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.     

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.     

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.     

Frozen Carrots Texture and Pectic Compotients as Affected by Low-Temperature-Blanching and Quick Freezing

Carrots preheated for 2 hr at 60°C and then cooked became firmer than raw or cooked carrots. After preheating, the amount of high methoxyl pectin decreased, and low methoxyl pectin increased. Firmness of carrots decreased through freezing then thawing, but preheated carrots retained firmer texture than those blanched in boiling water. Quick-freezing resulted in better texture than slow-freezing. Loss in texture was accompanied by release of pectin. Slow-freezing accelerated release of pectin as compared to quick-freezing. Preheated carrots were slower in release of pectin. The degree of esterification of pectin substances in raw carrots decreased during preheating, freezing and thawing. Cell damage in quick frozen carrots was slight. Optimum preheating occurred with 30 min at 60°C or 5 min at 70°C. Preheating and then quick freezing were effective in improving texture of frozen carrots.     

Influence of Acidification on Texture of Canned Carrots

Texture of acidified canned carrots was evaluated using a shear compression procedure. Carrots canned with as little as 0.77% gluconic acid in the brine retained firmer texture than those packed without acid. Softening phenomena of acidified carrots do not appear to be consistent with a two substrate first order rate expression model.     

Calcium and Oxalate Ions Effect on the Texture of Canned Apricots

SUMMARY– Softening of canned apricots was accompanied by increase in soluble pectin and syrup viscosity. Calcium ions have the ability to decrease, to some extent, the movement of pectic material from the fruit to the syrup. This might be explained by the ability of calcium ions to make a bridge between polygalacturonic acid units, thus producing larger molecules which bind the cells together at the middle lamella. Added oxalate ions removed calcium from pectin in the cell wall, causing an increase in water-soluble pectin in the syrup and softening of texture. The mineral contents of canned apricots from three growing areas were determined by flame spectrophotometry. Low potassium in the fruit seems to be related to low pH in the cell sap, causing hydrolysis of pectic materials through hydrolysis ion catalysis and softening during heat processing and storage.     

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.     

Effects of Calcium, Sucrose, and Aging on the Texture of Canned Great Northern Beans (Phaseolus vulgaris, L.)

Factors affecting hardness of canned Great Northern beans (Phaseolus vulgaris, L.) were investigated. Addition of calcium significantly increased the hardness of processed beans; however, the calcium content usually found in hard culinary water supplies did not cause good quality beans to be unacceptably hard when processed. Firmer processed beans had a higher calcium uptake and lower water absorption. Sucrose increased the hardness of processed beans. Sucrose and calcium were synergistic in their firming action. Beans stored at high temperature and humidity for a prolonged period of time became firmer when processed and more sensitive to calcium hardening and to the synergistic effects of calcium and sucrose.     

EFFECTS OF CULTIVARS, BLANCHING TECHNIQUES, AND COOKING METHODS ON QUALITY OF FROZEN GREEN BEANS AS MEASURED BY PHYSICAL AND SENSORY ATTRIBUTES

Effects of cultivars, blanching techniques, and cooking methods on the color, texture, and sensory characteristics of frozen green beans were investigated. Provider beans were firmer than the Contender cultivar following frozen storage and cooking when evaluated instrumentally and by a sensory panel. Microwave-blanched beans were harder according to Instron measurements, and sensory scores for firmness and toughness were higher than beans blanched by boiling water or steam. Green beans blanched or cooked by microwaves had grassy aromas and strong off-flavors that were not detected in those blanched or cooked by conventional methods. Microwave cooked beans were greener and firmer than those conventionally cooked.     

Essential Elements and Cadmium and Lead in Fresh, Canned, and Frozen Green Beans (Phaseolus vulgaris L.)

Sixteen essential elements, cadmium and lead were determined in fresh, canned, and frozen green beans (Phaseolus vulgaris L.). Samples were taken during processing to determine where changes in element content occurred. Canned green beans contained lower concentrations of calcium, copper, iron, magnesium, manganese, phosphorus, potassium, and zinc, but had higher amounts of chloride, nickel, and sodium than fresh beans. No change in silicon was observed. Iron, phosphorus and potassium were lower in frozen than in fresh green beans, but calcium, sodium and zinc were higher. There was no change in chloride, copper, magnesium, manganese and silicon due to freezing. Element retention ranged from 51 - 100% for canned and from 73 - 171% for frozen green beans.     

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.     

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.     

STABILIZATION OF CARROT JUICE BY DILUTE ACID TREATMENT

SUMMARY– A problem arises if juice extracted from raw carrots is heated to about 180° before or during conventional canning practices. An unsightly, unappetizing coagulum forms and the color of the juice precipitates with the coagulum. The coagulum is not as evident if the carrots are heated 5 min in water prior to juice extraction, but the juice loses some of its bright-orange color. The canned juice extracted from carrots heated 5 min in a .05 N acetic acid solution does not coagulate and the amount of juice which can be extracted from the carrots is 3.3% greater than that from carrots heated 5 min in water. The centrifuged juice from acid-treated carrots had a brighter orange color than juice from the water-treated carrots. The color notation was Rd, 23.7, a, 30.4 and b, 34.8 for juice from acid-treated carrots compared with a notation of Rd, 19.2, a, 24.4 and b, 31.4 for the juice from water-treated carrots. The canned juice extracted from raw carrots had less pectic substances and starch and about the same amount of protein as the canned juice from the carrots heated in water or .05 N acetic acid, but the canned juice from raw carrots coagulated. The juice from carrots heated in acid does not form a coagulum and maintains its orange color, probably because of the action of the heat and acid on the protoplasmic liquid of the cell before or immediately after the cell is ruptured.     

Firmness and Cell Wall Characteristics of Pasteurized Jalapeño Pepper Rings Affected by Calcium Chloride and Acetic Acid

Pepper rings packed in brine containing CaCl₂ were firmer, had higher bound calcium, chelator soluble pectin and pectin DE, and less water-soluble pectin (WSP) than peppers packed in brine containing no CaCl₂. Pepper rings packed in low acid brines (1% and 1.2% acetic acid) were firmer and had less WSP than those packed in high acid brine. Those samples (4% acetic acid) resulted in softening and pectin solubilization, but CaCl₂ resulted in less softening. Monosaccharide composition of cell walls was not affected by CaCl₂ or acetic acid. Firmness retention in CaCl₂ treated samples was probably due to greater association between calcium ions and pectic substances, which resisted acid hydrolysis.     

Characteristics of Cell Wall Structure of Green Beans During Controlled Freezing Point Storage

Controlled freezing-point storage means that the storage temperature is in a non-freezing temperature zone between the freezing point of water and food. It has been demonstrated that controlled freezing-point storage can prolong the storage-life of fresh food. Green beans (Phaseolus vulgaris L.) have been planted extensively in the northeast region of China and harvested seasonally. Degradation of cell wall polysaccharides has greatly affected the texture properties of the green bean cell walls. During controlled freezing-point storage, activities of cellulase, pectin methyl esterase, and polygalacturonase were inhibited effectively. It resulted in a slow degradation of cellulose and pectin, less expansion of the cell wall, and less dissolution of pectin layers. As a result, the web structure of the cell wall was preserved. At controlled freezing temperature, the hardness of green beans decreased slightly. Homogalacturonan of chelate pectin was degraded into galacturonic acid, and the side chains of the soluble alkali pectin were degraded into arabinose and galactose. At the later stage of controlled freezing-point storage, the web structure of the cell wall polysaccharides was destroyed. However, the pectin degradation in the green beans was inhibited significantly during controlled freezing-point storage.     

Quality Evaluation of Pinto Beans and Green Beans Canned in Two Large Reusable Containers

ABSTRACT: As an alternative to standard metal cans, 2 large-scale, reusable containers were constructed with volumetric capacities 3.6 to 3.8 times greater and process times 1.36 to 2.05 times longer than a nr 10 can. Effects of increased process time on product quality were measured by conducting objective color and texture evaluations on green beans and pinto beans canned in both containers. Green beans and pinto beans had comparable texture profiles to beans processed conventionally in nr 10 cans. The color of green beans also was comparable; the color of pinto beans was darker, possibly due to contact with the metal container. Color and texture differences were minimal between inner and outer product layers.     

Prevalence of Clostridium botulinum and thermophilic heat-resistant spores in raw carrots and green beans used in French canning industry

Two categories of vegetables (carrots and green beans) that are widely used in the manufacture of canned food were surveyed for their spore contamination. Samples were recovered from 10 manufactures spread over all producing areas in France. Two samples over 316 raw vegetables collected were found positive for botulinum neurotoxin producing Clostridia spores as tested by PCR-based GeneDisc assay. Both positive samplestested positive for the type B neurotoxin gene (bont/B). In parallel, heat-resistant spores of thermophilic bacteria that are likely to be associated with canned food spoilage after prolonged incubation at 55 °C were surveyed after specific enrichment. Prevalence varied between 1.6% for Moorella thermoacetica/thermoautotrophica in green bean samples and 8.6% for either Geobacillus stearothermophilus or Thermoanaerobacterium spp. in carrot samples. Vegetable preparation, e.g. washing and edge cutting, considerably reduced spore contamination levels. These data constitute the first wide examination of vegetables specifically cultivated for industrialpurposes for their contamination by spores of thermophilic bacterial species.     

Blanching Effects on the Chemical Composition and the Cellular Distribution of Pectins in Carrots

ABSTRACT: Carrots were blanched using 4 time-temperature combinations. Galacturonic acid and sugar contents of pectin extracts were determined, and immunocytochemistry experiments elucidated changes in the cell membrane. Blanching decreased galacturonic acid and total sugar contents for all treatments. Carrots subjected to high-temperature short-time (HTST) blanching contained more total galacturonic acid and total sugars in pectins than carrots blanched for a long time at low temperatures (LTLT). Similar trends were observed for methylated pectin and neutral sugars. Immunocytochemistries showed separation of the 3-way junction of cell walls, and LTLT-blanched carrots showed higher levels of JIM 7-labeled pectin (1.6 × 10⁻⁴ particles/nm²) than HTST-treated carrots (5.9 × 10⁻⁵ particles/nm²).     

Development of a method to measure dietary fibre in oranges

A method to measure dietary fibre in oranges has been developed. Pectin was extracted from the food sample using heat, acid and a cation-exchange resin. This was followed by enzymic digestions, using pepsin and pancreatin, of the remaining residue. Optimal levels of resin, pH, time and temperature for maximum pectin extraction were found. Optimal levels of enzymes and pH for maximal enzyme digestion was also found. Other food products tested for dietary fibre content were: cauliflower, oranges, pole beans, carrots and whole wheat flour. Values found were greater than those for other fibre analyses; however, most other methods fail to measure the water-soluble indigestible components, such as pectin.     

Inactivation of peroxidase and lipoxygenase in carrots, green beans, and green peas by combination of high hydrostatic pressure and mild heat treatment

The efficiency of high hydrostatic pressure (HHP) with the combination of mild heat treatment on peroxidase (POD) and lipoxygenase (LOX) inactivation in carrots, green beans, and green peas was investigated. In the first part of the study, the samples were pressurized under 250–450 MPa at 20–50 °C for 15–60 min. In the second part, two steps treatments were performed as water blanching at 40–70 °C for 15 and 30 min after pressurization at 250 MPa and 20 °C for 15–60 min. Carrot POD was decreased to 16% residual activity within the first 30 min at a treatment condition of 350 MPa and 20 °C and then it decreased to 9% at 60 min. When the carrots were water blanched at 50 °C for 30 min after HHP treatment of 250 MPa at 20 °C for 15 min, 13% residual POD activity was obtained. For green beans, the most effective results were obtained by two steps treatment and approximately 25% residual POD activity was obtained by water blanching at 50 °C for 15 min after pressurization at 250 MPa and 20 °C for 60 min. An effective inactivation of POD in green peas was not obtained. For carrots, LOX activity could not be measured due to very low LOX activity or the presence of strong antioxidants such as carotenoids. After pressurization at 250 MPa and 20 °C for 15 or 30 min, water blanching at 60 °C for 30 min provided 2–3% residual LOX activity in green beans. The treatment of 250 MPa for 30 min and then water blanching at 50 °C for 30 min provided 70% LOX inactivation in green peas.