Differential response of cold stored potato tubers to ethylene

The chip color of two potato varieties (Monona and Kennebec) processed directly out of 40 F storage changed in different directions after short exposure to ethylene and continued cold storage. Monona tubers produced much darker chips after ethylene treatment whereas non-enzymatic browning of Kennebec chips was considerably less after gassing. The distribution of pigmentation in chips prepared from both tubers was more uniform after ethylene treatment.     

Chip color of the developing potato tuber

Chip color was unacceptable from tubers of Kennebec in an immature condition soon after the tubers were set. Dark colored chips were also obtained from tubers harvested late in the season when soil temperatures were 50 F or less. Two high quality experimental varieties, F5889 in particular, gave excellent chip color regardless of tuber maturity all season and until soil temperatures in fall declined to 40 F. The data indicate that acceptable chip color may be obtained at most stages of tuber development in varieties of high chipping quality. Therefore when selecting seedlings from hybrid plant populations, chip color determined from selections made soon after tuber initiation could be useful. In a supplementary study no marked variations in chip color were obtained from tubers located different distances from the mother plant.     

Some storage characteristics of potato cultivar Atlantic

The cultivars Atlantic, Kennebec and Katahdin were compared as to their storability and cooking qualities for the storage seasons 1974–75 and 1975–76. The studies show Atlantic was equal to Katahdin and Kennebec with regard to storability, except that at storage temperatures above 40°F (4.5°C) for 6 months, sprouting was excessive. Storage losses due to Fusarium tuber rots from natural infection were higher in Atlantic than either Katahdin or Kennebec. The processing quality for chips and French fries of Atlantic was equal or slightly better when compared to the other varieties tested.     

A possible genetic source for chipping potatoes from 40 F storage

An interspecific hybrid ofS. phureja x USW1, a haploid of Katahdin, produced acceptable potato chips when processed directly from 40 F (4.5 C) storage during 3 years of testing. It was crossed with 11 interspecific hybrids. Tubers from these progenies were stored for 5 weeks at 40 F and then chipped immediately for 55 seconds in vegetable oil maintained at 375 F (190 C). Of 645 seedlings tested, chip color was acceptable in 17 and variable in 18. A group of 600 seedlings fromS. tuberosum parents treated comparably produced black-colored chips without exception.     

Chemical composition variations of tissues and processing characteristics in ten potato cultivars grown in Jordan

Ten certified potato cultivears (Ajax, Crystal, Kennebec, Labelle, Liseta, Mondial, Norchip, Signa Gold, Spunta and Vital) were grown at Jordan University Experimental Station in 1993. At harvest, tuber subsamples of each plot were analyzed for physical properties and chemical composition. Processed chips and fries were evaluated for appearance, color, aroma, texture, taste and overall acceptability. There was significant variation in tuber weight which ranged from 108.8 (Kennebec) to 148.7 g (Labelle), specific gravity which varied from 1.022 (Mondial) to 1.191 g/ml (Spunta), total solids which ranged from 18.9 (Ajax) to 23.9% (Vial), and chemical composition. Cultivars Liseta, Signa Gold, Mondial, Kennebec and Crystal produced highly acceptable chips and fries, while Ajax, Kennebec, Norchip and Spunta produced excellent fries only. All other cultivars produced less acceptable chips and fries.     

Potato chip color ratings of advanced selections from the Maine potato breeding program

Seven named varieties and three numbered selections from the University of Maine potato breeding program were compared for chip color at various conditions and lengths of storage. Although all selections tested were equal to or better than Kennebec in chip color, only Allagash Russet equaled Monona. Storage at 45° F (7.2° C) produced acceptable chip color at all time periods tested. After long term storage at 45° F, reconditioning at 55° F(12.8° C) was ineffective in improving chip color. Following storage at 38° F (3.3° C) acceptable chip color could be produced only by reconditioning at 70° F (21.1° C) for at least two weeks.     

Snowchip: A high yielding potato variety for Alaskan growers and processors

Breeding ad selecting potatoes in Alaska to develop a variety that could be depended upon to process into light-colored chips has resulted in the naming and release of Snowchip. It is a selection from the cross Stately × Ontario. The oval, uniform, light buff, shallow-eyed tubers are suitable for either fresh market or chipping. Dry matter content of Snowchip, over a three-year period, expressed as specific gravity significantly exceeded Kennebec, Alaska 114 and Green Mountain. The rest period of this cultivar is short as is its paternal parent Ontario. However, Snowchip keeps well in storage at 38°F or cooler. Light-colored chips have been made conventionally from the 1971, 1972 and 1973 potato crops.     

The effect of maleic hydrazide (potassium salt) on potato yield,sugar content and chip color of Kennebec and Norchip cultivars

A new formulation of maleic hydrazide (MH), a potassium salt formulation, was field tested for 3 years in Ontario to evaluate effects on yield performance, and on the sprouting and processing quality of cvs. Norchip and Kennebec potatoes. Foliar applied MH had no apparent effect on yield of potatoes, was effective in suppressing sprout growth, and had no effect on the sugar content (i.e., fructose, glucose and sucrose) of potatoes newly harvested and after 6 months storage. Although chip color varied from yearto-year, no consistent difference was found between the color of chips made from potatoes from untreated and MH-treated plants.     

Reducing sugar accumulation in progeny families of cold chipping potato clones

Two North Dakota breeding clones, ND860-2 and ND2221-6 accumulate very little reducing sugar in low temperature storage and will produce acceptably colored chips with little reconditioning. Progeny from diallel crosses of ND860-2, ND2221-6, Norchip and Kennebec were evaluated for reducing sugar and total sugar accumulation after 100 days of cold storage (3–4°C). Crosses of the North Dakota clones with Norchip or Kennebec produced families whose distributions were skewed towards the high parent with respect to reducing sugar values; about 2% had levels near the two low parents. Crosses between ND860-2 and ND2221-6 produced reciprocal families in which an average of 8% of the progeny had levels as low as these two parents.     

The effects of handling on chip color and sugar content of potato tubers

Color of chips made from potatoes (Solanum tuberosum L.) subjected to handling treatments was darker than of non-handled tubers in nine of ten experiments. ‘Monona’ and ‘Rosa’ appeared to be more vulnerable to the adverse effects of handling than were ‘Kennebec’ and ‘Norchip,’ but all cultivars were affected. Levels of fructose and glucose were elevated by handling. Sucrose also increased in all cultivars except ‘Kennebec.’ The handling effect was most noticeable early (December) or late (March or April) in the storage season. The effect of chilling did not appear to be intensified by handling.     

Evaluation of antioxidant activity of methanolic extract from peanut hulls in fried potato chips

Antioxidant activity of methanolic extract from peanut hulls (MEPH) was evaluated in fried potato chips during storage at 25 ^°C and 45 ^°C. Free fatty acids (FFA) and peroxide values (POV) were used as criteria to assess MEPH as an antioxidant. After six months storage at 45 ^°C potato chips treated with 1200 and 1600 ppm of MEPH showed lower values of FFA (0.083, 0.080%) and POV (30.0, 29.0 mEq/kg) than the control samples (FFA 0.377%, and POV 180 mEq/kg). Potato chips treated with BHA and BHT showed POVs of 29.0 and 25.0 mEq/kg whereas FFA values were 0.0086 and 0.074%, respectively, after six months storage at 45 ^°C. These results illustrate that MEPH, at various concentrations, exhibited very strong antioxidant activity which was almost equal to synthetic antioxidants (BHA & BHT). Subjective evaluation studies also showed that potato chips treated with 1200–1600 ppm MEPH after six months storage at 45 ^°C, were organoleptically acceptable.     

Sensory quality of Ontario potatoes compared with principal varieties grown in Maine

Baked potatoes of five varieties grown at the same location in Maine were evaluated for quality shortly after harvest and after six months’ storage by sensory panels of 16 and 18 members. The Ontario variety was rated significantly poorer (P = 0.05) in flavor than Russet Burbank, Katahdin, and Superior, but did not differ from Kennebec when tested in November. Following storage, however, these differences were not significant. At the 1% level of detection, Ontario tubers were judged significantly less mealy than those of the Russet Burbank, Katahdin, Superior, and Kennebec varieties (Nov. Kennebec excepted) and were grayer (Mar. Superior excepted). Due to the low mealiness ratings and grayness of flesh, tubers of the Ontario variety were considered less desirable for table stock than potatoes of other principal varieties grown in Maine.     

Effect of variety and harvest date on tuber sugars and chip color

The major tuber sugars—glucose, fructose and sucrose — in tubers of the Red Pontiac, Kennebec and Monona potato varieties harvested five times during the 1970 growing season were determined quantitatively by a gas-liquid Chromatographic technique. Also, chips were made from tubers and chip color was measured objectively and reported as Rd values. Red Pontiac tubers produced the darkest-colored chips (Rd-15.5), and its tubers tended to accumulate the highest levels of the three sugars. The major difference between Monona, which produced chips with the lightest color (Rd-21.1), and Kennebec (Rd-19.5) was the very low level of glucose found in the tubers of Monona. Varieties produced chips lightest in color at the second (8/31) or third (9/15) harvest dates. Conversely, darkest-colored chips were obtained from each variety at the fourth harvest date (9/28). This was attributed to the cool, wet weather. Sugar content also varied during the harvesting schedule. Glucose content changed little until late in the season when an increase occurred. Fructose tended to decline until the final harvest when a distinct increase was obtained. Sucrose declined significantly through the third harvest, but changed little thereafter.     

Cultivar response to Fusarium storage rot as affected by two methods of seed origin propagation; Clonal selection andin vitro culture

Progeny tubers from seed potatoes originating from either a traditional clonal selection method or the more modernin vitro tissue culture method of propagation were tested for storage rot response following inoculation of three tuber sites with twoFusarium species. Significant differences were found among disease responses for the twoFusarium species and for the four cultivars tested. Disease symptoms were less severe forF. solani var.coeruleum than forF. sambucinum. Fusarium sambucinum caused less disease in Superior than Kennebec, Russet Burbank and Sebago. Seed propagation method did not significantly affect disease response except for one case;in vitro culture of Kennebec had less disease due toF. sambucinum at the tuber side inoculation site than clonal selection. Kennebec and Superior inoculatedF. sambucinum had significant differences with respect to the number of years of field propagation for the tuber side inoculation site and for the tuber mean rot index. Significant differences in number of years of field propagation were also found for eye-ends of Superior tubers and stem ends of Russet Burbank tubers inoculated withF. solani var.coeruleum.     

Potato seed-piece treatment in Ontario

Warming Segabo and Kennebec seed potatoes for 14 days at 70 F in daylight caused the resultant plants to emerge sooner than those from seed kept at 40 F until planting, especially if soil temperatures remained around 50 F. However, neither this practice nor treating seed pieces with insecticidal and fungicidal dusts gave any increases in yield when compared with untreated seed if the seed was planted immediately after cutting. A yield reduction may occur if seed treated with diazinone is planted in soil which remains cold for several weeks.     

Processing characteristics of Solanum tuberosum—S. stoloniferum hybrids

Two hybrids having high total solids were compared with established commercial varieties for processing into french fries, potato chips, and potato flakes. Russet Burbank was used as a control for potato flakes and french fries, and Kennebec for potato chips. The hybrids were processed initially at harvest and at two intervals after harvest. The solids in the hybrids varied from 23.0% to 26.9% and the products generally had a better color and yielded more product per pound of raw material than the controls. The hybrids had a high level of xanthophyl, stable in the french fries and potato chips but unstable in the potato flakes. Antioxidants retarded the loss of the yellow color in the flakes. Oil absorption was found to be inversely related to solids in the potato chips and french fries. By means of sensory evaluation, the hybrids were generally considered different from the controls with respect to color, flavor, and texture but no preferences were obtained. Potatoes with high solids result in more finished product per pound of raw material.     

低温干燥贮藏包衣和非包衣玉米种子活力及生理差异性研究

以玉米品种NK618和济单7号的包衣和非包衣种子为试验材料,低温干燥贮藏16个月、28个月和40个月,分别测定种子的发芽、活力指标,测定幼苗的SOD、POD、CAT、MDA、脯氨酸等含量,探讨低温干燥贮藏条件下玉米种子的可种用时间,比较包衣和非包衣玉米种子间的贮藏差异性及生理变化。结果表明,低温干燥条件下玉米种子贮藏16个月,包衣种子的各项发芽及活力指标比新种子显著降低,非包衣则无显著性变化;贮藏28个月,NK618和济单7号非包衣种子的发芽率分别是91%和87%,均可作种用,包衣种子已无种用价值;贮藏40个月时包衣和非包衣种子均不可作种用。包衣种子比非包衣种子更易老化,幼苗的SOD、POD、CAT含量均随贮藏时间延长而降低,贮藏28个月两个品种包衣和非包衣3种酶含量均比对照新种子含量降低,但差异显著性不同;MDA和脯氨酸含量随贮藏时间延长而增加,贮藏40个月时两个品种的包衣和非包衣种子萌发幼苗MDA含量均达最大值。     

Chipping performance of three processing potato cultivars during long-term storage at two temperature regimes

Three potato cultivars (Russet Burbank, Norchip, and Gemchip) grown with nitrogen applied at three rates were stored at two temperature regimes (Treatment 1: 13 months at 10 CTreatment 2: 1 month at 10 C; followed by a 1 C decrease per week until tubers were 4 C; followed by 6 months at 4 C; followed by a 1 C increase per week until tubers were 10 C; followed by 3 months at 10 C). Tuber chemical components and potato chip appearance were measured at harvest and after 3, 6, 9, 11, 12, and 13 months; these measurements were performed within 24 hours of the time potatoes were removed from storage. Sugar responses (tuber glucose, fructose, sucrose) and potato chip appearance were affected by cultivar over time in both years and storage temperatures. Russet Burbank tubers displayed a significantly higher glucose forming potential and produced darker appearing chips, regardless of storage temperature or time in storage, compared to Norchip and Gemchip. Potatoes receiving a cold-storage treatment contained less sugar and produced lighter appearing chips after 12 months storage compared to tubers stored at a constant 10 C for 12 months. The linear association between tuber chemical components and potato chip appearance varied with storage temperature.     

Yield and relationships among tuber size,sucrose and chip color in six potato cultivars on various harvest dates

Cultivars were harvested biweekly for yield, weekly for sucrose determinations, and stored for chipping. At the last harvest Crystal was highest in total and marketable yield. Specific gravity was higher in Lemhi, Russet Burbank, and Norchip than in Kennebec, Crystal and Dakchip. Storage tests showed Norchip had superior chipping color to other cultivars. Dakchip had better color after short rather than after long-term storage, while the opposite was true for Kennebec and Russet Burbank. Lemhi and Crystal were marginal in color throughout storage. Sucrose (mg sucrose/g fresh tuber) expressed as a sucrose rating (SR) ranged from 1.2 to 11.9 among the various cultivars and harvest dates. Correlation between SR’s and tuber size within cultivars ranged from ?.91 to ?.97. Variability in sucrose content of immature tubers explained 70% of the variability in chip color among cultivars after storage from four to six months. Sucrose levels may be used to predict relative chipping quality of various cultivars after moderate to long-term storage if measured during early tuber development when differences in sucrose concentration are greatest among cultivars.     

Some factors influencing the pH of apical and basal portions of Russet Burbank and Norgold Russet potatoes

Studies were made of pH changes of apical and basal portions of Russet Burbank and Norgold Russet potatoes during growth and in storage. Russet Burbank had a higher pH of the apical portion during the later stages of growth as compared to the basal portion. No significant differences between the two portions were found during growth with Norgold Russet. After a period of moisture stress the pH of the basal portion of Russet Burbank dropped significantly. The basal portion of both varieties at higher specific gravities had higher pH after storage than the apical portion. A highly significant negative correlation was obtained after storage between reducing sugar levels of tubers of different specific gravities and pH levels in both varieties. There were no significant differences in pH among storage temperatures of 34, 38, 42 and 45 F. However, the pH level at 48 F storage was significantly higher than at the other temperatures. The pH level of tubers from seedlings and varieties were poorly correlated with their reducing sugar contents after storage. It appears that pH can be an indicator of potential chip color only within the confined limits of a specific lot.