Ascorbic Acid Retention in Retort Pouched Green Beans

The L-ascorbic acid (AA) retention in and sensory quality of green beans processed under home-canning conditions in retort pouches and metal cans were compared. Green beans processed in cans retained slightly more AA than that processed in the pouches, possibly due to overprocessing of the pouched product. Metal cans offered better AA retention in the green beans than the retort pouches during 11 wk of storage at 21°C, due mainly to a higher rate of AA degradation occurring in the pouched product during the first week of storage. Sensory evaluation showed that the retort pouched beans were significantly better (p < 0.05) than the canned green beans in flavor, texture, and overall acceptance, but not in color.     

β-Carotene and Ascorbic Acid Retention in Fresh and Processed Vegetables

Broccoli, carrots, and green beans (grown in 2 consecutive years) were randomly divided into 3 treatments: fresh-refrigerated (F-R), frozen (FZ) or canned (C) (carrots only). FZ or C vegetables were processed within 24 h and stored for up to 1 yr. F-R vegetables were held at 4 °C for 3 wk (broccoli and green beans) or 6 mo (carrots). Trans b-carotene (Tb-C) and total ascorbic acid (AA) were determined at specified times, before and after microwave cooking. Vitamin content differed between years due to environmental conditions. Blanching resulted in AA loss, but retention remained stable after freezing broccoli and green beans. F-R green beans lost >90% AA after 16 d storage. Linear decreases in AAwere found in most F-R or FZ vegetables. Tb-C decreased slightly during freezer storage. Reductions in Tb-C occurred in canned carrots. Microwave cooking had minimal effects on AA or Tb-C.     

Oxidation-Reduction Potentials of Canned Foods and Their Ability to Support Clostridium Botulinum Toxigenesis

Oxidation-reduction potentials (Eh) of canned foods ranged from -18 to -438 mV. Foods packed in glass had higher redox potentials than those packed in cans. Only 4 out of 26 products tested reached positive redox values after exposure to air for 24 hr at 4°C. Inoculated containers of mushrooms, whole corn, cream corn, asparagus, beef gravy, kidney beans, green beans, cream of mushroom soup, cheddar cheese soup, and lima beans supported toxin production by C. botulinum; potatoes and beets did not.     

Low Temperature Blanching Effects on Chemistry, Firmness and Structure of Canned Green Beans and Carrots

Green beans and carrots were canned using extended blanching at 64–65°C and added calcium and/or acid. Firmer products resulted from all treatments but lowered pH was most effective. Blanched green beans were firmer with lower pectin esterification, indicating pectin methyl esterase activity. Green beans and carrots treated with calcium and/or acid and then cooked were firmer than controls. Acid exhibited a firming effect, perhaps by loosening tissue, while calcium reduced the influence of heat. Instrumental bioyield values correlated with sensory results of canned green beans; bioyield may result from a scleriformic layer. Microscopy showed firmer beans had intact middle lamellae while softer samples contained separated cells. These data suggest that the treatments rendered pectates in the middle lamella less heat labile.     

Processing Factors Influencing Splitting and Other Quality Characteristics of Canned Kidney Beans

Single factor changes from a standard canning process indicated that significant reductions in splitting resulted from higher soak Ca concentrations, higher soak temperatures, higher brine Ca concentrations, and shorter cooking times. Splitting in canned kidney beans was markedly reduced by soaking beans before cooking at temperatures of 66–71°C in solutions containing 150–350 ppm CaCl₂. Treatments giving lower gain in weight during soaking led to less splitting. Lower splitting was associated with lower drained weight and firmer cooked beans.     

Firming of Canned Vegetables by Addition of Lactose

Blanched carrots, green beans, and peas were retorted at 121°C in 2% NaCl brine containing variable amounts of dissolved lactose. After 37 and 68 days, hardness of the canned vegetables was tested by Instron. Increasing lactose content correlated significantly with average hardness of peas (r = 0.94 and 0.96, respectively), beans (r = 0.81 and 0.91), and to a lesser degree, carrots (r = 0.71 and 0.37). All products from brines containing 8% or more lactose showed higher average hardness than those containing less or no lactose. The increase in hardness was noticeable to an untrained sensory panel. Samples packed in 8–15% lactose brines were ranked significantly higher in firmness than those canned with 5% or less lactose.     

Nutritional and Sensory Properties of Canned and Stored Moin-Moin

Canned moin-moin was studied for nutritional and sensory properties after processing and following storage at 22.2°C and 29.4°C for periods up to 6 months. Comparisons were made with freshly prepared, traditional steamed moin-moin. The canned product remained a very good source of thiamin after thermal processing and storage losses. Chemical assays of lysine, available lysine, methionine, and tryptophan showed no losses of these amino acids from processing or storage, but PER values indicated that thermal processing significantly decreased protein quality of products in rat feeding studies. PER values of canned product then remained stable in storage. After 6 months at both storage temperatures, a Nigerian taste panel ranked overall acceptability of the canned product at 6.5 on a 9 point nedonic scale, compared to 7.5 for the freshly prepared traditiona moin-moin.     

Quality Comparison of Thermoprocessed Fishery Products in Cans and Retortable Pouches

The physical, chemical and sensory properties of rainbow trout, pollock and shrimp processed at equal lethalities in cans and retortable pouches were compared at certain storage periods. Pouched rainbow trout, pollock and shrimp required respectively 34%, 32% and 37% less thermal processing time than the canned product. The pouched products had lower amounts of ammonia, trimethylamine and total carbonyl compounds than the canned products. The pouched products retained 17%, 9% and 15% more Vitamin B₁ than the canned products for rainbow trout, pollock and shrimp, respectively. Pouched products had a firmer texture and lighter color than the canned products. In sensory evaluations, the pouched products were scored higher, in most cases, for color, flavor and overall acceptability.     

Storage Stability of Vegetables Fermented with pH Control

Vegetables fermented by Lactobacillus plantarum with pH control were microbiologically stable during 12-months' storage in hermetically sealed jars at ca. 24°C provided all fermentable sugars were removed during fermentation, and the products were stored at pH 3.8 or below. Fermented green beans, cucumbers, red and gieen bell peppers, and green tomatoes were thus rendered microbiologically stable. Fermented red beets and carrots, which contained residual sucrose, underwent secondary fermentation. Calculated carbon recoveries of the fermented vegetables ranged from 74–146%.     

Can Fitting in Green Beans: Effect of Growing Season, Base Steel Composition, Tinplate Thickness, Can Vacuum and Storage Conditions

Spring and fall grown green beans were packed under high and low vacuum conditions in high and low residual Al, Ni, Cu, Si, S, and Mn base steel .25 and .50 electrotin plated J-enamel cans and evaluated during storage at 38°C and room temperature for pitting on and under the s deseams. Cans containing spring grown beans were more severely pitted than those of the fall pack. High residual (0.061%) Cu steel cans were more severely pitted than other treatments. The .25 electrotin plated cans were more severely pitted in high Cu residual cans, as were the low vacuum spring pack cans at 38°C storage.     

Effects of Vacuum Hydration on the Incidence of Splits in Canned Kidney Beans (Phaseolus vulgaris)

Dry red kidney beans were canned using two different pretreatments: soaking for 12 hr at 20°C, and vacuum hydration for 5 min followed by soaking for 2 hr at temperatures from 45-59.1°C. Samples were then packed, processed to commercial sterility, and tested for percentage of split beans after processing. Vacuum hydration pretreatments greatly decreased the incidence and severity of splitting in the canned product and accelerated water uptake while retaining the same moisture content after soaking as the conventional soak treatment. Vacuum-hydrated beans gained less moisture during retorting than conventionally treated samples.     

Effects of Frozen Storage on Survival of Staphylococcus aureus and Enterotoxin Production in Precooked Tuna Meat

This study investigated the survival of Staphylococcus aureus in precooked tuna meat for producing canned products during frozen storage (?20 ± 2 °C) as well as its growth and enterotoxin production at 35 to 37 °C after the storage. Samples (50 ± 5 g) of precooked albacore (loin, chunk, and flake) and skipjack (chunk and flake) tuna were inoculated with 5 enterotoxin‐producing strains of S. aureus at a level of approximately 3.5 log CFU/g and individually packed in a vacuum bag after 3 h incubation at 35 to 37 °C. Vacuum‐packed samples were stored in a freezer (?20 ± 2 °C) for 4 wk. The frozen samples were then thawed in 37 °C circulating water for 2 h and incubated at 35 to 37 °C for 22 h. Populations of S. aureus in all precooked tuna samples decreased slightly (<0.7 log CFU/g) after 4 wk of storage at ?20 ± 2 °C, but increased rapidly once the samples were thawed and held at 35 to 37 °C. Total S. aureus counts in albacore and skipjack samples increased by greater than 3 log CFU/g after 6 and 8 h of exposure to 35 to 37 °C, respectively. All samples became spoiled after 10 h of exposure to 35 to 37 °C, while no enterotoxin was detected in any samples. However, enterotoxins were detected in albacore loin and other samples after 12 and 24 h of incubation at 35 to 37 °C, respectively. Frozen precooked tuna meat should be used for producing canned tuna within 6 to 8 h of thawing to avoid product spoilage and potential enterotoxin production by S. aureus in contaminated precooked tuna meat.     

Quality changes and storage life of common carp (Cyprinus carpio) at various storage temperatures

The shelf life and freshness changes in pond-grown common carp (Cyprinus carpio L) during storage at 0–2°C, 5–6°C and room temperature (26–29°C) were investigated by sensory, microbiological, physical and chemical analyses. The effect of gutting on the shelf life during storage at 0–2°C was examined. Iodine/starch and potassium sorbate were examined for their effects on shelf life of whole fish stored at 0–2°C and 5–6°C. Sensory results indicated that the whole fish had a maximum shelf life of 24 to 25 days at 0– 2°C. The life of the fish to the point beyond which it would be unsuitable for sale (commercial shelf life) was 17 days at 0–2°C. Storage at 5–6°C shortened shelf life 2- to 2.5-fold. At room temperature (26–29°C), spoilage was evident after 13 h. Gutting the carp shortened its storage potential at 0–2°C. Iodine treatment of this species stored at 0–2°C and at 5–6°C did not extend shelf life. The maximum shelf life of sorbate-treated fish at 0–2°C and 5–6°C was extended by 1–2 days, commercial shelf life by 3–4 days. Total volatile basic nitrogen, pH and penetrometer analyses were not reliable indicators of changes in freshness during shelf life. Thiobarbituric acid values were not useful as rancid odours or flavours were not detected during storage.     

Effect of chitosan and chitooligosaccharide on vitamin C and polyphenols contents in cherries and strawberries during refrigerated storage

The objective of this research was to investigate the effect of treatment with chitosan and chitooligosaccharide on vitamin C and polyphenols contents in cherries and strawberries during refrigerated storage. Chitosans and chitooligosaccharides, as well as vitamin C and polyphenols are associated with reduced risk of cardiovascular diseases and cancer. Synthesis of vitamin C in strawberries and loss of vitamin C in cherries were observed during refrigerated storage. The treatment with chitosan and chitooligosaccharides inhibits vitamin C synthesis in strawberries and promotes vitamin C synthesis in cherries. Lower values of anthocyanin content for strawberries and higher values of anthocyanin content for cherries treated with chitosan and chitooligosaccharide compared with anthocyanin content in control strawberries and cherries were found after 7 days storage at 4 °C. Total phenols content in strawberries decreased and in cherries increased after storage 7 days at 4 °C and more pronounced changes observed for samples treated with high molecular weight chitosan. The correlation between moisture content in treated and non-treated strawberries and contents of vitamin C, anthocyanin and total phenols was shown. No correlation between moisture content and content of vitamin C, anthocyanins and total phenols was found for cherries.     

Effect of cooking or handling conditions on the furan levels of processed foods

The aim of this study was to investigate the possible effects of cooking or handling conditions on the concentration of furan in processed foods. The analytical method used to analyse furan levels in foods was optimized based on solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). In baby soups, the concentration of furan decreased by up to 22% after opening a lid for 10 min. In the baby food in retort packaging, the level of furan was reduced by 15–33% after heating the foods at 50°C without a lid. Furan in rice seasonings was evaporated completely after heating the foods at 60°C. Regarding powered milk, the levels of furan were too low to be compared under various conditions. The levels of furan decreased to 58% in beverage products for babies, after storing them at 4°C for 1 day without a lid. The levels of furan in canned foods such as cereal and vegetable were reduced by zero to 52% when they were stored without stirring in a refrigerator at 4°C for 1 day. When we boiled canned fish, the furan present was almost completely evaporated. It is recommended that canned meats be heated up to 50–70°C for the reduction (26–46%) of furan levels. The levels of furan in instant and brewed coffee samples were significantly reduced after storing for 11 to 20 min at room temperature without a lid (p < 0.05).     

Canning Quality Evaluation of Pinto and Navy Beans

Thermal processing of pinto and navy beans at 121.1°C for 16 or 14 min in a still retort gave similar sterilization value (F_o= 10) as the processing at 115.6°C for 45 min. The 121.1°C/16 or 14 min process produced beans with greater firmness than the 115.6°C/45 min process. The addition of CaCl₂ and EDTA improved firmness and color of canned beans. Calcium chloride also reduced clumping and splitting of the canned beans. Sensory evaluation showed that the acceptability of canned beans was reduced when CaCl₂ was increased up to 10 mM. High correlation between firmness and soluble pectin in various bean cultivars implied that soluble pectin content could be used as a parameter for screening bean cultivars with desirable firmness.     

Effect of Fertilization, Postharvest Handling and Blanching Temperature on the Drained Weight of Canned Summer Squash

There was no apparent effect on drained weight or firmness when three rates of calcium fertilization and two rates of potassium fertilization were applied to a test planting from which two harvests of raw summer squash were canned. However, high Ca (L₂) decreased dry matter and increased structural carbohydrates and tissue Ca in the canned product. Precooling increased drained weight and dry matter, but drastically reduced firmness of the canned product. Noncooled canned squash had lower drained weights and pH, but greater firmness and higher water soluble pectin and cellulose content. Blanching at 99°C increased drained weight; blanching at 88°C decreased drained weight, but increased calgonsoluble pectin content.     

Quality Attributes of Fermented and Acidified Green Beans

A study was conducted with two styles and four blanch methods on green beans which were acidified with one of four organic acids or fermented. The beans were compared with conventional canned beans for selected quality attributes. Analyses showed that acidified and fermented beans were acceptable in color, firmness and flavor regardless of style, blanch or storage. The acidified and fermented beans were much firmer with less sloughing than conventional canned beans. Minor differences were noted in nutritive value of the beans. Panel ratings for flavor of acidified beans were not significantly different from the conventional canned beans except in fermented beans. Flavor differences in fermented beans were probably caused by flavor volatiles produced by the bacteria. Acidified and fermented beans should be suitable for many types of dishes prepared with green beans such as casseroles, salads, etc. as well as for salad bars.     

Quality of Green Beans, Bell Peppers and Spinach Stored in Polyethylene Bags

Quality attributes of packaged and unpackaged vegetables generally decreased nonlinearly during storage at 10°C or 20°C, and most of the decrease was greater at 20°C than at 10°C. Packaging reduced weight loss of green beans and spinach kept at 20°C; and reduced chlorophyll loss of green beans at 10°C and of spinach at 20°C. Ascorbic acid (vitamin C) benefited by packaging of green beans and spinach kept at 10°C. Packaging had an effect on thiamin (vitamin B₁) of only spinach held at 10°C and 20°C and had no effect on riboflavin (vitamin B₂). Loss of these quality attributes appears to be enhanced with water loss.     

Effect of Heat Processing on Hemagglutinin Activity in Red Kidney Beans

The effect of temperature in destroying the hemagglutinin (lectin) activity in red kidney beans has been determined. Heating presoaked beans at 100°C for 15 min or at 80°C for 2 hr, or pressure cooking (15 psi) foi 45 min without presoaking, decreased the hemagglutinin activity to below detectable levels. At 65°C, no significant decrease was observed even after 12 hr heat treatment. Commercially canned beans have lectin levels similar to beans pressure cooked for 30 min.