Sensory evaluation as a tool in breeding potatoes for French fries and flakes

Standardized sensory evaluation of advanced breeding clones developed in the research program of the Horticulture Department at North Dakota State University has been conducted annually since 1980. Procedures used by the USDA-ARS Potato Research Laboratory for processing tubers into partially fried french fries or flakes are described along with the procedures used for finish-frying of the fries and rehydrating the flakes in preparation for sensory evaluation in the Food and Nutrition Department at North Dakota State University. Following brief training, panelists evaluate the fries and flakes from each clone in triplicate for color, flavor, and texture. Procedures for determining length of fries and limpness of fry strips are described. Samples of 334 clones prepared as french fries and 135 clones prepared as flakes have been evaluated. Examples are given of types of data collected with interpretation of results in relationship to their use in the breeding program.     

Development of the Frozen French Fry Industry in South Africa

Potato processing is becoming particularly popular in developing countries and French fries are the main product being developed. This paper describes the South African frozen French fry industry, identifying aspects for improvements for further growth. Although South Africa produces over two million tonnes of potatoes per year, only 17 to 20% are processed, mainly as frozen French fries. While this is a larger production achievement than in the past, trends in consumption show that the frozen French fry industry has potential for further growth. Industry expansion is limited by the shortage of suitable raw potato stock linked to cultivar and potato production capacity constraints for frozen French fry processing. The country relies mainly on two processing cultivars produced in localized areas, for which yields are also threatened by unpredictably detrimental weather conditions. Produce shortages often lead to subsequent importation of products from other countries. The lack of cultivar-specific information on the amount of land used, production tonnages and yield achievements restricts diagnosis of specific factors contributing to this shortage. Based on the overall crop performance, a region-based approach is suggested to improve yield achievements of the few cultivars used for frozen French fry processing in the country. This could be achieved by optimizing natural resource management, particularly irrigation, fertilizer and land use, in the four agro-climatic regions contributing to the processing industry. Furthermore, the number of French fry processing cultivars can be increased by increasing financial investment on local breeding efforts to develop new cultivars and by focusing foreign cultivar adoption on processing needs to increase the genetic diversity and safeguard against the effects of climate change.     

Effect of storage period, cultivar and two growing locations on the processing quality of french fried potatoes

The source of raw potato tubers and the tubers’ duration of storage have a significant effect on color and texture of french fries. Controlling these variations is crucial to ensuring a consistent, high-quality end product. Russet Burbank and Shepody potatoes grown at two sites in Manitoba, Canada were stored for 9 and 11 months in 1994, and for 1 and 3 months in 1995, to determine the effects of short-term storage period, cultivar, and two tuber-growing locations on fry color and texture. French fry texture was measured by a puncture test, and peak force and peak deformation used as indices of textural quality. Large peak forces and deformations were assumed to be indicative of improved textural quality. Hunterlab L (lightness) value was used to determine fry color, higher values being associated with improved color quality. Fries processed from 11-month-old tubers had improved color and textural quality compared to those processed from 9-month-old tubers. Fries processed after 3 months tuber storage were darker in color but firmer in texture than fries processed from tubers after 1 month of storage. Differences in texture and color between the two cultivars were more evident with prolonged storage; fries processed from Russet Burbank potatoes were superior in texture and lighter in color than fries made from Shepody potatoes. With respect to site, fries processed from potatoes grown at Portage had better texture but darker color than those processed from Carberry potatoes. It was postulated that the calcium content of the soils may be responsible for both these results.     

Pectic substances and the texture of french fried potatoes

French fries made from low specific gravity potatoes are poor in texture and soggy in appearance. High specific gravity potatoes, on the other hand, produce mealy, firm and good-textured french fries. A comparison of raw potatoes of high and low specific gravity for protopectin, the degree of esterification, water-soluble pectins and divalent cations revealed no significant differences. Low specific gravity potatoes, however, were found to contain significantly higher levels of free calcium and lower degree of esterification of water-soluble pectins. Similar comparisons of french fries made from these potatoes showed that low specific gravity fries had a higher degree of protopectin de-esterification, greater breakdown of protopectin and higher levels of free calcium. It was concluded that protopectin of low specific gravity potatoes possesses fewer and/or weaker cross linkages, is poorly polymerized, and a substantial percentage of it breaks down on frying. This weakens the cell wall and results in a french fry of poor texture.     

Sensory quality of French fries prepared from BelRus and Russet Burbank potatoes

Frozen par-fries were processed in January, February, and March using BelRus and Russet Burbank potatoes which were obtained from the same source and held under the same storage conditions. At each processing date, total solids of the raw tissue were determined and the par-fries were analyzed for fat content. Samples were finish-fried and presented to panels for evaluation of sensory qualities. The color, flavor, and textural properties of frozen French fries prepared from BelRus potatoes, which were considerably higher in total solids content and absorbed less vegetable oil, were significantly preferred by sensory panels to French fries processed from Russet Burbank potatoes.     

U.S. opportunities in China’s frozen french fry market

International trade of processed potatoes, especially frozen french fry exports, has become an important part of the US potato industry. In China, one of the world’s biggest potato producing countries, consumption of US frozen french fries has significantly increased since the late 1980’s. By employing economic theory and econometric techniques, this study evaluates China’s current frozen french fry market and predicts its future development. Export demand models are developed for US frozen french fries in Greater China (Mainland China, Hong Kong, and Taiwan). The study finds that US foreign direct investment and fast food restaurants in China have great influence on the market demand for US frozen french fries. Other variables in the model include price of US frozen french fry exports, consumer income, population, price of substitutes, and trade barriers. The study forecasts that Mainland China’s frozen fry imports will exceed Taiwan and Hong Kong after year 2000. In 2005, US frozen french fry exports will increase to 227,000 tons to China, and 454,000 tons to Greater China. Although there may be some challenges, China’s market provides opportunities for the US potato industry.     

Impact of french fry length on the number of servings produced per case for quick service restaurants

The contribution of different fry length categories short (< 2 in.), medium (2 to 3 in.), and long (3 to 4 in.) and extra long (> 4 in.) to serving (individual portions) production in a “quick service restaurant” (QSR) was estimated using regression analysis with serving data developed for the purpose. The analysis provides coefficient estimates to measure serving production as a function of the number of short, medium, long, and extra long fries. The results showed significant differences between the numbers of servings produced from different length distributions. Higher proportions of longer fries produced a larger number of servings and thus produced higher serving yield per case. This study indicates greater serving production per case and potentially greater profitability for quick service restaurants that serve french fries in bags or boxes if they use fry grades with longer fry lengths.     

AC Maple Gold: A High-yielding Yellow-fleshed French Fry Cultivar

AC Maple Gold is a high-yielding oval/oblong, yellow-fleshed potato with an attractive appearance for the fresh market coupled with excellent french fry quality. The cultivar can be harvested early for french fry processing, but also maintains excellent fry quality during long-term storage. AC Maple Gold produces french fries with a uniform deep yellow color.     

Processing conditions influencing the physical properties of French fried potatoes

Summary Achieving optimal colour and texture in French fries requires careful control of the unit operations that convert the raw potatoes into fries. The effects of variation in blanching, drying and finish frying conditions on puncture properties (peak force and peak deformation) and Hunterlab L (lightness) values of French fries were investigated. Fries blanched by low-temperature long-time (LTLT) conditions had larger peak force, peak deformation and L value than fries processed by standard conditions. High-temperature short-time (HTST) blanching increased lightness but decreased peak force and peak deformation. For drying, the colour and textural quality of French fries processed by standard conditions were better than those processed by the drying alternatives. For finish frying, LTLT conditions increased peak force whereas HTST conditions increased lightness. Therefore, a compromise has to be made in processing conditions to optimise both colour and textural quality. Even after finish frying, compositional differences within potato tubers influenced texture, both between and within French fries.     

马铃薯薯条加工品质影响因素概述

主要围绕影响马铃薯薯条加工品质的因素,重点阐述了马铃薯薯条颜色、质地和丙烯酰胺含量三个方面对马铃薯薯条品质的影响。经分析发现,马铃薯品种是影响薯条加工颜色、质地和丙烯酰胺含量的决定性因素。马铃薯新品种的开发和商业化是一个漫长的过程,但将是提高薯条品质有效的方法,也会为减少丙烯酰胺含量提供有效的解决方案。     

Auxin Modulates Gibberellin-Induced Effects on Growth,Yield, and Raw Product Recovery for Frozen Processing in Potato (<Emphasis Type="Italic">Solanum tuberosum</Emphasis> L.)

Tuber shape phenotype is an important determinant of raw product (≥7.6-cm-long French fries) recovery for frozen processing. Tuber length-to-width (L/W) ratios ≥1.8 translate to maximum yield of raw product; however, some cultivars produce tubers with much lower L/W ratios. While gibberellin (GA) can be used to elongate tubers, it also decreases tuber size and can thereby attenuate raw product recovery. We investigated the utility of GA and naphthaleneacetic acid (NAA) combination treatments for modifying tuber set, size, and shape to increase yield of raw product from ‘Payette Russet’ and ‘Alturas’; two late-season frozen-processing cultivars that often produce tubers with undesirably low L/W ratios. Models describing L/W ratio and fry yield by tuber size class were developed to translate total U.S. No. 1 tuber yields (>113 g) into yield of raw product. Increases in the L/W ratios of 113–284-g tubers had a greater effect on recovery of French fries (% fresh wt) than for tubers >284 g. Undersize (<113 g) and oversize (>340 g) tubers yielded 0 and 96% fries, respectively, regardless of L/W ratio. GA applied as a seed treatment effectively hastened emergence and altered tuber shape by increasing the L/W ratios of ‘Alturas’ and ‘Payette Russet’ tubers, enhancing total fry yield for the 113–340-g tubers by 24–46%, depending on concentration and application technique (dip, spray, in-furrow). However, GA also decreased apical dominance and shifted tuber size distribution away from >284-g tubers toward higher yields of <170-g tubers, erasing the gains in fry yield when all size classes (>113 g) were considered. When combined with GA, NAA maintained apical dominance, attenuated the shift in tuber size distribution, had no effect on the GA-induced increase in tuber L/W ratio, and only partly moderated the GA-induced stimulation of plant emergence. Raw product yield from ‘Payette Russet’ increased 12–39% in spray application trials by using NAA to confine the effect of GA to tuber shape and limit the loss of U.S. No. 1 tubers to undersize. Increases in tuber L/W ratio with GA/NAA seed treatments translated to increased yield of fries only when the relative concentrations were adjusted to minimize loss of >284-g tubers and gain in undersize tubers, as dictated by cultivar sensitivity to GA. ‘Alturas’ was less sensitive to GA than ‘Payette Russet’ for shifts in tuber size distribution but not shape, resulting in 17% increase in raw product with GA alone in pre-plant seed spray application studies. GA/NAA combination treatments provide an effective approach to manipulate tuber size distribution and enhance the yield of raw product for frozen processing in cultivars with a rounder tuber shape phenotype.     

Amey: A multipurpose, russet-skinned potato cultivar for the Eastern United States

Amey is a late-maturing, russet-skinned, whitefleshed potato cultivar that yields more than Russet Burbank in most eastern United States potato production areas. Tubers of Amey are mostly oblong, occasionally long, with an evenly russetted skin. Tubers of Amey are smoother, more attractive, and have a much lower incidence of external defects than Russet Burbank. The specific gravity of Amey is equal to or greater than the specific gravity of Russet Burbank. French fries produced from Amey are lighter than or equal in color to those produced from Russet Burbank; however, tubers are frequently not long enough to satisfy the french fry industry. Baking and taste quality of Amey are excellent, and it has potential as a fresh market potato. Amey is resistant to race Rol of the golden nematode, powdery scab, and common scab. It is moderately susceptible to Verticillium wilt. It is susceptible to potato leafroll virus, late blight, and early blight.     

Oil content of French fries as affected by blanch temperatures,fry temperatures and melting point of frying oils

The oil content of par-fried frozen French fries prepared by two methods, conventional and freeze-leached, was not affected by blanch temperatures when blanched for 15 minutes. Melting points of the frying oil did affect the oil content of par-fried French fries. The differences were variable and could not be explained by melting point alone. Blowing the potato strips with ambient air after the par-fry and cooling below the melting point of the frying oil had no effect on the oil content of the frozen product. Contrary to previous reports, the oil content of the French fries increased significantly as the par-frying temperature was increased from 160.0 to 185°C (320 to 365°F) with the greatest increase occurring between 171.1 and 185.0°C (340 and 365°F). The French fries par-fried 1 min at 171.1 and 185.0°C (340 and 365°F) were judged to have identical quality after finish frying 3 minutes at 185.0°C (365°F). A lower par-fry temperature or possibly a shorter par-fry time at the higher temperature would be an advantage to the processor who could use less oil and energy without adversely affecting the quality of the final consumable product.     

Payette Russet: a Dual-Purpose Potato Cultivar with Cold-Sweetening Resistance,Low Acrylamide Formation,and Resistance to Late Blight and Potato Virus Y

Payette Russet is a full season, russet-skinned potato cultivar notable for its cold-sweetening resistance and associated low acrylamide formation, making it ideally suited for processing into French fries and other potato products. Low asparagine and reducing sugar concentrations in Payette Russet tubers contribute to an 81 % reduction in acrylamide content in French fries relative to cultivars Ranger Russet and Russet Burbank following eight months storage at 9 °C. In three years of evaluations in the Western Regional Potato Variety Trials, average yield of Payette Russet was intermediate between Ranger Russet and Russet Burbank, but Payette Russet had the highest U.S. No. 1 yield when averaged across all eight trial locations. Acceptably low tuber glucose concentrations (<0.10 % glucose FWB) were maintained in Payette Russet following up to nine months storage at temperatures as low as 5.6 °C with consistently acceptable French fry color scores obtained (USDA value ≤2.0). Reducing sugars are also maintained uniformly throughout Payette Russet tubers, resulting in a low incidence of sugar ends and reduced mottling in French fries relative to standard processing cultivars. Long tuber dormancy also benefits long-term storage for processing. With its russet skin, Payette Russet could also be used for fresh-pack, and its assemblage of disease resistances makes it especially suitable for organic production, or for use by growers and companies seeking greater sustainability in their production. Payette Russet is resistant to foliar and tuber late blight, common scab, and has extreme resistance to PVY conferred by the presence of the Rysto resistance gene. Payette Russet also has a moderate level of resistance to Verticillium wilt, early blight, and corky ringspot. It is susceptible to Fusarium dry rot (F. sambucinum), therefore production and storage management guidelines are provided to minimize tuber infection. Payette Russet displays a low incidence of second growth and growth cracks, especially relative to Russet Burbank, and is intermediate between Ranger Russet and Russet Burbank for incidence of hollow heart/brown center. Blackspot bruise expression for Payette Russet is similar to Russet Burbank and reduced relative to Ranger Russet. Payette Russet was more susceptible to shatter bruise, internal brown spot, and tuber weight loss in storage relative to the industry standard cultivars. Payette Russet was released in 2015 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington, and is a product of the Northwest (Tri-State) Potato Variety Development Program.     

Suitability of Organic Potatoes for Industrial Processing: Effect of Agronomical Measures on Selected Quality Parameters at Harvest and after Storage

Three factorial field experiments were conducted in two consecutive years (2003 and 2004) on two sites in order to examine the impact of preceding crop, pre-sprouting, N and K fertilization and cultivar on quality attributes of organically grown potatoes destined for processing into French fries or crisps. Tuber dry matter (DM) concentration, glucose and fructose concentrations, as well as the colour of crisps and the quality score of French fries, were assessed at harvest and after a 4-month storage period. Results suggest that tubers from organic potato cropping may be expected to have sufficiently high tuber DM concentrations (>19%) for processing into French fries without impairing the texture of the fries when concentrations exceed 23%. DM concentrations of tubers for crips (cv. Marlen) fell short of the required minimum of 22% when a combined N and K fertilizer was applied. The tuber DM concentration was significantly lower following peas than following a legume-grass/clover ley or cereals (oats or winter wheat), but only in one of two seasons. Pre-sprouting increased tuber DM concentration considerably, especially in the growing season with a high incidence of Phytophthora infestans (+1.2% absolute increase). Tuber DM concentration was significantly higher after storage in two of three experiments (+0.4 and 0.5% absolute increase). Cultivars belonging to the very early and early maturity type showed the largest relative increase in reducing sugars concentrations due to storage, ranging between 300 and 1,100%. The medium-early cv. Agria and medium-late cv. Marena proved to be best suited for processing into French fries under conditions of organic farming, as only minor deviations from the highest quality standards were established at harvest (quality index at 4.3 and 4.1, respectively). A consistently high crisp quality was achieved by the medium-early cv. Marlen, with L-values of 70.8 and 66.7 at harvest and after storage, respectively. Overall, results show that the quality variables were mainly affected by cultivar, season, storage and their interaction. The effect of agronomical measures, such as fertilization, preceding crop and pre-sprouting of seed-tubers, was rather small and their effect on internal tuber quality and quality of fried products may hardly be predictable. The quality standards for tuber raw stock can be accomplished best when adequate cultivars are chosen.     

Benchmarking Local Potato Processing in Developing Countries: The Case of French Fries in Lima,Peru

Declining tariffs and exchange rate appreciation have raised concerns about the competitive position of local potato processors in developing countries. Yet, relatively little is known about these processors, their competitiveness under current market conditions, how that might change with future tariff reductions or shifts in exchange rates, or what might be done to improve their efficiency over time. This study focuses on the market for French fries in Lima, Peru. Estimates based on field work carried out among local, small-scale processors indicate that locally made, peeled and cut fresh potatoes cost considerably less than imported, industrial-scale, frozen French fries under various tariff and exchange rate scenarios. A series of recommendations are put forward to continue to improve the efficiency of local processors and the quality of their finished product as well as some topics for future research.     

Determination of disodium acid pyrophosphate in French-fried potatoes

An analysis procedure was developed to determine residual disodium acid pyrophosphate (SAPP) in French-fry strips after treatment. The uptake of SAPP in relation to concentrations and temperatures of the treating solution, lengths of treating time and loss of P₂O₇ from the finish-fried French fries are also considered.     

Acrylamide Formation in Processed Potatoes as Affected by Cultivar,Nitrogen Fertilization and Storage Time

The affirmation of acrylamide as a probable carcinogen by the European Food Safety Authority has reinforced the need to lower acrylamide content in fried potato products. Selected for low reducing sugars and acrylamide-forming potential, recently released cultivars ‘Alpine Russet’, ‘Dakota Trailblazer’, and ‘Ivory Crisp’ were evaluated for their processing quality when grown with varying nitrogen (N) fertilizer regimes. The objective of this study was to determine the effects of N fertilizer rate (34, 135, 202, 269 and 336 kg ha^?1) on tuber glucose and acrylamide concentration following processing of new cultivars relative to standard cultivars ‘Russet Burbank’ and ‘Snowden’ at harvest, and after 3, 6 and 9 months of storage at 7.2 °C over 2 years. Glucose and acrylamide responses to N rate were similar for chip cultivars, which linearly decreased in 2011, and quadratically increased then decreased in 2012 with increasing N rate. The N rate effect on French fry glucose concentration varied by cultivar and either decreased or did not respond to elevated N rate. Glucose and acrylamide concentrations of chip cultivars generally increased during storage, with a dramatic increase in ‘Snowden’ resulting from senescence sweetening after 9 months of storage. Environmental conditions significantly affected glucose and acrylamide responses of French fry cultivars to storage time. Glucose and acrylamide concentrations of all French fry cultivars generally increased during storage in 2011. In contrast, glucose concentrations of French fry cultivars were stable or increased, while acrylamide concentrations generally decreased during storage in 2012. The relationship between chip color and glucose concentration was significant, but differed by year. Glucose and acrylamide concentrations of French fry and chip cultivars were significantly correlated (R²?=?0.52 and 0.66, in 2011 and 2012, respectively). Generally, acrylamide in fried potato products can be minimized by using low reducing sugar cultivars supplied with a N fertilizer rate that optimizes yield and quality during growing seasons with minimal environmental stress.     

Teton Russet: An Early-Maturing,Dual-Purpose Potato Cultivar Having Higher Protein and Vitamin C Content,Low Asparagine,and Resistances to Common Scab and Fusarium Dry Rot

Teton Russet is an early-maturing, medium-russeted, potato cultivar with high merit for both fresh-pack and processing. In early harvest trials in the Pacific Northwest, Teton Russet had total yields similar to Russet Norkotah, and higher than Ranger Russet and Russet Burbank. Marketable yield of Teton Russet in the early harvest trials was also comparable to or higher than Russet Norkotah in Washington and Oregon, and higher than Ranger Russet and Russet Burbank at these sites, as well as in Idaho. In full-season trials, while total yield of the earlier-maturing Teton Russet tended to be lower than Ranger Russet and Russet Burbank, marketable yield was generally higher than Russet Burbank across the majority of sites due to its higher percentage of U.S. No. 1 tubers. Teton Russet is suitable for processing, with acceptable fry color following up to 8 months of storage at 8.9 °C. Uniformity of fry color was also very consistent. Teton Russet has shown lower levels of the amino acid asparagine relative to Ranger Russet and Russet Burbank which may contribute to lower acrylamide levels in French fries and other processed potato products. Teton Russet is notable for having resistance to common scab (Streptomyces spp.) and Fusarium dry rot, and is moderately resistant to tuber net necrosis. Analyses have also shown Teton Russet to have significantly higher protein levels than Russet Norkotah, Ranger Russet, and Russet Burbank, as well as higher vitamin C content than Russet Norkotah and Russet Burbank. Teton Russet was released in 2011 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington, and is a product of the Pacific Northwest Potato Variety (Tri-State) Development Program.     

Relationships between fry color and sugar concentration in stored Russet Burbank and Shepody potatoes

Relationships between french fry color and sugar composition of Russet Burbank and Shepody potatoes harvested at various chemical maturities (i.e., sucrose concentrations) and exposed to various temperature regimes during 8 to 9 months storage were examined. Combined data from 3 years of study showed fry color to be more closely associated with glucose during 8 C storage for Russet Burbank (r²=0.65) and Shepody (r²=0.62) than with fructose, total reducing sugars, sucrose, or total sugars. Glucose > 1.6 mg g^?1 in Russet Burbank and > 1.2 mg g^?1 in Shepody resulted in fries which were too dark to be eligible for maximum bonus paid by processors for good color. Russet Burbank harvested with sucrose > 3.1 mg g^?1 and Shepody harvested with sucrose > 1.6 mg g^?1 and preconditioned for 14 d at 15 C before storage at 8 C accumulated enough glucose in storage to result in fries which were darker than was acceptable for maximum bonus payment. Preconditioning at 15 C for 70 d was necessary to prevent Russet Burbank with sucrose of 3.9 mg g^?1 at harvest from accumulating unacceptably high glucose during storage. Glucose determined with enzymatic test strips was in close agreement with that by HPLC for both cultivars. The test strips could be used to estimate fry color of Russet Burbank.