Isopropyl N-(3-chlorophenyl) Carbarmate (CIPC) Effect on Nitrogenous Constituents of Potatoes

Potatoes treated with 1% or 3% CIPC and stored 16 weeks at 5°C and 20°C were analyzed for nitrogenous constituents. Treatment with 1% CIPC significantly (p < 0.025) increased total nitrogen and protein content in tubers of two cultivars compared to untreated control tubers following storage at 5°C and 20°C. Treatment with 3% CIPC increased total nitrogen and decreased protein in tubers stored at 20°C (p < 0.025), but decreased total nitrogen and protein in tubers stored at 5°C. Treating potatoes with CIPC prevented sprouting in both varieties and apparently caused the tuber to retain nitrogen.     

Effect of Irradiation on Discoloration, Phenols and Lipids of Potatoes

The effect of two irradiation doses, 10 and 100 krad, on discoloration, phenolic content and lipid content of Katahdin and Russet Burbank potatoes was studied. Potatoes were stored 1, 4 and 26 wk at 5°C and 20°C following irradiation. Irradiation increased discoloration and phenols and decreased crude lipids and the phospholipids. Potatoes receiving 100 krad dose discolored more, were higher in phenols, and lower in lipids than those given 10 krad dose. Potatoes stored at 5°C discolored more and were higher in phenols and in lipids than those stored at 20°C. Increased storage at both temperatures resulted in greater discoloration, increased phenolic content and decreased lipids content.     

Moist and Dry Heat Reduce Isopropyl N-(3-Chlorophenyl) Carbamate (CIPC) Residue in Potatoes

Moist (boiling and pressure-cooking) and dry heat (baking with and without foil, and microwaving) were compared as to their effect on CIPC retention in potatoes. Tubers were dipped in a 1% emulsion of CIPC for 5 min. prior to processing and stored at 5°C for 0, 1 and 2 mo. All processing methods significantly (p<0.01) reduced CIPC residue in potatoes. Moist heat methods reduced CIPC more than dry heat. Boiling resulted in significantly (p<0.01) greater reduction of CIPC than pressure-cooking while baking without foil resulted in greatest reduction of CIPC followed by microwaving and baking with foil. The peel localized 20 times more CIPC residue than the cortex.     

EFFECT OF PACKAGING MATERIAL ON THE QUALITY OF POTATOES TREATED WITH ISOPROPYL N-(3-CHLOROPHENYL) CARBAMATE (CIPC)

Katahdin and Russet Burbank potatoes, treated with isopropyl N-3(-chlorophenl) carbamate CIPC and stored for four months at 5C in either mesh or polyethylene bags (two packaging materials frequently used for potato storage), were tested for enzymatic discoloration, phenolic and ascorbic acid concentration. CIPC residues in tubers stored in polyethylene bags were significantly (p < 0.0l) higher than those stored in mesh bags. Tubers stored in polyethylene showed significantly (p<0.05) higher discoloration and phenolic concentration, and lower ascorbic acid concentration than those stored in mesh bags. Differences in CIPC retention of the tubers stored in the two packaging materials may have been responsible for some of the differences in quality factors since CIPC was shown to significantly (p<0.0l) increase the enzymatic discoloration and phenolic concentration, and decrease the ascorbic acid concentration of both cultivars.     

Changes in Total Phenolic, Total Glycoalkaloid, and Ascorbic Acid Content of Potatoes as a Result of Bruising

The effect of bruising on total phenols, total glycoal/kaloids (TGA), and ascorbic acid content of Katahdin potatoes was studied. Following bruising, tubers were stored at either 5° or 20°C for I, 3, 6, and I2 wk. Unbruised whole tubers served as controls and bruised halves were compared with unbruised halves. Both halves of bruised tubers were higher in phenols, TGA and lower in ascorbic acid than unbruised controls. Bruised halves contained significantly more phenols, TGA and less ascorbic acid than unbruised halves. Storage temperature did not affect ascorbic acid content but the greatest accumulation of phenols occurred at 5°C and the highest TGA at 20°C storage temperature. Cortex tissue was significantly lower in ascorbic acid than pith tissue.     

Effect of Irradiation on Total Glycoalkaloids in Kennebec and Russet Burbank Potatoes

Effect of irradiation and storage conditions following irradiation on total glycoalkaloids (TGA) of Russet Burbank and Kennebec potatoes stored 4 and 12 wk was investigated. TGA increased significantly (p < 0.005) immediately following irradiation in both cultivars, but decreased upon storage. TGA was higher in Kennebec than Russet Burbank often exceeding levels considered safe for human consumption. At 5°C TGA was higher in tubers stored in paper as compared to polyethylene, while at 20°C this was reversed.     

Effects of traditional storage practices of small‐scale organic farmers on potato quality

A study was undertaken to investigate the effect of traditional storage practices of small‐scale organic farmers in rural KwaZulu–Natal on the quality of potatoes. Changes in sugar and starch content were monitored. A preference ranking test was used to investigate preference for organically produced potatoes left in situ, stored under ambient conditions in a farmer's house and under controlled conditions (7 °C and 90% relative humidity) for 2, 4 and 6 weeks. The lowest and highest sugar levels were observed in potatoes stored in situ and under controlled conditions, respectively. Potatoes stored in situ were significantly preferred by sensory panellists (P < 0.05) over those stored in both the farmer's house and in controlled storage. Preference rank scores were negatively correlated to total sugar content and positively correlated to starch content although not all correlations were statistically significant. This gives an indication that other factors not investigated in this study, like glycoalkaloid content, may have contributed to the acceptability of potatoes from different modes of storage and requires further investigation. However, the study clearly shows that leaving potatoes in situ as a method of storage maintains desirable sensory properties of potatoes by maintaining low sugar levels and higher starch content. Copyright © 2007 Society of Chemical Industry     

Variety and storage conditions affect the precursor content and amount of acrylamide in potato crisps

BACKGROUND: Acrylamide, a probable human carcinogen, is formed from the amino acid asparagine and reducing sugars when potato products are processed at high temperatures. This is a two‐year study on five Swedish‐grown potato clones, two of which are adapted to cold storage. The clones represented a wide range of precursor concentrations: asparagine, 3.7–15.3 mg g^?1; reducing sugars, 0.9–14.9 mg g^?1. Crisps were prepared in laboratory‐scale equipment mimicking industrial processing conditions. RESULTS: Potatoes stored at 4 °C had significantly higher levels of glucose and fructose than potatoes stored at 8 °C. Acrylamide levels were significantly higher in crisps made from potatoes stored at 4 °C. Two clones with a large difference in asparagine concentration but similar glucose and fructose concentrations gave crisps with significantly different acrylamide contents. The lowest levels of acrylamide were found in crisps made from the potato variety with the lowest asparagine concentration. CONCLUSION: The findings show that variety and storage conditions influence the levels of precursors. Acrylamide formation in crisps can be reduced by using potato varieties with low levels of both asparagine and reducing sugars. Mass transport of precursors during heating is suggested to be important for acrylamide formation in potato crisps. Copyright © 2007 Society of Chemical Industry     

Sugars and Free Amino Acids in Stored Russet Burbank Potatoes Treated with CIPC and Alternative Sprout Inhibitors

Glucose, fructose, sucrose and free amino acids were measured in stored Russet Burbank potatoes treated with sprout inhibitors isopropyl-N-(3-chlorophenyl) carbamate (CIPC), 1,4-dimethylnaphthalene (DMN), cineole and salicylaldehyde. Storage effects on sugar and amino acid contents were dependent on the specific sprout inhibitor. Salicylaldehyde treatment (200 ppm) produced a rapid increase of reducing sugar content and a greater amount of free amino acids than other treatments. A smaller amount of tyrosine was found in DMN (40 ppm) treated tubers compared to all other treatments. After 16 wk at 7°C, all potatoes treated with inhibitors had 10.5–11.8 mg/g dry weight reducing sugar content which would be considered acceptable for French fry processing.     

Effect of Packaging Material on Nitrate Nitrogen Content of Irradiated Potatoes

The effect of packaging materials on nitrate nitrogen content of irradiated potatoes was investigated. Tubers were irradiated at 10, 30 and 100 Krads and stored for 12 wk at 5°C in paper or plastic bags. Nitrate nitrogen content was significantly (p < 0.01) higher in tubers packaged in plastic as compared to those in paper bags. Irradiation significantly (p < 0.01) increased nitrate nitrogen content between the lowest and highest levels of treatment in tubers stored in both paper and plastic bags.     

The influence of French fries processing on the glycoalkaloid content in coloured-fleshed potatoes

French fries made from coloured-fleshed potatoes may be interesting alternative to the traditional snacks for consumers. However, potatoes contain glycoalkaloids (TGA), so potato tubers and obtained fried snacks should be subjected to comprehensive examination. The aim of this study was to determine the effect of different stages of French fries processing on the content of TGA (α-solanine and α-chaconine) in the red- and blue-fleshed potatoes, in semi-products and ready-to-eat products. It was stated that during the processing of French fries prepared from coloured-flesh potato varieties significantly decreased the content of TGA (α-solanine and α-chaconine) in the samples obtained at different stages of the process compared to the raw material. Potatoes with blue-fleshed of Vitelotte variety and red-fleshed of Highland Burgundy Red variety can be used to French fries processing due to their low content of TGA (in unpeeled and peeled potatoes). However, Blue Congo variety with blue-fleshed should not be applied to French fries processing, because of high TGA content in raw material and first of all in peeled potatoes flesh. The peeling process of coloured-fleshed potatoes decreased in TGA content on average by about 50 %, cutting process on average by about 53 %, whereas blanching on average by about 58 % compared with the raw material. The highest decrease in TGA content was caused by frying process. The mean values were about 97.5 % in ready-to-eat French fries. In French fries after I and II steps of frying, the ratio α-solanine to α-chaconine was lower (1.0:2.0) than in unpeeled potatoes (1.0:2.3).     

Impact of γ-irradiation,CIPC treatment,and storage conditions on physicochemical and nutritional properties of potato starches

In the present study, three potato varieties were treated with chlorpropham (CIPC, 35 ppm), γ-irradiated (0.1 kGy) and stored for up to 5 months at 8 °C, and the physicochemical properties and in vitro starch digestibility of native and cooked starches were investigated. Sprouting was found to be satisfactorily suppressed by γ-irradiation and CIPC treatment. However, irradiation increased total free glucose content in two potato varieties, and decreased the thermal transition and pasting temperature of starch. The crystallinity of starch in irradiated potatoes decreased significantly (p ? 0.05) which may explain its decreased resistant starch content. Sprout inhibiting treatments and storage had no effect on in vitro starch digestibility in cooked starches, but cooling cooked starch significantly (p ? 0.05) increased its resistant starch content.     

Potato Quality as Affected by Source of Magnesium Fertilizer: Nitrogen, Minerals, and Ascorbic Acid

TWO SOURCES of magnesium fertilizer, Epsom salt and dolomite, were compared as to their effect on nitrogen, mineral, and ascorbic acid contents of Katahdin potatoes. Both Mg sources increased significantly (p < 0.05) the total, nonprotein, and protein nitrogen of both cortex and pith tissues. The pith tissue was significantly (p < 0.05) higher than the cortex in total and nonprotein nitrogen. Potatoes fertilized with Epsom salt were higher in nitrogen than those receiving dolomite. Both sources of Mg significantly (p < 0.05) increased Al and Fe contents of tubers, and the greater increase occurred with Epsom salt. Tubers from soils receiving dolomite were significantly (p < 0.05) higher in manganese and cadmium contents than those receiving Epsom salt. No significant differences were observed in ascorbic acid content with either Mg source.     

Bisulfite Atlernatives in Processing Abrasion-Peeled Russet Burbank Potatoes

Whole, abrasion-pecled Russet Burbank potatoes were dipped in a solution containing 3% D-araboascorbic acid (erythorbic acid), 0.25% sodium acid pyrophosphate and 2% sodium chloride or water. They were drained and packed in 0.2% citric acid, 0.2% sorbic acid and 0.25% calcium chloride or water, sealed in plastic bags and stored at 3.8°C. Potatoes packed in the citric acid mixtures maintained a lower microbial load after 6 days storage when compared to bisulfite-treated or water-dipped potatoes. All potatoes maintained acceptable color through 18 days storage. Treatments did not alter shear force measurements of raw, peeled potatoes or perceived flavor and texture of cooked, mashed potatoes.     

Textural and pasting properties of potatoes (Solanum tuberosum L.) as affected by storage temperature

Fresh tubers from five potato (Solanum tuberosum L.) cultivars were stored at different temperatures (4, 8, 12, 16 and 20 °C) and 80–90% relative humidity for 18 weeks after harvest to examine the effect of storage temperature on their textural and pasting properties. Texture profile analysis was performed on raw and cooked potatoes using an Instron universal testing machine to measure textural parameters such as fracturability, hardness, cohesiveness, adhesiveness and springiness. Both raw and cooked potato tubers showed a considerable reduction in all textural parameters upon storage, irrespective of the storage temperature employed. Raw potatoes showed a decrease in fracturability and hardness with increasing storage temperature, whereas their cooked counterparts showed the opposite trend. The extent of change in the textural properties of both raw and cooked potatoes also varied among the different cultivars. Fresh and stored tubers from all cultivars were freeze‐dried, ground into flours and analysed for amylose content and pasting properties. The amylose content of flours prepared from potatoes stored at 4 and 8 °C was observed to be considerably lower than that of flours prepared from potatoes stored at 16 and 20 °C. Pasting characteristics such as peak viscosity, setback and final viscosity increased with increasing storage temperature, while the reverse was observed for pasting temperature, when studied using a rapid visco analyser. Breakdown in viscosity of the flour pastes from all cultivars was considerably reduced during storage, irrespective of the storage temperature employed. Copyright © 2006 Society of Chemical Industry     

Low-temperature Blanch Improves Textural Quality of French-fries

Potatoes, CV. Alpha, were sorted (specific gravity), peeled, cut, and blanched at four temperatures (55—70°C) for several times (0—60 min.) before frying in vegetable oil (200°C, 4 min). Multiple puncture (raw potatoes) and single puncture and Texture Profile Analysis (TPA) of French-fries were used. Limpness angle and oil retention (Carver press) were also evaluated. Firmness and some TPA parameters (chewiness, cohesiveness) were increased (>200%) by blanch. Limpness and oil content were reduced by treatment. Improvement of French-fries texture resulted after blanching for 30—45 min. at 60—65°C.     

Determination of Musty Odor Compounds Produced by Streptomyces griseus and Streptomyces odorifer

White potatoes and corn meal bread were treated with Streptomyces griseus and Streptomyces odorifer and stored 3 or 5 days at 30 ± 3°C with the objective of studying the growth of the two actinomycetes cultures and the distribution and nature of musty odor compounds that they may produce. Actinomycetes represented 11 - 14% of the total plate count after storage. Although judges rated treated samples as significantly (p < 0.05) more musty, gas chromatography and mass spectrometry analyses revealed that the actinomycetes cultures studied did not produce geosmin or 2- methyl-isoborneol, two important musty odor compounds.     

Production of a dry sausage from African catfish (Clarias gariepinus, Burchell, 1822): microbial, chemical and sensory evaluations

Production of a dry sausage from African catfish and determination of its microbial, chemical and sensory properties during a 70‐day storage at both 4 and 22 °C were prompted. pH of the samples at 4 and 22 °C did not significantly change during the storage (P > 0.05). Moisture content of the samples was 74%, and reduced to 45% at 4 °C and to 22% at 22 °C. Protein content of the samples was 20.71%, and increased to 42.5% at 4 °C and to 57.99% at 22 °C. Total lipid content was 4.5%, and increased to 10.98% at 4 °C and to 15.68% at 22 °C (P < 0.05). Microbial analyses showed that there was a significant reduction in total aerobic mesophilic and psychrotrophilic bacteria, total mould and yeast, total lactic acid bacteria, total Enterobacteriaceae and Staphylococcus aureus counts at both 4 and 22 °C (P < 0.05). Samples stored at 4 °C had significantly higher sensory ratings than that of the samples stored at 22 °C (P < 0.05).     

In vitro availability of starch in heat‐treated potatoes as related to genotype,weight and storage time

The objective of the study was to determine the influence of potato variety, weight and storage time after lifting on the glycaemic index (GI) and resistant starch (RS) content predicted from measurement of the rate and extent of in vitro starch hydrolysis, respectively. The potatoes were either boiled, or boiled and subjected to different heat‐cycling conditions selected to promote retrogradation of amylose or amylopectin, respectively. The hydrolysis indices (HI) and predicted GIs of all 19 potato products were high and fell within narrow ranges of 122–144 and 118–138, respectively. No correlation between average weight of the potato tuber and HI was found. Furthermore, there was no difference in HI between potatoes stored for 1–3 or 8–10 months, nor between varieties of new potato and winter potato. However, the HI was significantly lowered by temperature cycling at conditions known to promote retrogradation of amylopectin (6 °C, 48 h) compared with 6 °C for 24 h followed by 70 °C for 24 h. RS content was already substantial in boiled potatoes, 4.5 g 100 g^?1 (starch basis), and could be increased further by temperature cycling, the highest yield obtained, 9.8 g 100 g^?1 (starch basis), following heat treatment at 6 °C for 24 h followed by 70 °C for 24 h; that is at conditions known to favour amylose retrogradation. Copyright © 2004 Society of Chemical Industry     

Effect of Magnesium Fertilizers on Total Glycoalkaloids and Nitrate-N in Katahdin Tubers

The effect of two sources of magnesium fertilization (56 kg/ha, MgO). ensom salt and dolomite. on total alvcoalkaloid (TGA) and nitrate-nitrogen (N0₃-N) content of Katahdin potatoes was examined. Both magnesium fertilizers increased the TGA and NOJ-N content of tubers. Tubers grown in soils receiving epsom salt had significantly (p < 0.05) higher TGA content than the tubers receiving dolomite immediately following harvest, but after 5 mo storage, no significant differences were observed between the two Mg sources. The NO₃-N levels in tubers from plants receiving Mg fertilization were higher than the controls. Those receiving epsom salt were higher than those receiving dolomite. The N03-N levels decreased in all tubers after 5 mo storage. Cortex tissue was significantly (p < 0.05) higher in N03-N than the pith.