⁻¹). Total phenolics were highly correlated with the DPPH, suggesting that they contribute to the antioxidant properties of the studied plants. In conclusion: young sprouts of Korean salad possess antioxidant and anticancer properties and could be used as a supplement to proper drugs.     

Impact of Stolbur Phytoplasmas on Potato Tuber Texture and Sugar Content of Selected Potato Cultivars

Potato stolbur is a phytoplasmal disease that seriously affects yield and tuber quality in South Eastern Europe, Russia and the Mediterranean areas. In 2007 and 2008, field experiments were carried out to determine stolbur resistance of processing potato cultivars at Sannicolau Mare (Romania) by determining consistency and concentration of reducing sugars (fructose and glucose), sucrose and phytoplasmas in potato tubers. In both years, non-symptomatic potato tubers showed sucrose levels in the range of 3,000 mg kg⁻¹ fresh weight (FW). In contrast, sucrose concentrations were up to 11,820 mg kg⁻¹ FW in 2007 and 19,560 mg kg⁻¹ FW in 2008 in tubers showing severe symptoms. These high values severely affect suitability of tubers for processing as sucrose serves as substrate for the formation of reducing sugars that are the limiting factor in fried potato production for Maillard-related discolouration. The cultivars examined differed considerably in susceptibility to stolbur disease. Whereas cvs. ‘Courage’ and ‘Lady Rosetta’ showed high numbers of diseased tubers and high sucrose concentrations, ‘Lady Claire’ had a lower incidence of symptomatic tubers and lower sucrose concentrations. However, fully resistant cultivars were not observed. Across all cultivars examined, phytoplasmal concentration was significantly higher in symptomatic tubers than in non-symptomatic ones.     

The potential for production of high quality seed potatoes in Tierra del Fuego Island, Argentina

Summary In Argentina, different areas are suitable for seed potato production: however, each has particular problems, mainly related to different pest and diseases. Tierra del Fuego Island is well isolated from traditional potato growing areas. Therefore, it was tested for its potential for seed production. The cultivars Achatt. Mailén INTA. Pampeana INTA and Spunta were grown in Río Grande, San Pablo and Ushuaia from 1991–1994. Nematode presence and aphid population dynamics were recorded. Average tuber yield ranged from 20.1–37.6 t ha⁻¹. After three years PVY and PLRV remained low (0–1% for different cultivars and locations). Moreover, seed tubers obtained were physiologically young. Long days, early frosts and strong winds may limit tuber yield in some years. The island can be considered as an ecological “safe haven” and is very suitable to obtain healthy and physiologically adequate seed potatoes.     

Potato and Human Exploration of Space: Some Observations from NASA-Sponsored Controlled Environment Studies

Future space exploration by humans will require reliable supplies of food, oxygen and clean water to sustain the expeditions. Potato is one of several crops being studied for such a “life support” role. Tests sponsored by the US National Aeronautics and Space Administration (NASA) confirmed the well-known short day tendencies for tuberisation, but also revealed that some cvs. (e.g., Norland, Denali and Russet Burbank) could tuberise well under continuous high light. Horticultural tests showed that plants grew well and tuberised readily using a nutrient film technique (NFT). CO₂ enrichment studies with potato showed typical C₃ responses in photosynthesis and yield, with maximum rates occurring near 1000 μmol mol⁻¹. The highest tuber yields from these controlled environment studies reached 19.7 kg FM m⁻² or equivalent to nearly 200 t ha⁻¹. This equated to a productivity of 38 g m⁻² DM m⁻² day⁻¹. Stand evapotranspiration (ET) rates ranged from 3.4 to 5.2 l m⁻² day⁻¹ throughout growth, while maximum ET rates for canopies could approach 10 l m⁻² day⁻¹. Harvest indices (tuber DM/total DM) typically ranged from 0.7 to 0.8, indicating that waste (inedible) biomass from potato would be less than that from many other crops. An experiment was conducted in 1995 on NASA’s Space Shuttle using excised potato leaves to study tuber formation at axillary buds during spaceflight. The results showed that tubers formed equally well in space as in the ground controls, indicating that reduced gravity should not be an impediment to tuberisation.     

Dimethylnaphthalene and diisopropylnaphthalene for potato sprout control in storage: 1. Application methodology and efficacy

Dimethylnaphthalene (DMN) and diisopropylnaphthalene (DIPN) isomers applied as sprout suppressants to stored potatoes (cv. Russet Burbank) were evaluated for effects on sprout length and weight compared to chlorpropham (CIPC). One application of CIPC at 22 mg a.i. kg^-1 of tuber fresh weight (f.w.), and one or two applications of DMN and DIPN at 100, 200, and 300 mg a.i. kg^-1 f.w. were applied as thermal aerosol fogs. Two applications of DIPN at 300 mg a.i. kg^-1 f.w. were as effective as CIPC in suppressing sprout growth during ten months of storage. DMN also suppressed tuber sprout growth but was not as effective as two applications of DIPN or one application of CIPC. One application of DIPN or DMN at 300 mg a.i. kg^-1 f.w. was an effective suppressant of sprout growth on a short-term basis. Whole tuber residue analyses were also conducted. After ten months in storage, DMN and DIPN residue concentrations were equal to or less than those of CIPC.     

Performance of Dimethomorph + Mancozeb Applied to Seed Potatoes in Early Management of Late Blight (<Emphasis Type="Italic">Phytophthora infestans</Emphasis>)

Treating seed potatoes with contact fungicides prevents infection of Phytophthora infestans from tuber to tuber during handling but does not prevent field infections in the young plant. Dimethomorph (DMM) 9% + mancozeb 60% (Acrobat MZ, BASF) can cover both aspects due to the contact and systemic action of mancozeb and DMM, respectively. Experiments were performed under greenhouse and field conditions (three seasons and two locations) with cvs Kennebec, Shepody, Spunta, Russet Burbank, and Ranger Russet. Immediately after cutting, seed pieces were treated with Acrobat MZ at doses equivalent to 2, 3, and 4 kg ha⁻¹. At any dose, Acrobat MZ protected healthy seed tubers against P. infestans infections. Acrobat MZ (4 kg ha⁻¹) also protected the foliage of all cultivars against artificial inoculation of P. infestans, assessed by the detached-leaf method. These effects were observed up to 30 days after emergence in greenhouse experiments and up to 28 days after crop emergence under field conditions in two growing seasons. In cv Spunta, significant foliage protection was observed up to 35 days after field emergence whereas in seed tubers of cv Kennebec planted in sandy soils, significant foliage protection persisted longer. Additional evidence for acropetal translocation of Acrobat MZ in field crops was also found. With this strategy, there is no need to apply contact or systemic fungicides early in the season, and spraying costs and environmental risks are also reduced.