The effects of ozone and 1,8-cineole on sprouting,fry color and sugars of stored Russet Burbank potatoes

Ozone and 1,8-cineole were investigated as alternatives to isopropyl-n-(3-chloro-phenyl)carbamate (CIPC) to control sprout development of potato (Solatium tuberosum) tubers cv Russet Burbank during long-term storage. Sprout development was similar in ozone-treated and air-stored tubers, but both had much larger and more numerous sprouts than CIPC-treated tubers. Sucrose and reducing sugars in ozone-treated tubers were similar to levels in air-stored potatoes. Fry color was not different among potatoes stored in ozone, air and CIPC. Conversely, potatoes treated with 1,8-cineole did not produce any sprouts during the 25 week study. The fry color of tubers exposed to cineole was darker than either air-stored or CIPC-treated tubers. Sucrose and reducing sugar levels were higher in cineole-treated tubers than in tubers treated with CIPC.     

Effect of CIPC [Isopropyl-N(3-chlorophenyl)carbamate] on total nitrogen content and polyphenol oxidase activity in relation to processing of potatoes (Solanum tuberosum L.) stored under different conditions

Two varieties of potatoes viz. Kufri Chandramukhi and Kufri Sindhuri were treated with Isopropyl-N(3-chlorophenyl)carbamate at two different concentrations viz. 4000 and 5000 ppm. The treated potatoes were stored for a period of four months under different storage conditions i.e. room temperature, cold and evaporative cooling chamber storage and analysed for polyphenol oxidase activity, total nitrogen content and quality of dried slices produced from these at different stages of storage. Higher nitrogen content was observed in CIPC treated potatoes as compared to control. Polyphenol oxidase activity decreased more in Kufri Chandramukhi than in Kufri Sindhuri in CIPC treated as well as in control experiments. The changes in nitrogen content and polyphenol oxidase activity were more pronounced in evaporating cooling chamber and in room storage than in the cold storage. The quality of potato slices prepared from both varieties confirmed the superiority of Kufri Chandramukhi over Kufri Sindhuri for processing purposes.     

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.     

Comparison of sensory differences of stored Russet Burbank potatoes treated with CIPC and alternative sprout inhibitors

The sensory properties of Russet Burbank potatoes treated with three naturally occurring volatile compounds, as alternatives to CIPC for sprout inhibition, were evaluated. Potatoes from the 1995 and 1996 crop years were treated with salicylaldehyde, 1,8-cineole, 1,4-dimethylnaphthalene, or CIPC prior to dormancy break during storage and stored for up to 16 wk. Sensory differences between potatoes treated with alternative sprout inhibitors and CIPC-treated or untreated potatoes and inhibitor concentration were determined at 2-wk intervals. Potatoes treated with 1,8-cineole or salicylaldehyde, but not 1,4-dimethylnaphthalene, were significantly different from the untreated potatoes or potatoes treated with CIPC. Sensory detection threshold levels for the alternative inhibitors were measured in a model potato system. The residual levels of the sprout inhibitors were within the detection threshold range for 1,8-cineole (0.02–0.04 ppm), but not for salicylaldehyde (0.0–0.10 ppm) or 1,4-dimethylnaphthalene (0.80–1.40 ppm). The presence of the residual sprout inhibitors and/or the influence of sprout inhibitors on potato metabolism during storage contributed to observed differences in sensory quality of stored potatoes.     

CIPC residues on stored Russet Burbank potatoes: 1. Maximum label application

Residue concentrations of chlorpropham (CIPC) on stored Russet Burbank potatoes were evaluated after thermal aerosol treatment at maximum labeled rates. The aerosol was applied after the potatoes had been placed in the storage structure and the wound healing process was complete. Average residue concentrations four days after the initial application ranged from 6 to 8 mg/kg fresh tuber weight depending on the storage temperature and the application rates. A second aerosol treatment applied 90 days after the first treatment kept the residue concentrations above 5 mg/kg for the duration of the storage period. A direct spray application to the tubers at various times during the study raised the average CIPC concentration an additional 2 to 3 mg/kg. All CIPC residue concentrations measured on tubers in this study were below the EPA established (1996) tolerance of 30 mg/kg. Residue concentrations of CIPC were greater on potatoes near the bottom of the pile than near the top of the pile. These variations in CIPC residue concentrations (3–8 mg/kg between top and bottom of the bulk pile) are appropriate justification for the development of improved application methodology.     

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.     

Isopropyl N-(3-chlorophenyl) Carbamate (CIPC) Residues in Potatoes Stored in Commercial Cold Stores in India

Since no attempt has been made so far in India to determine isopropyl N-(3-chlorophenyl) carbamate (CIPC) residues in potatoes, it became necessary to determine its residues in potatoes which are being used for table and processing purposes. Using high-performance liquid chromatography, CIPC residues were determined in peels, peeled tubers and unpeeled tubers periodically during storage at 10–12 °C in commercial cold stores. The highest concentration of CIPC found in potato peels was 20.17 mg/kg fresh wt, whereas in unpeeled and peeled tubers the residue levels were very low ranging from 0.29 to 1.13 and 0.05 to 0.24 mg/kg, respectively. However, all residue levels observed were within the maximum residue level prescribed by the US Environmental Protection Agency. The experiments done to determine the dispersal and concentration of CIPC applied as an aerosol fog with respect to location and time showed that the distribution of CIPC within the cold store was uneven leading to large variations in residue levels in samples drawn from different parts of the store.     

Disease and sprout control in individually film wrapped potatoes

Potatoes (Solanum tuberosum L. cv Russet Burbank) were individually wrapped in Cryovac D-955, a biaxially oriented shrink film, and stored at 24°C. The wrapped potatoes were either treated with a fungicide (thiobendazole), or the film itself was coated with an antimicrobial agent (silicon quaternary ammonium salt) to control diseases that may appear during storage and marketing. Under film wrapped conditions, disease control using a fungicide or antimicrobial agent was not completely successful; however, the marketable qualities of the potatoes were not affected. Disease spread under film wrapped conditions was minimized if the potatoes were disinfected in chlorine (0.5% sodium hypochlorite) and wrapped after they were dried. In another study dormant and post-dormant potatoes were individually film wrapped after they were treated with maleic hydrazide (MH) (pre-harvest treatment) or isopropyl N-(3-chlorophenyl) carbamate (CIPC) (postharvest treatment) for sprout control. Under film wrapped conditions, MH decreased sprouting in the dormant potatoes but not in the post-dormant potatoes. CIPC inhibited sprouting in the post-dormant film wrapped potatoes but was less effective in the dormant potatoes.     

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.     

CIPC and 2,6-DIPN sprout suppression of stored potatoes

A five-year storage season study using small-scale bins was undertaken to determine the effectiveness of 2,6-diisopropylnaphthlene (2,6-DIPN) in combination with isopropyl-N-(3-chlorophenyl)carbamate (CIPC) for sprout suppression of stored potatoes (Solanum tuberosum L.). The study environment simulated a commercial operation and the storage bins held up to 4,500 kg of tubers. Russet Burbank potatoes were tested for four storage seasons, and for one season the bin space was split between Ranger Russet and Snowden potatoes. Sprout suppression was measured as percent acceptable for fresh pack (%AFP), defined as sprouts ≤3 mm in length. When 2,6-DIPN was used alone at 8.3 mg kg^-1 fw, it only provided short-term sprout suppression. Sprout suppression responses for the two chemicals were similar for Russet Burbank, Snowden and Ranger Russet. When 2,6-DIPN was used in combination with CIPC, a significant increase in sprout suppression was observed. In addition, when the two chemicals were used in combination, the amount of CIPC could be reduced by as much as 50% while still maintaining equal or better sprout suppression as compared to CIPC alone. For overall long-term sprout suppression, the best treatment was a combination of CIPC and 2,6-DIPN, each at 16.6 mg kg^-1.     

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.     

Respiration studies on Russet Burbank potato tubers: Effects of storage temperature and chemical treatments

Tubers of Russet Burbank potatoes were stored at 36 F (2.2 C), 42 F (5.6 C), 45 F (7.2 C), 48 F (8:9 C), and 70 F (21.1 C) and respiration rates determined. Chemical treatments 4 with growth regulators were made and respiration rates determined on intact tubers. Tubers stored 42 F (5.6 C) and 45 F (7.2 C) generally respired less and at a more uniform rate than tubers stored at other temperatures. The respiration rate of CIPC and BA (20 ppm) treated tubers was less than the untreated tubers.     

Potato sprout inhibition and tuber quality after treatment with high-energy ionizing radiation

The use of industrial-type linear accelerators may be an alternative treatment for controlling sprouts in potatoes during long-term storage. The technical aspect of treatment has been described and may include largescale treatment of bulk potatoes as they are moving along a system of conveyors either to or from storage. The objective of the study was to evaluate the use of a linear accelerator for long-term sprout control under commercial storage conditions and the effects on tuber quality. An 18-MeV linear accelerator was used to provide sprout-inhibiting irradiation to various lots of ‘Russet Burbank’ potatoes. Successful sprout suppression was achieved with doses of 40 to 50 Gy (0 g sprout weight after 9 months of storage at 7.2 C) while higher doses caused undesirable increases in reducing sugars in the tubers. Glucose concentrations of treated tubers (0.25% fresh tuber weight) were higher after treatment than the untreated controls (0.08%), but returned to control levels after 2 to 6 months in storage. Glucose concentrations in treated tubers were significantly reduced with storage management for reconditioning by increasing the storage temperature for one month (from 7.2 C to 14.4 C) resulting in glucose concentrations near control concentrations. By increasing the dose-rate from the accelerator, recovery of tuber glucose concentration due to radiation treatments was significantly faster than when the dose was given more slowly. Potato tubers irradiated with high rates (100 Gy) of high-energy electrons exhibited an increase in soft rot and dry rot incidence in storage. Disease development in potatoes treated with sprout inhibiting doses of radiation (50 Gy) increased in lots with a high rot potential. Treated lots with low rot potential were successfully stored for 8 months or more without an increase in rot potential or shrinkage. Selection of lots for irradiation treatment should include some preliminary evaluation for development of disease in long-term storage.     

Effect of tetrachloronitrobenzene (fusarex) on emergence and yield of potatoes. Part III. — Northeast

Foundation seed potatoes of Katahdin, Kennebec and Pungo varieties were treated with Fusarex dust at three dates during the 1966–67 storage season. In 1967 these treated seed potatoes were planted in uniform tests and compared with untreated and desprouted seed potatoes. Cooperators in Maine, Long Island, New Jersey, Pennsylvania and Connecticut planted the seed lots, recorded plant emergence, and obtained yield data. Initial emergence of Fusarex-treated and desprouted seed was delayed when compared with untreated seed except in Pennsylvania where both initial and final emergence of Pungo and Kennebec was improved by Fusarex treatment. Final emergence of January and March Fusarextreated seed of all three varieties was better than that of untreated and desprouted seed in Pennsylvania. At all other locations improvement of plant stand by Fusarex seed treatment was very erratic. The March Fusarex treatments resulted in an average yield equal to the untreated seed. Yield of tubers from chemically treated Katahdin seed was not significantly affected when compared with untreated seed at four of the five locations. November treatment of Kennebec seed with Fusarex adversely affected yields at three of the five locations. In Connecticut all Fusarex seed treatments reduced yields of Kennebec. Pungo seed treated with Fusarex produced yields in most cases that were not statistically higher than that of untreated seed.     

Sugar-Starch Metabolism and Antioxidant Potential in Potato Tubers in Response to Different Antisprouting Agents During Storage

Single applications of different antisprouting agents like hot water treatment, spearmint oil and clove oil were carried out on potato cultivar “Lady Rosetta” to compare their efficacy with that of synthetic chloro isopropyl N-phenyl carbamate (CIPC). The tubers were stored at ambient storage conditions (25?±?2 °C) for 81 days to assess changes in their sugar-starch concentrations and antioxidant potential. Antioxidant potential in the tubers was assessed as their total phenolic concentrations and radical scavenging activities. In addition, the enzymatic activities were also determined in order to evaluate the possible depletion of these antioxidants as substrate during storage. Results revealed significant response of stored potatoes to all antisprouting agents compared with the control (P?≤?0.05). CIPC and clove oil applications maintained tuber dormancy almost twice as long (81 days) as observed in the control (45 days). Application of spearmint oil and hot water treatment maintained tuber dormancy for almost 2 months. However, it was associated with an increased percentage sprouting during the last weeks of storage. At the end of storage, the highest starch (16.83%) and lowest sugar (0.99%) concentrations were estimated after CIPC application and maximum total phenolic concentration (143.57 mg gallic acid equivalent (GAE)/100 g), and highest antioxidant activity (39.73%) were found after clove oil application. Enzymatic activities were not statistically different between CIPC and clove oil application during most of the storage period. Results showed that efficient replacement of CIPC with clove oil in the premium potato cultivar might be useful; this may avert related food safety and environmental issues and would also ensure organic potato storage.     

Persistence of Chlorpropham (CIPC) in the Concrete Flooring of Potato Stores

The loss of the sprout suppressant, chlorpropham (CIPC), to the fabric of potato stores is currently of concern due to the risk of potential cross contamination of other crops subsequently housed in these stores. HPLC UV/VIS and GCMS methods were successfully employed to detect CIPC in the concrete flooring of research and commercial potato stores with histories of between 1 and 26 years of use. The concentrations in identical research stores, with different numbers of applications, were in the range 0.58–5.7 and 3.4–112 μg g^?1, suggesting the magnitude of contamination was influenced by the number of applications. Commercial store A, with a history of 18 seasons of applications (estimate of total CIPC applied 2040 kg), had concentrations varying between 6 and 48 μg g^?1 in the top three centimetres, with more than 92% within the top centimetre. In contrast, commercial store B, with a history of less than five seasons of applications (estimate of total CIPC applied 319 kg), had concentrations varying between 0.58 and 304 μg g^?1 in the top four centimetres, with less than 47% within the top centimetre. The difference in depth distributions between A and B may be due to the structural integrity of the concrete, which was much poorer in B. CIPC was persistent in all stores irrespective of the total quantities of CIPC applied and date of the final application.     

Sprout inhibition in storage: Current status, new chemistries and natural compounds

A major component of managing potato quality in storage is effective sprout inhibition. Sprouting causes increased weight loss, reduced tuber quality and impedes air movement through the potato pile. The primary method to control sprouting in storage is with postharvest applications of isopropylN-(3-chlorophenyl) carbamate (chlorpropham; CIPC). CIPC inhibits sprout development by interfering with cell division. However, a recent Environmental Protection Agency mandate, from the requirements of the Food Quality Protection Act (FQPA) of 1996, resulted in a reduction in allowable CIPC residue on fresh potatoes in the United States from 50 ppm to 30 ppm. This mandate coincides with tolerance reductions or restrictions for use of CIPC in other parts of the world. CIPC is an effective sprout inhibitor although factors such as storage conditions, application technology, and cultivar can impact that effectiveness. Alternative sprout inhibitors to CIPC continue to be evaluated. Essential oils (e.g., caraway, peppermint, spearmint, clove) or their components (e.g., s-carvone, eugenol), and hydrogen peroxide-based materials, physically damage the developing sprout and suppress sprout elongation. However, repeated or continuous application of these compounds may be necessary for efficacy. Substituted naphthalenes (e.g., dimethyl naphthalene, diisopropyl naphthalene) may help reduce the amount of CIPC applied and/or our dependency on CIPC for sprout suppression in storage. The objective of this review is to summarize the current use of CIPC for potato sprout inhibition in storage and to review the status of current research on other postharvest applied compounds or materials that may be used as alternatives for CIPC.     

Gas chromatographic studies on the suitability of irradiated potatoes for storage and processing

Summary In two series of experiments, batches of potatoes, some treated by irradiation and some with chemical sprout inhibitors, were processed into chips on an industrial scale after 7–8 months of storage. The quality of the chips and of the stored fresh potatoes was related to gas chromatographic analyses of sugar and acid contents. It was found that only the irradiated potatoes in which the content of fructose and glucose at the time of processing amounted to not more than 0.07% each of the fresh weight, yielded marketable chips of good quality. If the concentrations of reducing sugars were as low as this, then the rate of rotting was also very low, even in the irradiated batches. Shipment of the potatoes by truck over a distance of approximately 300 km after irradiation had no detectable deleterious effect.     

Changes in chlorpropham residues in stored potatoes

Chlorpropham (CIPC)³ concentrations were measured in peel samples of tubers taken from large commercial potato storages and from test bins after aerosol application. Tuber samples were taken at different levels within the pile and at numerous sites near the surface. The minimum concentration of CIPC in the peel layer for complete inhibition of sprouting was estimated to be 20 ppm. Immediately after commercial application of CIPC, 99% of the sample sites had concentrations high enough to completely inhibit sprouting, and residues in the peel were generally highest in samples obtained from the surface and from the bottom of the pile. CIPC concentrations decreased during the storage season in nearly all sites tested. Storages differed in the rate at which CIPC was lost. Mean peel residues fell below the level necessary for sprout inhibition in some storages but not in others. The rate of CIPC loss increased at the same time that air movement to maintain the desired temperature increased. With the 20 ppm threshold level as a guide, it is possible to monitor commercial storages for sprout-inhibition status. Retreatment before peel residues drop below 20 ppm can extend sprout inhibition in storage.     

Effect of fumigation of potato seed tubers with 2-aminobutane on plant growth and yield

From 1968 to 1973, 13 field experiments were carried out to discover any effects of fumigation of seed tubers with 2-aminobutane (used for tuber disease control) on subsequent plant growth and yield. Nine experiments were done with tubers treated within 1 month of harvest, the remaining 4 with tubers stored for several months before treatment. In general, fumigation did not have any substantial effect on the growth pattern or the yield of the crop obtained from treated seed, although in most cases it was probable that there were small increases in the number of sprouting eyes, percentage emergence, stem number and in weight and number of seed tubers at harvest. However, these effects rarely reached levels which gave a statistically significant increase over crops grown from untreated material.