Irradiation and Packaging Affect the Nitrate-Nitrogen Concentrations of Potatoes

Russet Burbank and Kennebec potato cultivars were irradiated with dosages of 0.1 and 1.0 KGy and stored in polyethylene or paper bags for 1 or 3 mo at 5°C or 20°C. Tubers receiving irradiation showed a significant (p<0.01) increase in nitrate-nitrogen concentration as compared to controls. Those receiving the 1.0 KGy dose had the highest nitrate-nitrogen concentration. Tubers stored in polyethylene bags were significantly (p<0.01) higher in nitrate-nitrogen concentration than those stored in paper bags. Tubers stored at 20°C were significantly (p<0.01) higher in nitrate-nitrogen than those stored at 5°C. These trends were consistent for both cultivars. The cortex region was significantly (p<0.01) higher in nitrate-nitrogen concentration than the pith region. Kennebec tubers were significantly (p<0.01) higher in nitrate-nitrogen than the Russet Burbank tubers for all irradiation doses and storage temperatures.     

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.     

Effects of controlled atmosphere storage and low-dose irradiation on potato tuber components affecting acrylamide and color formations upon frying

The effects of normal and controlled atmosphere combinations on tuber components responsible for acrylamide formation were studied during prolonged storage at 9±1 °C using the tubers of “Agria” and “Russet Burbank.” The effects of low-dose irradiation (50, 200 Gy) prior to normal atmosphere storage were also studied. There was only a limited increase in the concentrations of sugars during 6 month of storage under normal atmosphere conditions. Low-dose irradiation slightly decreased the rate of sweetening in the tubers. The potential of acrylamide formation remained almost the same; however, the loss of firmness became clearer during 6 month of storage under normal atmosphere conditions. Controlled atmosphere storage in which O₂ was deficient to a sufficient respiration increased the concentrations of sugars, and thus, the potential of acrylamide formation in potatoes upon frying at 170 °C for 10 min. The sum of glucose and fructose concentrations showed a good correlation (r ²∼0.90) with the potential of acrylamide formation for both cultivars.     

Influence of heating conditions and starch on the storage modulus of Russet Burbank and Yukon Gold potatoes

The storage modulus of Russet Burbank (RB) and Yukon Gold (YG) potato discs (13.3 mm × 4.5 mm) was measured continuously during heating in water at temperatures ranging from 40 to 80 °C for 120 min using a dynamic mechanical analyser with a heating stage. The starch content of YG potatoes was higher than that of RB potatoes, but the raw starch granule size distribution of both varieties was similar. RB samples had the highest storage modulus values (25% higher than raw tissue) when heated in 60 °C water for 35 min. Image analysis revealed that the perimeters of starch granules in the potato samples increased by about 50% during heating for 30 min at 60 °C. Heating temperature and time and starch content influenced the storage modulus. © 2001 Society of Chemical Industry     

Effect of Sprout Inhibitor Isopropyl-N(3=Chlorophenyl)-Carbamate on Total Glycoalkaloid Content of Potatoes

The effect of the sprout inhibitor, isopropyl-N-(3-chlorophenyl)-carbamate (CIPC) on total glycoalkaloid (TGA) content of potatoes was investigated. Katahdin and Chipbelle potatoes grown at Cornell Research Farms, Freeville, NY and Riverhead, NY, were used. Potatoes treated with CIPC were significantly (p < 0.05) lower in TGA content than the controls. Potatoes stored at 25°C were significantly (p < 0.05) higher in TGA content than those stored at 5°C and TGA content increased significantly (p < 0.05) with increasing storage time.     

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.     

Gamma-Irradiation of Frozen Kiwifruit Pulp

Frozen (–18°C) de-seeded kiwifruit pulp (Actinidia deliciosa) was irradiated at a dose of 100 krad and stored at -18°C. Irradiation resulted in a 2.11 log₁₀ reduction in aerobic plate count (APC) with bacteria being most susceptible. Molds were less susceptible than yeasts. Assessments carried out over 6 months storage showed no significant differences in physical, chemical and sensory properties between irradiated and nonirradiated pulps. The microbial populations of the pulps decreased in parallel throughout the storage period. Frozen storage without irradiation resulted in a 3 log₁₀ reduction in APC over the 6 months period, a 38% reduction in ascorbic acid, and a slight loss of color. Three days frozen storage (– 18°C) following irradiation resulted in an APC only 0.89 log₁₀ higher than 6 months frozen storage (- 18°C) without irradiation with potential savings in energy and holding times which could have economic benefits.     

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.     

Application of electron‐beam irradiation pasteurization of ground beef,from steers fed vitamin E fortified diets: microbial and chemical effects

The effects of vitamin E supplementation of diets and electron‐beam irradiation (EBI) processing of ground beef patties on microbial and chemical qualities were investigated during 21 days of storage at 4 °C. Oxidative damage to lipids induced by EBI in ground beef patties containing different fat contents was first determined at 3 day intervals throughout a 7 day storage period at 4 °C. Significantly (P ≤ 0.05) higher values for thiobarbituric acid reactive substances (TBARS) were detected in beef patties of higher fat content (ie at 17 and 30%), which was further enhanced by irradiation at 5 kGy. Since lipid oxidation proceeded to a greater extent in beef patties with higher fat levels, ground beef patties of 30% fat were prepared from steers fed basal (diet I) or basal + 500 IU (diet II) of the antioxidant (vitamin E) supplemented diets. Plasma vitamin E concentrations in cattle fed diets I and II were 1.58 ± 0.42 µg ml^?1 and 2.49 ± 0.40 µg ml^?1 respectively. Patties were processed with three doses (2, 5, or 10 kGy) of EBI and compared with non‐irradiated patties. Microbial indices monitored at 3 day intervals included total aerobic plate count, psychrotrophic counts, and total coliform and Escherichia coli counts. Bacterial growth in ground beef patties stored at 4 °C was significantly (P ≤ 0.05) reduced by EBI at 2 kGy dose. Complete inhibition of bacteria occurred at 5 kGy or higher (P ≤ 0.05) dosage of EBI over 21 days of storage at 4 °C. Quality indices monitored at 3 day intervals throughout a 21 day storage (4 °C) study involving 30% fat ground beef patties made from steers fed vitamin E supplemented diets I and II included TBARS and colour. Results indicated that irradiation at the highest dosages was associated with higher (P ≤ 0.05) TBARS values, which in turn corresponded to lower linoleic acid content. With all three levels of irradiation, Hunter a values of beef patties decreased (P ≤ 0.05) significantly. Lipid oxidation was significantly (P ≤ 0.05) retarded in stored beef patties derived from cattle fed vitamin E (diet II). Copyright © 2003 Society of Chemical Industry     

Effect of Low Temperature Storage on Sugar Concentrations and Chip Color of Certain Processing Potato Cultivars and Selections

Two potato cultivars (Kennebec and Simcoe) and one selection (ND 860–2) were stored for 3 months at 4°, 9° and 11°C. ND 860–2 had the lowest sugar content at all storage temperatures, produced the lightest colored chips and was the only sample which gave acceptable colored chips directly from 4°C storage. In another study, three potato cultivars (Norchip, Simcoe and Onaway) and one selection (ND 860–2) were evaluated for sugar content and chip color during growth and harvest, two weeks prior and two weeks after foliar senescence, and stored under various time —- temperature regimes and upon reconditioning. ND 860–2 generally had the lowest levels of fructose, glucose and sucrose and Onaway had the highest. Storage at 5°C resulted in increases in the three sugars for all tubers, sucrose showing the most notable increase. ND 860–2 was the only sample to consistently produce acceptable colored chips directly from 5°C.     

Effect of harvest time and storage conditions on almond kernel oil and sugar composition

The effect of storage for 6 months at 5 °C (80% RH) versus 20 °C (60% RH) of shelled versus in‐shell almonds was studied on early versus late harvested nuts from ‘Ferragnes’ and ‘Texas’ trees. Kernel quality characteristics, oil composition and sugar composition were determined initially and after 6 months of storage. Early harvested almonds had similar kernel weight to but higher moisture content than late harvested almonds after 6 months of storage. Early harvested almonds also had similar oil quality (based on ultraviolet absorption coefficient measurements) and oil composition but lower sugar content and modified sugar composition compared with late harvested almonds. Storage of shelled almonds resulted in kernels with higher oil content, better oil quality, similar oil composition, similar sugar content and some modifications in sugar composition compared with in‐shell stored almonds. Finally, storage for 6 months at either 5 or 20 °C resulted in lower moisture content, higher oil content, similar oil quality and composition, similar sugar content and some modifications in sugar composition compared with freshly harvested almonds. Almonds stored at 5 °C retained higher kernel weight and moisture content than almonds stored at 20 °C. © 2003 Society of Chemical Industry     

Effect of freezing/thawing conditions and long‐term frozen storage on the quality of mashed potatoes

The effects of freezing temperature (−80, −40 or −24 °C) and thawing mode (microwave or overnight at 4 °C) on quality parameters of mashed potatoes made from tubers (cv Kennebec) and from potato flakes were examined, as was the effect of long‐term frozen storage on the quality of mashed potatoes. Mashed potatoes were tested for texture profile analysis (TPA) and cone penetration, oscillatory and steady rheometry, colour, dry matter, Brix and sensory analyses. In natural mashed potatoes, TPA hardness and oscillatory parameters showed that processing resulted in a softer product than the fresh control. The parameters were lower in the samples thawed at 4 °C than in those thawed by microwave at all the freezing temperatures used, which may be ascribed to gelatinisation of the starch released from damaged cells. Differences from the freshly prepared product decreased when the samples were frozen at −80 °C and thawed by microwave. No difference was found in sensory acceptability between samples frozen at −80 and −40 °C, which probably reflects the panellists' mixed preferences for air‐thawed versus microwave‐thawed samples. Increasing the time in frozen storage led to a natural mash with a firmer texture, higher L*/b* value and Brix; nonetheless, panellists found the samples at 0, 3 and 12 months of frozen storage equally acceptable. In commercial mash, penetration and oscillatory parameters showed that processing made for a firmer product than the fresh control, probably owing to retrogradation of gelatinised starch. Thawing mode had a significant effect on parameters, which were lower in the samples thawed at 4 °C. The structure and quality of commercial mash was more detrimentally affected by freezing and, therefore, we would not recommend either freezing or frozen storage of this mashed potato in the used conditions. Natural mash made from Kennebec potatoes should be frozen quickly and thawed by microwave in the conditions described to obtain a product more similar to that freshly made. If the samples are frozen by air blasting at −40 °C, the product can withstand frozen storage for one year. Copyright © 2005 Society of Chemical Industry     

Effect of lipid oxidation and frozen storage on muscle proteins of Atlantic mackerel (Scomber scombrus)

The effect of storage on the lipids and proteins in Atlantic mackerel stored for up to 24 months at ?20 and ?30 °C was studied. Traditional methods including the peroxide value, thiobarbituric acid‐reactive substances (TBARS) and a reverse phase HPLC method were used to determine the primary and secondary lipid oxidation products. All tests showed an increase in lipid oxidation products with storage time and at a higher storage temperature of ?20 °C compared with samples stored at ?30 °C. Antioxidants had a significant effect (P < 0.01) on the inhibition of lipid oxidation, as shown by the reduction in peroxide value and hydroxides, and malondialdehyde formation. Similarly, deterioration of protein structure and functionality in mackerel stored for 3, 6, 12 and 24 months was greater at ?20 than ?30 °C. ATPase activity in the myosin extract of Atlantic mackerel showed a significant decrease (P < 0.01) with progressive frozen storage. Protein solubility in high salt concentration (0.6 M NaCl) decreased (P < 0.01) during storage at both ?20 and ?30 °C but was greater at ?20 °C. Interestingly, antioxidants BHT, vitamin C and vitamin E protected the proteins against complete loss of ATPase activity and protein solubility to a significant level (P < 0.01) for up to 1 year at ?20 °C compared with samples stored without antioxidants. This study confirms the deleterious effect of lipid oxidation products on protein structure and function in frozen fatty fish. © 2002 Society of Chemical Industry     

The effect of storage temperature and time on the consistency and color of sterilized processed cheese

The effect of sterilization (117 °C for 20 min) on the color and consistency of processed cheeses was evaluated. The sterilization resulted in a darker shade (darker color) and increased firmness and elasticity of processed cheeses (P < 0.05). During the storage period (24 months) of sterilized processed cheeses, their color as well as consistency changed depending on the temperature tested (8 and 23 °C). The color change of sterilized processed cheeses was more significant at a higher storage temperature (23 °C) in comparison with the products kept at cold storage temperature (8 °C) (P < 0.05). The firmness of sterilized processed cheeses stored at 8 °C increased during the 24 months. The rise in firmness achieved in the products stored at 23 °C was followed by its decrease in the second year of storage.     

Comparison of sodium acid sulfate to citric acid to inhibit browning of fresh-cut potatoes

Abstract: Sodium acid sulfate (SAS) dip treatments were evaluated against a distilled water control and citric acid (CA) to compare its effectiveness in reducing enzymatic browning of raw, French‐fry cut potatoes. Two separate studies were conducted with dip concentrations ranging from 0%, 1%, and 3% in experiment 1 to 0%, 2%, and 2.5% in experiment 2 to determine optimal dip concentrations. Russet Burbank potatoes were peeled, sliced, and dipped for 1 min and stored at 3 °C. Color, texture, fry surface pH, and microbiological analyses were conducted on days 0, 7, and 14. The 3% SAS‐ and CA‐treated samples had significantly (p < 0.0001) lower pH levels on fry surfaces than all other treatments. Both acidulants had significantly (p ≤ 0.05) lower aerobic plate counts compared to controls in both studies by day 7. However, SAS appeared to be the most effective at the 3% level in maintaining a light fry color up to day 14 and had the highest L‐values than all other treatments. The 3% SAS‐treated fry slices appeared to have the least change in textural properties over storage time, having a significantly (p = 0.0002) higher force value (kg force [kgf]) than the other treatments during experiment 1, without any signs of case‐hardening that appeared in the control and CA‐treated samples. SAS was just as comparable to CA in reducing surface fry pH and also lowering microbial counts over storage time. According to the results, SAS may be another viable acidulant to be utilized in the fresh‐cut fruit and vegetable industry.     

Effect of gamma irradiation on aflatoxin production in barley

Barley was inoculated with conidia of Aspergillus parasiticus NRRL 2999, and at 0°C was left to equilibrate at three moisture levels: 17, 20 and 25%. Gamma irradiation at five doses, 0, 50, 100, 200 and 400 krad, was applied to the grain either soon after moisture equilibration (3 days after inoculation) or 10 days later (13 days after inoculation). Increasing the radiation dose resulted in decreasing aflatoxin formation, with one exception: 200 krad applied 13 days after inoculation on barley stored at a moisture level of 25% (100% relative humidity) and 25°C led to higher aflatoxin production than at 100 or 50 krad. For the control of aflatoxin contamination in barley, storage at low moisture content appears to be more practical and effective than irradiation.     

Influence of Injection, Packaging, and Storage Conditions on the Quality of Beef and Bison Steaks

The combined effects of injection, packaging (modified atmosphere packaging [MAP] with 70% O₂/ 30% CO₂ and vacuum packaging [VP]), storage temperature (‐1 °C and +4 °C), and storage time on the color, microbial and oxidative stability of beef and bison longissimus lumborum (LL) steaks were investigated. Beef LL steaks in MAP retained their bright red color longer than bison steaks. Bison steaks developed higher 2‐Thiobarbituric acid reactive substances (TBARS) during storage, and this might have influenced the resulting rapid loss of redness from the bloomed meat. Storage at ‐1 °C in MAP provided greater color stability and a longer storage life for both meat species studied. Injection of salt/phosphate had a beneficial effect on the color stability of steaks during retail display; however, this positive effect was more pronounced for bison steaks compared with those of beef. Steaks stored overnight under MAP before retail display maintained the highest a* values for up to 5 d compared with those stored under vacuum. MAP‐OV steaks generally maintained the highest OMB content for up to 5 d during retail display compared with those stored under vacuum. Nevertheless, OMB levels were significantly (P < 0.05) lower in bison steaks compared with those of beef irrespective of packaging treatments. Injected steaks and those stored at ‐1 °C had significantly (P < 0.05) higher OMB levels compared with non‐injected counterparts and those stored at +4 °C, respectively. MAP is an excellent option for short‐term storage due to its positive effects on meat color, but for longer storage, VP may be necessary. Storing meat under vacuum and then placing it under MAP just before retail display might be another option to increase shelf life.     

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.     

Changes in antioxidants and taste-related compounds content during cold storage of fresh-cut red sweet peppers

Changes in antioxidants (ascorbic acid, phenolic compounds and carotenoids) and in taste-related compounds (sugars and organic acids) content were monitored in fresh-cut red sweet peppers (Capsicum annuum L., local ecotype “Peperone Cornetto di Pontecorvo”) during 9 days of cold storage. Pepper slices were placed in polystyrene trays, wrapped with a polyvinyl chloride film, and stored at 4 °C or at 8 °C; besides, to evaluate the effect of a prestorage hot water treatment, half of the slices were subjected to a dipping treatment in water at 53 °C for 4 min, before packaging and storage. During storage limited changes in O₂ and CO₂ concentrations were observed within all packages. Storage temperature strongly affected weight loss: at the end of the storage time it was <3 and >10% in fruits stored at 4 and 8 °C, respectively. Sugars (glucose and fructose) content showed a significant increase (+11%) only in fruits stored at 8 °C; this change was due to a concentration effect associated to water loss. A higher increase (+23 and +17% in fruits stored at 8 and 4 °C) was observed in organic acids (citric and malic) content. Minimal processing and storage produced only a quite limited degradation of ascorbic acid. Both hydroxycinnamic acid derivatives and flavonoids accumulated in fruits stored at 8 °C (and not heat treated), whereas at 4 °C phenolics accumulation appeared to be partially inhibited. All the main carotenoids (capsanthin, cucurbitaxanthin A, zeaxanthin, β-carotene and β-cryptoxanthin) markedly accumulated in fruits stored at 8 °C (not heat treated), and showed a general decrease at 4 °C. Hot water treatment did seem to affect organic acids metabolism, though it did not promote ascorbic acid degradation. In addition, it inhibited both phenolics and carotenoid accumulation in fruits stored at 8 °C.     

The influence of storage temperature and storage time on color stability,retail properties and case-life of retail-ready beef

Steaks from three different muscles were either vacuum or carbon dioxide packed and stored for up to 24 weeks at three different storage temperatures (−1.5, 2, or 5 °C). Following storage, they were displayed for up to 30 h. CIE color coordinates, the oxidative states of myoglobin and pH were measured and muscle color, surface discoloration, retail appearance, and odor were evaluated prior to storage and during display (0, 1, 2, 4, 6, 24 and 30 h), and/or immediately prior to and following display. Prior to display, pH was negatively related to duration of storage, and samples stored at −1.5 °C had the highest and samples stored at 5 °C, had the lowest pH. Perception of muscle color was influenced by duration of storage and display, but lower storage temperatures appeared to produce a stabilizing effect. Both lightness of muscle color and deoxymyoglobin content were apparently not influenced by storage temperature or duration of storage or display. Both oxymyoglobin (OMB) and redness, as defined by CIE a* values, were lost progressively during storage and display, but this loss was progressively lower as storage temperature decreased. Yellowness of muscle color, as defined by CIE b* values, generally decreased as storage was prolonged, and this decrease was observed more quickly at higher storage temperatures. Surprisingly, b* values were not related to duration of display. Both surface discoloration and metmyoglobin (MMB) content increased progressively during storage and display. Samples stored at 5 °C displayed the most surface discoloration, while samples stored at −1.5 °C contained the least MMB and displayed the least surface discoloration. Retail appearance deteriorated progressively during storage in all samples stored at 2 and 5 °C and in samples stored at −1.5 °C, which were displayed for at least 24 h. Retail appearance also deteriorated progressively during display in samples stored at −1.5 and 2 °C for three weeks or longer and in samples stored at 5 °C for 0 to 15 and 24 weeks. In unstored samples, samples to be stored at −1.5 °C generally received the lowest retail appearance scores, but after prolonged storage and display, samples stored at −1.5 °C received higher retail appearance scores than samples stored at 5 °C, particularly when samples were stored for 12 weeks or longer and displayed for 1 h or more. Odor deteriorated progressively during storage when measured both prior to display and after 30 h of display. In samples stored for three weeks or longer, samples stored at −1.5 °C generally received the lowest odor scores and were perceived to have the least prevalent off-odors. Samples stored at −1.5 °C maintained a retail case-life of 30 h, when stored for up to 17 weeks, while samples stored at 2 and 5 °C maintained a retail case-life of 30 h, when stored for only eight and seven weeks, respectively. Consequently, storage life can be more than doubled by storage at subzero temperatures (−1.5 °C).