Effect of Harvest Date, Irrigation, Maturity and Calcium Addition During Processing on Quality of Canned Summer Squash

Soaking summer squash in calcium prior to commercial blanching at 99°C decreased sloughing, increased sensory firmness and had no effect on lightness or pH of the canned product. Although blanching squash in calcium decreased sloughing, improved lightness, decreased pH and produced off-flavors, the effect of hand blanching at 93°C with no calcium present increased sloughing, lightness, pH, and sensory firmness of the processed product. Adding calcium at the point of squash filling into cans after a commercial blanch produced no change in sloughing, decreased pH, increased sensory firmness and had no effect on lightness. Grade 1 squash exhibited the highest drained weight and lowest sloughing values. Drained weight increased at the end of the harvest season. Method of cultivation had no effect on the quality of canned squash.     

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.     

Changes in Chlorophyll and Pectin After Storage and Canning of Kiwifruit

Kiwifruit were harvested and stored at 0°C. Over a 92-day period fruit were removed from storage, ripened to 13° Brix by holding at 25°C, and canned as slices in a sugar syrup. Changes in the chlorophylls and pectic substances were measured after storage and canning. The concentration of total chlorophyll remained virtually constant during storage and ripening. During the canning process about 90% of the chlorophylls was degraded, the data fitting a first-order model better than a second-order model. The total pectin content increased by over 100% during storage and ripening but decreased significantly during canning. A significant inverse relationship between the firmness of unpeeled kiwifruit and the water-soluble, high-methoxyl pectin content was derived.     

RELATIONSHIP OF TREATMENT OF FRESH STRAWBERRIES TO THE QUALITY OF FROZEN FRUIT AND PRESERVES1

‘Cardinal’ strawberries were hand picked and stored 1 day at 21°C to enhance softening. Three separate preprocessing experiments were conducted to determine the effects of style of pack, 0.18% calcium (Ca) dips, 0.3% low methoxyl pectin (LMP), 40° Brix sucrose dips, heat of 70°C, vacuum at 172 mm Hg and drying to 70% moisture on quality and firmness of frozen-then-thawed and preserved strawberries. The greatest firming effect on frozen-then-thawed fruit was due to Ca and pectin. Sliced fruit was firmed more than whole fruit by the Ca and pectin treatments. Drained weight loss was reduced by pectin, Ca, sucrose, heat and vacuum in frozen-then-thawed fruit. Drained weight losses were the same or greater among treatments in preserves. The firmness and wholeness of preserves was increased by Ca, vacuum, 40° Brix sucrose, heat and to a lesser extent drying, but individual effects were not additive. The drying treatment reduced color quality.     

Strawberry Texture and Pectin Content as Affected by Electron Beam Irradiation

Fresh Tristar' strawberries were irradiated with electron beam irradiation at 0, 1, and 2 kGy. Fruit firmness decreased as irradiation dose increased. Water-soluble pectin increased and oxalate-soluble pectin decreased at 0 and 1 day after 1 and 2 kGy irradiation. Fruit firmness correlated with oxalate-soluble pectin content. Total pectin and nonextractable pectin were not affected by irradiation. The oxalate-soluble pectin content and firmness of irradiated strawberries increased slightly at the beginning of 2°C storage and then decreased as storage time increased. No changes occurred in water-soluble pectin, nonextractable pectin, or total pectin during storage.     

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.     

Dry Pea (Pisum Sativum L.) Canning Quality as Influenced by Soak Time, Soak Solution, and Cultivar

Hydration ratio of dry peas increased as soak time increased. Drained weights for the cv. Alaska decreased as soak time was increased, but drained weight for the cv. Garfield remained constant. Shear values increased for‘Alaska’, but decreased for‘Garfield’as soak time was extended. Moisture content decreased for‘Alaska’, but increased for‘Garfield’as soak time was extended. Objective color remained constant regardless of soak time. Sensory integrity (wholeness) was improved as soak time was extended for‘Alaska’peas. The addition of 0.5% CaCl₂ solution to canned peas reduced hydration ratios, drained weights, and color, and increased shear values and sensory integrity and appearance.     

Effect of Vacuum Impregnation Combined with Calcium Lactate on the Firmness and Polysaccharide Morphology of Kyoho Grapes (<Emphasis Type="Italic">Vitis vinifera</Emphasis> x <Emphasis Type="Italic">V. labrusca</Emphasis>)

The effects of vacuum impregnation (VI) with 2% calcium lactate treatment on the VI properties (obtained from hydrodynamic mechanism and deformation–relaxation phenomena models), firmness, and pectin of Kyoho grapes were investigated. Fruit pectin was analysed by atomic force microscopy (AFM). VI was applied for 10–35 min at 25–45 °C and 5 kPa. The maximum values of effective porosity, ε_e (0.606%), and volume fraction, X (0.588%), occurred at 35 °C when the VI time was 15 min. No change was observed in the volumetric deformation (γ ≈ 0) of the grapes after the impregnation. The firmness significantly increased at 35 °C VI (from 12.93 to 14.47 N). According to the AFM results, calcium mainly inhibited the degradation of chelate-soluble pectin and sodium carbonate-soluble pectin short branches during the VI. Under the studied conditions, the validity of VI to incorporate calcium into fruit to improve the quality of grapes was verified, and a final corresponding product was obtained by VI.     

CARBOHYDRATE TRANSFORMATIONS, COLOR AND FIRMNESS OF CANNED SWEET POTATOES AS INFLUENCED BY VARIETY, STORAGE, pH and TREATMENT

SUMMARY– Two varieties of sweet potatoes were canned at three storage intervals, six buffered pH levels, and two holding times to determine the influence on color, firmness, carbohydrates and other constituents. Color and firmness were improved when the pH was decreased from 8 to 3. There was an increase in brightness of color and firmness by holding peeled sweet potatoes 24 hr in buffers before canning. The sugars and phenolic substances were leached out during holding. Total polyphenols decreased with an increase in pH although tannic and chlorogenic acids were not changed appreciably. There was a decrease in starch and hemicellulose as a result of storage; whereas, water- and Calgon-soluble pectin were not affected. Starch decreased with an increase in pH regardless of other variables. Water-soluble pectin increased when pH was altered up or down from the normal pH of canned sweet potatoes of approximately 6.0. In comparison, Calgon-soluble pectin and hemicellulose reacted inversely to pH. It appeared that pH had a far greater effect on color and firmness than length of post-harvest storage of raw product after curing and other variables because of the direct effect on carbohydrate transformations and discoloration.     

A modified laboratory canning protocol for quality evaluation of dry bean (Phaseolus vulgaris L)

The effects of calcium (Ca²⁺) level in the soak water, blanch water and brine, blanching temperature, and total seed solids on dry bean canning quality were investigated to optimise a laboratory canning protocol. A linear increase in the Ca²⁺ level of soak water, blanch water and brine resulted in a linear decrease in hydration coefficient and percent washed drained weight but a linear increase in texture. Low Ca²⁺ level (10 mg kg⁻¹) reduced the hydration time for dry bean seed from 14 to 1 h. Blanching temperatures of 50, 70 and 88 °C had non‐significant effects on canning quality traits. Blanching for 30 min at 70 °C for black bean or at 88 °C for navy bean and pinto bean resulted in percent washed drained weight ≥ 60, as required by the Canada Agricultural Products Standards Act. Seed solids levels of 95–97 g per 300 × 407 (14 fl oz) can were sufficient to attain a percent washed drained weight of 60. It was confirmed that the thermal processing conditions (115.6 °C retort temperature, 45 min) used in this study were sufficient to achieve commercial sterility. The optimised lab protocol for evaluation of the canning quality of dry bean breeding lines is as follows. Seed containing 95 g of solids for pinto bean, 96 g for navy bean and 97 g for black bean is soaked in water for 30 min at 20 °C and blanched for 30 min at 70 °C for black bean and 88 °C for navy bean and pinto bean in water containing 10 mg kg⁻¹ of Ca²⁺. The seed is then transferred to a 300 × 407 can, filled with brine containing 10 mg kg⁻¹ of Ca²⁺, 1.3% (w/v) of NaCl and 1.6% (w/v) of sugar. The can is then sealed, processed in steam at 115.6 °C for 45 min and cooled at 20 °C for 20 min. Cans are stored for at least 2 weeks prior to quality evaluation of the canned product. Canning of dry bean seed according to this protocol results in precise estimation of canning quality traits, particularly percent washed drained weight. © 2000 Society of Chemical Industry     

Chemical and Physical Changes in Beet (Beta vulgaris L.) Root Tissue During Simulated Processing–Relevance to the "Black Ring" Defect in Canned Beets

Preheating slices of beet root tissue at 40 to 60°C led to a loss in tissue integrity indicated by higher leakage of electrolytes and endogenous pigments, and increases in water soluble pectin content. When tissue slices were incubated at 25°C for 1 hr after preheating at 50 to 60°C, reducing sugar increased. Incubation after preheating at 40 to 60°C resulted in decreased phenolic acid content. Endogenous poly-phenoloxidase and peroxidase retained about 50% of their original activity after preheating for 5 min at 70 and 60°C, respectively. These results bear relevance on the occurrence of the “black ring” defect in canned beets.     

The effect of processing on the texture of canned mung bean (Phaseolus aureus) shoots

The effect of various processing regimes on the pectic substances and the final texture of canned mung bean shoots has been studied. A blanching temperature of 75°C for 30 s was optimal in activating the native pectinesterase of the shoots and a holding temperature of 55°C for an optimal 30 min led to maximal deesterification of pectin. This treatment resulted in a canned product that was superior to a sample blanched at 100°C.; the addition of calcium ions did not improve the product.     

Thermal and Calcium Pretreatment Affects Texture, Pectinesterase and Pectic Substances of Frozen Sweet Cherries

Freezing causes loss of turgidity and firmness in sweet cherries. Thermal pretreatment at 50°C for 10 min followed by immersion in 100 mM CaCl₂ and thermal pretreatment at 70°C/2 min with or without immersion in 100 mM CaCl₂ prevented freezing-induced loss of firmness. Thermal pretreatments increased the pectin fraction soluble in EDTA, reduced the degree of pectin esterification, and increased both the concentration of divalent cations in the cell wall and the pectinesterase activity bounded to the cell wall. Immersion in CaCl₂ increased the concentration of Ca²⁺ cations in the cell wall and enhanced the effect of thermal pretreatments on pectinesterase activity.     

Effect of Blanch Temperature on Kinetics of Thermal Softening of Carrots and Green Beans

Cut green beans and diced carrots were blanched at 100°C and 74°C then canned and processed for 5 min to 300 min at 100°C. In every case the rate of thermal softening was consistent with the two substrate first-order kinetic theory of thermal softening of vegetable tissue. The low temperature blanch caused some changes in the apparent firstorder rate constants for both substrates, but the major difference was a much higher intercept of the extrapolated substrate S_S line on the firmness axis. We define S_S at zero process time as the “thermal firmness value” because it is a good indicator of what the firmness of the vegetable will be after canning.     

Changes in Pectic Substances and Enzymes during Ripening and Storage of "Keitt" Mangos

The relationship of the distribution of pectic substances to tissue softening was examined in ripening mangos at four stages of ripeness. Water-soluble and alkali-soluble pectin declined and ammonium oxalate soluble pectin increased as the mango lost its firmness and became soft. Polygalacturonase and cellulase activities of cell wall preparations increased markedly during ripening. The decline in alkali-soluble pectin and the increase in polygalacturonase activity correlated well with the loss of firmness. Alkali-soluble pectin declined slowly in ripe mangos stored at 4°C. This decline correlated with loss of firmness of the stored mangos. The cellulase activity of cell wall preparations from ripe mangos increased during 4°C storage and the increase correlated with the decrease in firmness.     

INFLUENCE OF VARIOUS SALTS IN THE COOKING WATER ON PECTIN LOSSES AND COOKED TEXTURE OF COWPEAS (VIGNA UNGUICULATA)

The effects of processing with solutions of calcium chloride, magnesium chloride, sodium bicarbonate and a local tenderizer known as ‘Kanwa’ (sodium sesquicarbonate) on pectin losses and cooked texture of cowpea seeds were investigated. For comparison, the cowpeas were processed in double distilled water and a local tap water. Analysis included total pectin, calcium and magnesium content, leached solids, texture and water absorption. The results show that CaCl₂, MgCl₂ and the local tap water increased firmness, Ca and Mg content in the cooked beans compared to distilled water; however, water absorption, leached solids and pectin solubilization were decreased by these salts. Kanwa and NaHCO₃ increased water absorption, leached solids and softness in the cooked beans and also increased pectin solubilization but decreased Ca and Mg when compared to distilled water or the other salts. These changes are discussed with respect to the effects of divalent and monovalent cations on the texture of the bean tissue.     

Vitamin Retention, Color and Texture in Thermally Processed Green Beans and Royal Ann Cherries Packed in Pouches and Cans

Thiamin (B-1) ascorbic acid (AA) and vitamin B-6 (B-6) were determined in pouched and canned green beans immediately after processing and after storage at 24–26°C or 38°C. AA and B-6 were also determined in pouched and canned cherries before and after storage at 24–26°C. There was significantly more B-1 and AA in drained pouched green beans, and more AA in drained pouched cherries than in canned ones. B-6 values in the solids of the pouched and canned products were not significantly different. These three vitamins were significantly reduced in drained pouched and canned green beans after storage at 38°C. B-6 was significantly reduced in the stored cherries. Compared to canned, the pouched products were brighter and firmer in texture.     

Studies on the quality characteristics of canned grapefruit segments

Summary. Segments prepared from grapefruits (var. Marsh Seedless) soften rapidly in the course of maturation of the fruit as evident from shear press readings for freshly peeled and canned segments. Storage of the fresh fruit for up to 9 days decreases firmness of the fresh segments and the loss in firmness increases with progressing maturation. Time and temperature of pasteurization affect significantly the firmness of the segments as well as their 'tendency to break'. the storage of the canned product, for up to 1 year had little effect upon drained weight, whereas texture and colour of the canned grapefruit segments were affected significantly.     

Improvements in Canned Lowbush Blueberry Quality

Individually quick frozen lowbush (wild) blueberries (Vaccinium angusrifolium) were canned with 0, 1500, or 3000 ppm calcium from chloride or lactate salts and 0, 0.25, or 0.50% citric acid in water. Physical and pH changes were measured at 0, 6, and 12 mo, and sensory evaluations were made at 3 and 9 mo post-canning. Calcium increased firmness and berry calcium content. Calcium chloride and citric acid reduced pH and increased hue angle and off-flavor; calcium lactate increased drained weight and pH but reduced hue. Response surface methodology predicted changes in calcium lactate-treated berries, but not CaCl₂-treated berries. Optimal conditions were 1200–1800 ppm calcium lactate at 3–6 mo storage.     

Effect of K Fertilization and Addition of Salts on the Texture of Canned Snap Bean Pods

Increases in pod K, obtained either by fertilization or direct addition to the can, resulted in less firm canned pods. Removal of soluble solids from pods prior to canning resulted in firmer pods. Pod K and texture were highly correlated, with the greatest changes in texture with changing K occurring below 2%K in pods on a dry weight basis. The effects of K and Na appeared due to a combination of Ca displacement and an enhancement of pectin degradation.