Antibrowning effect of commercial and acid-heat coagulated whey on potatoes during refrigerated storage.

Potato color turns to brown after some process such as peeling, cutting, and slicing. In this research, the effect of acid-heat coagulated whey and commercial whey solutions on the color, polyphenol oxidase, phenylalanine ammonia-lyase activity, malondialdehyde, hydrogen peroxide content of potatoes were compared with pure water (control) immersion and sodium hydrogen sulfide solution. According to color results, there was no significant (P > 0.05) difference was found in the L* and b* values, browning index, and whitening index of the treatment groups. The polyphenol oxidase activity of the sulfide and commercial whey solution groups decreased from the initial values on day 3 then increased over that value. The use of the whey solution in preventing polyphenol oxidase activity showed a similar curve with the use of the sulfide solution. A rapid increase was observed in the malondialdehyde and hydrogen peroxide values of all treatment groups during the first 3-day storage. PRACTICAL APPLICATION: Immersion of potato cubes to whey protein solution prevents the browning and inhibits polyphenol oxidase activity. The browning index of the samples was not affected by the immersing water or whey solutions.

Potato (Solanum tuberosum L.) can be grown safety on human consumption in slight Hg-contaminated soils across China mainland.

Mercury (Hg) exposure poses serious health risks to humans, resulting in extensive investigations examining Hg accumulation, biotransformation and uptake in crops. In this investigation, Hg accumulation in potato tubers due to bioaccumulation processes was determined and bioconcentration factors affecting bioaccumulation were identified using a greenhouse experiment. Our results showed that the percentage of available Hg concentrations from total Hg in soil samples were less than 1.2%, indicating that soils used in our experiment exhibited a high binding strength for Hg, with alkaline soil recording the lowest available Hg/total Hg ratio. Results indicated that soil type and Hg treatment, as well as their interactions, significantly affected Hg accumulation in potato tubers (P < 0.01). Importantly, our results also indicated that potatoes grown in soil with a Hg concentration two times higher than the Chinese Environmental Quality Standard exhibited no obvious toxic effects on humans; Bioconcentration factors (BCF) values (<0.04) suggested that potatoes can be considered as a low Hg accumulating species and suitable for human consumption. Potato yields in acidic soil were lower than those in neutral or alkaline soils, making this medium unsuitable for growth.

Colorado Seed Potato Certification Data Analysis Shows Mosaic and Blackleg are Major Diseases of Seed Potato and Identifies Tolerant Potato Varieties.

Seed potato certification programs aim to limit disease incidence in planting material to levels below a threshold that causes significant losses to seed potato buyers. Records maintained for seed potato certification can be analyzed for trends in seed potato varietal mixture and disease incidences over time. We used logistic regression models to determine effects of year, potato variety, and their interaction on the incidences of potato diseases and disorders based on seed potato certification data collected in Colorado from 2012 to 2016. The effect of seed generation of important varieties on the incidence of common potato diseases was also quantified. Among the documented diseases, mosaic, caused primarily by Potato virus Y, is a persistent problem leading to high percentage of seed lot rejections in both summer and winter inspections, while blackleg, caused by Dickeya spp. and Pectobacterium spp., was a common disease causing summer rejections. The model demonstrated year, potato variety, and their interaction were key factors contributing to incidence of varietal mixture, or one or more potato diseases and disorders. For summer inspections, our models identified 53, 42, and six varieties sensitive to mosaic, blackleg, and leafroll, respectively. There were 17, 15, and six varieties that were tolerant to mosaic, blackleg, and leafroll regardless of pathogen pressures in the environment. For winter inspections, 51 varieties were sensitive to mosaic and three to leafroll, whereas 45 and one were relatively tolerant to mosaic and leafroll. The pattern of seed generation effects of selected potato varieties on mosaic and blackleg incidence was inconsistent across inspection years. In addition, we observed a significant negative correlation between the relative abundance of the green peach aphid, Myzus persicae, and mosaic in winter inspections. Mosaic incidences in summer and leafroll incidences were not influenced by common aphid species captured or total aphids in the valley. These results identify mosaic and blackleg as major causes of seed potato rejections and downgrades, sensitive and tolerant varieties, and provide suggestions for improving integrated crop management practices in Colorado.

The transcriptome of the reference potato genome Solanum tuberosum Group Phureja clone DM1-3 516R44.

Advances in molecular breeding in potato have been limited by its complex biological system, which includes vegetative propagation, autotetraploidy, and extreme heterozygosity. The availability of the potato genome and accompanying gene complement with corresponding gene structure, location, and functional annotation are powerful resources for understanding this complex plant and advancing molecular breeding efforts. Here, we report a reference for the potato transcriptome using 32 tissues and growth conditions from the doubled monoploid Solanum tuberosum Group Phureja clone DM1-3 516R44 for which a genome sequence is available. Analysis of greater than 550 million RNA-Seq reads permitted the detection and quantification of expression levels of over 22,000 genes. Hierarchical clustering and principal component analyses captured the biological variability that accounts for gene expression differences among tissues suggesting tissue-specific gene expression, and genes with tissue or condition restricted expression. Using gene co-expression network analysis, we identified 18 gene modules that represent tissue-specific transcriptional networks of major potato organs and developmental stages. This information provides a powerful resource for potato research as well as studies on other members of the Solanaceae family.

Efficacy of potato seeds disinfection products to control Erwinia spp.

Erwinia spp. provokes soft rot on potato tubers during storage. No disinfection products are available on the market in the European Union to control these bacteria. We tested 3 products presented as good candidates to cure potato tubers from bacterial diseases. First, Anthium 500 (Du Pont de Nemours) a product based on chlorine dioxyde, then Phostrol (Nufarm) with phosphoric acid as a.i. and finally Solucuivre (Proval), a copper based product. We firstly managed disinfection trials: high Erwinia contaminated potato seed samples were treated by immersion and were then incubated, we observed the percentage of tubers rotting. Secondly, we managed protection trials: protected healthy tubers were incubated during 23 days in contact with rotting tubers. We evaluated weight loss after symptoms development. No tested product was effective to control Erwinia spp. on seed tubers in our trials conditions. Furthermore, we observed more rot development after Phostrol and Solucuivre application. We suppose that the product couldn't reach the latent bacteria and weakened the tubers. No protection effect was observed.

Factors dominating adhesion of NaCl onto potato chips.

In this study, the adhesion factors examined were time between frying and coating, surface oil content, chip temperature, oil composition, NaCl size, NaCl shape, and electrostatic coating. Three different surface oil content potato chips, high, low, and no, were produced. Oils used were soybean, olive, corn, peanut, and coconut. After frying, chips were coated immediately, after 1 d, and after 1 mo. NaCl crystals of 5 different particle sizes (24.7, 123, 259, 291, and 388 microm) were coated both electrostatically and nonelectrostatically. Adhesion of cubic, dendritic, and flake crystals was examined. Chips were coated at different temperatures. Chips with high surface oil had the highest adhesion of salt, making surface oil content the most important factor. Decreasing chip temperature decreased surface oil and adhesion. Increasing time between frying and coating reduced adhesion for low surface oil chips, but did not affect high and no surface oil chips. Changing oil composition did not affect adhesion. Increasing salt size decreased adhesion. Salt size had a greater effect on chips with lower surface oil content. When there were significant differences, cubic crystals gave the best adhesion followed by flake crystals then dendritic crystals. For high and low surface oil chips, electrostatic coating did not change adhesion of small size crystals but decreased adhesion of large salts. For no surface oil content chips, electrostatic coating improved adhesion for small salt sizes but did not affect adhesion of large crystals.

Irradiation in combination with higher storage temperatures maintains chip-making quality of potato.

Freshly harvested and well-suberized potato (Solanum tuberosum) of varieties Kufri Jyoti, Lady Rosata, Kufri Laukar, and Hermises were processed by radiation at 78/149 Gy (D(min)/D(max)) dose and stored at 12 +/- 2 degrees C for 8 mo from March to October for assessment of chip-making quality. The firmness of the tubers in all the varieties processed remained unchanged during the period of storage. Chips of the desirable quality could be prepared from 7-mo stored Lady Rosata, Hermises, and Kufri Jyoti varieties, whereas, in Kufri Laukar, the quality chips could be prepared with tubers stored not beyond 5 mo. In the present study, varietal differences were found to influence the chip-making quality of irradiated potato. Tubers with high reducing and total sugar (>2%) were found to be unsuitable for chip-making. The quality of chips, however, was not affected much by the change in internal color of the tuber during storage beyond 6 mo. The results suggested the efficacy of gamma irradiation for ensuring availability of the processing quality potato during lean periods from September to October.

Physical properties of acetylated and enzyme-modified potato and sweet potato flours.

Textural profile, pasting behavior, gelatinization characteristics, sedimentation volume, and gel consistency of acetylated (Ac) and enzyme (glucoamylase)-modified (EM) potato and sweet potato flours have been investigated to determine their suitability in products such as baked goods, soup, and pudding. Dough hardness of Ac and EM samples was significantly higher than their native samples (P < 0.01). Dough cohesiveness of modified potato did not change, while it decreased in modified sweet potato. With increase in moisture, textural properties of modified samples, in general, showed reduced values. Rapid Visco Analyser showed least pasting viscosities of Ac flours due to restricted swelling of starch granules while EM flours exhibited high viscosities. Acetylated samples showed reduced gelatinization temperature (GT), and enthalpy (DeltaH) compared to native samples, whereas enzyme-treated samples showed no significant changes in GT, indicating their comparable crystallinity values with those of native samples. Modified flour samples had lower sediment volumes and gel consistency, and the gel consistency of EM flour correlated with its cold paste viscosity.

Quality of organically and conventionally grown potatoes: four-year study of micronutrients, metals, secondary metabolites, enzymic browning and organoleptic properties.

The quality of potatoes from organic and conventional farming was investigated in this study. Tubers of eight potato varieties, organically and conventionally produced at one or two geographical sites in controlled field trials, were collected in four consecutive harvests from 1996-1999. The parameters analysed included nitrate, trace elements (As, Cd, Co, Cu, Fe, Hg, Mn, Ni, Pb, Se, Zn), vitamin C, potato glycoalkaloids, as well as chlorogenic acid, polyphenol oxidase and rate of tuber enzymic browning. The results indicated lower nitrate content and higher vitamin C and chlorogenic acid content to be the parameters most consistently differentiating organically from conventionally produced potatoes. Elevated concentrations of glycoalkaloids were also observed throughout the experiments in some potato varieties grown in organic farming systems. Principal component analysis (PCA) of the analytical and other data using three PCs confirmed a good separation between the organically and conventionally produced potatoes when studied in single crop years. However, score-plots (objects) and loading-plots (variables) of pooled results from the consecutive harvests showed that between the years' changes and also variety as well as geographical variations are equally or more important factors determining the quality of potatoes than the farming system. Further studies of various marker compounds of potato quality related to the organic or conventional farming systems should be performed before unbiased information can be given to the consumers.

Antioxidative effects of alpha-tocopherol and ascorbyl palmitate on thermal oxidation of canola oil.

Canola oil, with and without added alpha-tocopherol and ascorbyl palmitate, was used to deep-fat frying potatoes once per day for 10 day or once per week for 10 weeks. Changes in chemical and physical properties were monitored. Refractive index, free fatty acids and absorbance at 232 and 270 nm increased with frying time. Smoke point, 'L' color index, iodine value and the C18:2/C16:0 ratio in the oil decreased with the frying time. According to smoke point, which shows the time of the oil should be discarded, canola oil without antioxidant (control) can be used safely 8 times daily or 7 times weekly. For canola oil with antioxidant (oil + alpha-tocopherol + ascorbyl palmitate), the smoke point did not decrease below 170 degrees C in both daily and weekly fryings. This showed that canola oil with antioxidant could be used safely at least 10 times for both frying intervals. In both daily and weekly fryings, the addition of 200 ppm alpha-tocopherol and 200 ppm ascorbyl palmitate increased the oxidative stability of canola oil.

Sustainable soil management practices and quality of potato grown on erodible lands.

Land productivity can decline when top soil is lost. In Kentucky, limited resource farmers often produce vegetable crops on erodible lands. The objectives of this study were 1) to quantify the impact of three soil management practices (SMPs) on quantity of potato produced on erodible land, 2) to evaluate the impact of pyrethrin and azadirachtin insecticides on potato tuber quality, and 3) to assess the impact of yard waste compost on the chemical composition (ascorbic acid, free sugars, phenol contents) of potato tubers. Potatoes (Solanum tuberosum L. cv. Kennebec) were grown in a silty loam soil of 10% slope. Plots (n= 18) were 3.7 m wide and 22 m long (10% slope), with metal borders of 20 cm above ground level. Two botanical insecticides, Multi-Purpose Insecticide (containing pyrethrin 0.2%) and Neemix 4EC (containing 0.25% azadirachtin) were sprayed twice on potato foliage during each of two growing seasons (1997 and 1999) at the recommended rates of 6 lbs and 2 gallons.acre(-1), respectively. The SMPs were tall fescue strips (FS) intercropped between each two potato rows, soil mixed with yard waste compost (COM) and no-mulch (NM) treatment (roto-tilled bare soil). The experimental designwas a 2 x 3 x 3 factorial with main factors of two insecticides and three SMPs replicated three times. Average potato yield was lowest in NM and FS and highest in COM treatments. Yield obtained from the bottom of the plots was greater than that obtained from the top of plots. Tuber defects (rot, scab, sun green, hollow heart, necrosis, and vascular discoloration) were significantly different between the two growing seasons. The two insecticidal treatments did not have much influence on potato yield or tuber defects. Tubers obtained from tall fescue treatments had low levels of ascorbic acid and reducing sugars compared to compost treatments.

Residue levels of chlorpropham in individual tubers and composite samples of postharvest-treated potatoes.

Chlorpropham, a herbicide and sprout suppressant, is used on stored potatoes to prolong the storage period without deterioration of produce quality. Data for residue concentrations on an individual tuber basis are required by WHO for the estimation of the variability factor. In this study, the levels of chlorpropham in individual tubers and in composite samples were determined. The distribution of chlorpropham between the peel and the tuber flesh was examined, and the fate during the cooking process (washing, boiling, frying) was studied. The concentrations in individual tubers ranged from 1.8 to 7.6 mg/kg 10 days postapplication (mean 3.8 mg/kg, RSD 39%), from 0.7 to 4.0 mg/kg 28 days postapplication (mean 2.9 mg/kg, RSD 28%), and from 0.8 to 3.8 mg/kg 65 days postapplication (mean 2.2 mg/kg, RSD 48%). The calculated residues in composite samples 10 days postapplication ranged from 4.3 to 6.1 mg/kg (mean 4.9 mg/kg, RSD 20%). Those in samples taken 28 days postapplication ranged from 3.1 to 4.2 mg/kg (mean 3.8 mg/kg, RSD 15%). The concentrations determined in composite samples of whole tubers 65 days postapplication ranged between 2.6 and 3.2 (mean 2.9 mg/kg, RSD 11%). Peeling removed 91-98% of the total residue; washing reduced residues by 33-47%. Detectable residues were found in boiled potatoes and the boiling water, and in french fries and the frying oil. Monitoring data on commercial prefried frozen french fries are reported.

[Nitrate and nitrite content in potatoes from ecological and conventional farms]. / Azotany i azotyny w ziemniakach z gospodarstw ekologicznych i konwencjonalnych.

The aim of this investigation was to determine nitrate and nitrite content in potatoes from ecological and conventional farms. The influence of variety on nitrate and nitrite content was also evaluated. Vegetables and potatoes from ecological cultures are supposed to contain less nitrates and nitrites and on this basis could have been advised for children, sick and people in special physiological stages. Nitrite content was determined colorimetrically, with sulfanilic acid, nitrate content was determined following reduction of nitrites by means of metallic cadmium. The results showed significantly lower nitrate content in potatoes from ecological farms, and almost twice higher in those from conventional farms. The nitrite content showed no differentiation in conventional and ecological farms. Within three varieties of potatoes (sokól, bryza, ania) significantly highest content of nitrate was determined in bryza. Considering low nitrate level potatoes from ecological farms could be advised for children and sick people, but for the complete safety evaluation also content of other contaminants (i.e. heavy metals) have to be assessed.

[Mathematical modeling of the effects of chemical pollutants on the quality of agricultural crops]. / Matematicheskoe modelirovanie vliianiia khimicheskikh zagriaznitelei na kachestvo sel'skokhoziaistvennykh kul'tur.

Detergents, lead, and nitrogen fertilizers were tested for their effects on the level of sugar in the beets and that of starch in the potatoes. Models were developed for estimating the quality of potatoes and beets grown under irrigation and soil nitrogen fertilization. Lead made the greatest contribution to the lowering sugar in the beets and starch in the potatoes.

High-performance liquid chromatographic determination of the glycoalkaloids alpha-solanine and alpha-chaconine in 12 commercial varieties of Mexican potato.

The glycoalkaloid content in 12 commercial varieties of Mexican potatoes was measured by HPLC in both the peel and the flesh of the potato. The principal glycoalkaloids alpha-solanine and alpha-chaconine were present in higher concentration in the peel than in the flesh of all varieties. The main alkaloid in the peel of the potatoes was alpha-chaconine and comprised about 65-71% of the total glycoalkaloids. The high concentration of alpha-chaconine in peel, which is more toxic than alpha-solanine, gives more protection to the tuber against predators. The total alkaloids in the peel of Alpha, Juanita, Michoacan, Norteña, Rosita, and Tollocan varieties were higher than the limit recommended for food safety. However, the peel represents less than 10% of the total tuber in most of the varieties. The total alkaloids contained in the peel of Atzimba, Lopez, Marciana, Montsama, Murca, and Puebla was lower than the limits recommended for food safety. The glycoalkaloid content in the boiled peeled potatoes was less than 9 mg/100 g but in Alpha, Montsama, and Puebla varieties, both glycoalkaloids were absent. According to the results, the consumption of the 12 commercial varieties of Mexican potatoes does not represent any danger to human health.

[A comparison of selected parameters of potatoes health quality from ecologically oriented and conventional farms]. / Porównanie wybranych parametrów jakosci zdrowotnej ziemniaków z gospodarstw ekologicznych i konwencjonalnych.

The aim of work was to compare nutritional quality and wholesomeness of the potatoes from ecological (ECO) and conventional (CONV) farms. Other aim was to check if the west-european data telling about better nutritional quality of ECO potatoes can be confirmed in Polish agricultural conditions. Nine ECO farms located in Torun and Sieradz provinces, having EKOLAND's certification were selected to study. A neighbour CONV farm with similar production conditions was selected to each ECO farm. ECO farmers manured potatoes with composted cow manure or compost giving on average 30 t/ha. CONV farmers used mineral fertilizers NPK in 1:1:1,5 ratio giving 100 kg N/ha. In the autumn several compounds were determined in potatoes: the contents of dry matter according to PN-88/R-04013, the contents of nitrates and nitrites according to Draft International Standard ISO, the contents of Pb and Cd by means of ASA method and the contents of vitamin C as L-ascorbic acid according to PN-90/A-75101/11. The ECO potatoes contained in both years significantly less nitrates than CONV potatoes. In 1992 the nitrates contents was much higher in both kinds of potatoes than in 1993. The nitrites contents was in both years higher in CONV potatoes but the difference was statistically significant only in 1993. The lead contents was low in both kinds of potatoes and didn't exceed permissible level. The cadmium contents was in 1992 significantly higher in CONV tubers than in ECO tubers and exceeded permissible level. In 1991 and 1993 both kinds of tubers contained similar cadmium levels. The contents of dry matter and vitamin C was similar in both kinds of tubers. The study has shown that ECO potatoes were more wholesome than CONV potatoes. The results obtained in Polish agricultural conditions confirmed west-european data.

Source and amount of carbohydrate affect postprandial glucose and insulin in normal subjects.

To determine if source and amount of carbohydrate affected postprandial glucose and insulin responses, seven nondiabetic subjects consumed 0, 25, 50, 75 or 100 g carbohydrate (total carbohydrate minus total dietary fiber) portions of barley, spaghetti, bread or potato. By ANOVA, both source and amount of carbohydrate had significant effects on incremental response areas for capillary glucose (P = 0.001), plasma glucose (P = 0.01) and plasma insulin (P = 0.03), but there was no source x amount interaction. By regression analysis, source of carbohydrate explained a similar amount of the variability of glucose and insulin responses, 46-64%, as the amount of carbohydrate, 47-57%. Together, carbohydrate source and amount accounted for 85-94% of the variability of mean glucose and insulin responses. We conclude that, for individual foods with different glycemic indices, both source and amount of carbohydrate influence the postprandial glucose and insulin responses of nondiabetic subjects.

Tissue alpha-tocopherol retention in male rats is compromised by feeding diets containing oxidized frying oil.

To investigate the effect of dietary oxidized frying oil (OFO) on tissue retention of alpha-tocopherol (alpha-T). Long-Evans male weanling rats were divided to four groups based on a 2 x 2 factorial design. Two groups were fed 15% OFO diets, and the remaining two groups were fed control diets in which OFO was replaced by vitamin-E-stripped fresh soybean oil. Vitamin E as all-rac-alpha-tocopheryl acetate was added at the concentration of either 50 (normal E) or 500 (high E) mg/kg diet. The OFO sample was prepared by deepfrying sticks in fresh soybean oil at 205 +/- 5 degrees C for four 6-h periods. After 6 wks of feeding, alpha-T concentrations in most tissues were significantly lower in rats fed OFO diets (P < 0.05) than in the control groups. For rats fed the OFO diet with the normal vitamin E concentration, the alpha-T concentration is epididymal fat pad, plasma, liver, kidney, muscle, brain and lung were 29-64% those of the corresponding control group (P < 0.05). The interaction between the two dietary factors on tissue alpha-T was significant in liver, spleen, and adrenal gland. In these three tissues, the differences between the normal and high dietary vitamin E groups were less in rats fed the OFO diets than in rats fed the control diets. The tissue alpha-T concentrations of the high vitamin E OFO group were comparable with or higher (P < 0.05) than those of the normal vitamin E control group, indicating that the negative effect of OFO on tissue alpha-T concentration can be alleviated by dietary supplementation of vitamin E. Compared with the controls, rats OFO diets had significantly higher tissue thiobarbituric acid reactive substances (P < 0.05). Because the amount of alpha-T directly added into the test oil samples was not significantly decreased through an incubation (at 37 degrees C) period of up to 10 d, the inefficient absorption and/or enhanced catabolism or turnover of vitamin E may be involved in the inferior tissue alpha-T retention of OFO fed rats.