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.     

Microbiological quality and production of botulinal toxin in film-packaged broccoli, carrots, and green beans.

The production of toxin by a 10-strain mixture of proteolytic Clostridium botulinum in fresh produce packaged in polyethylene films with different oxygen permeability was determined. Broccoli florets, shredded carrots, and green beans inoculated with approximately 10(2) C. botulinum spores per g were placed in bags (1.4 kg per bag) composed of four films with different oxygen transmission rates (OTRs). Broccoli was packaged in bags with OTRs of 3 (7,000 cm3/m2/24 h) and 4 (16,000 cm3/m2/24 h), and green beans were packaged in bags with OTRs of 2 (6,000 cm3/m2/24 h) and 4. Broccoli and green beans in bags were compressed and heat-sealed. Shredded carrots were packaged in bags with OTRs of 1 (3,000 cm3/m2/24 h) and 3 and vacuum-sealed. Produce was stored at 4, 13, and 21 degrees C for up to 27 (broccoli) or 28 (carrots and green bean) days and analyzed periodically. At each sampling time, gas composition within the bags, pH of the produce microbial population (total aerobic and anaerobic microorganisms, lactic acid bacteria, psychrotrophic bacteria, yeasts, and molds), and the presence or absence of botulinal toxin were determined. Packaging material affected the quality of vegetables, especially broccoli stored at 4 and 13 degrees C. For example, broccoli was scored as "good" after 22 days at 4 degrees C when it was packaged in film with higher gas permeability (OTR of 4), whereas broccoli appeared to be in "poor" condition when packaged in film with lower gas permeability (OTR of 3). With the exception of lactic acid bacteria, packaging material did not noticeably influence the growth of microorganisms. Lactic acid bacteria grew better in broccoli packaged in bags with an OTR of 3 than in those with an OTR of 4 at all temperatures. Botulinal toxin was detected in broccoli packaged in bags with an OTR of 3 and stored at 13 degrees C for 21 days and in those with an OTR of 4 and 3 and stored at 21 degrees C for 10 days. All toxic samples were visibly spoiled. Toxin was not detected in produce packaged under any other test conditions.     

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.     

Larger serving size and seasoning’s role in consumer behaviors toward vegetables

A diet rich in vegetables provides many nutrients such as vitamins, minerals, and fiber; as a result, eating vegetables could reduce the risk of chronic diseases. However, very few Americans consume enough vegetables daily, and average intake falls significantly below national recommendations. This study aimed to examine the effectiveness of seasoning and increased portion sizes on vegetable consumption in a US adult population. An observational study was conducted in a commercial cafeteria that provided options of steamed or seasoned green beans, broccoli, cauliflower, and carrots (n = 890). The portion size was 8-oz, double the standard vegetable size (4-oz). Participants returned 527 surveys with information regarding vegetable choice, liking, and demographics. Leftover bowls were collected for waste analysis. According to binomial tests, significantly more people purchased the seasoned vegetables over steamed (p < 0.001); in detail, the same trend was observed with the purchasing data of seasoned green beans, broccoli, and cauliflower (p < 0.001 for each vegetable type). Vegetable likings were high and similar across all vegetables and cooking methods with an average of 7.3 (9 = like extremely). Overall, 8-oz (226.8 g) servings resulted in 16.59 mean g waste and 210.21 mean g of consumption. To conclude, cooking vegetables with herbs and spices was well accepted by the adult population as was a larger portion size.     

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.     

Physico‐Chemical and Structural Characteristics of Vegetables Cooked Under Sous‐Vide,Cook‐Vide,and Conventional Boiling

In this paper, physico‐chemical and structural properties of cut and cooked purple‐flesh potato, green bean pods, and carrots have been studied. Three different cooking methods have been applied: traditional cooking (boiling water at 100 °C), cook‐vide (at 80 and 90 °C) and sous‐vide (at 80 °C and 90 °C). Similar firmness was obtained in potato applying the same cooking time using traditional cooking (100 °C), and cook‐vide and sous‐vide at 90 °C, while in green beans and carrots the application of the sous‐vide (90 °C) required longer cooking times than cook‐vide (90 °C) and traditional cooking (100 °C). Losses in anthocyanins (for purple‐flesh potatoes) and ascorbic acid (for green beans) were higher applying traditional cooking. β‐Carotene extraction increased in carrots with traditional cooking and cook‐vide (P < 0.05). Cryo‐SEM micrographs suggested higher swelling pressure of starch in potatoes cells cooked in contact with water, such as traditional cooking and cook‐vide. Traditional cooking was the most aggressive treatment in green beans because the secondary walls were reduced compared with sous‐vide and cook‐vide. Sous‐vide preserved organelles in the carrot cells, which could explain the lower extraction of β‐carotene compared with cook‐vide and traditional cooking. Sous‐vide cooking of purple‐flesh potato is recommended to maintain its high anthocyanin content. Traditional boiling could be recommended for carrots because increase β‐carotenes availability. For green beans, cook‐vide, and sous‐vide provided products with higher ascorbic acid content.     

VITAMIN C AND β-CAROTENE IN FRESH AND FROZEN GREEN BEANS AND BROCCOLI IN A SIMULATED SYSTEM

The reduced ascorbic acid and β-carotene contents of “retail market-fresh” (RMF) and “fresh-frozen” (FF) green beans and broccoli in a simulated handling system were determined. Changes in ascorbic acid content in the two vegetables during a retail market period and frozen storage followed different patterns. In green beans, ascorbic acid content decreased during refrigerated storage for up to 7 days, but in broccoli there was a significant increase. Blanching resulted in a loss of approximately 40% of the ascorbic acid in broccoli. Ascorbic acid content of FF green beans stored at-20C for 16 weeks was approximately twice that in RMF green beans, but in FF broccoli stored under the same conditions it was only about half that of RMF broccoli. β-carotene content of green beans and broccoli did not change during either the retail market simulation of frozen storage and did not differ from that of fresh.     

Effect of Home Freezing and Italian Style of Cooking on Antioxidant Activity of Edible Vegetables

ABSTRACT:  In this study, we analyzed the modifications of antioxidant activity consequent to 3 typical home cooking practices (steaming, boiling, and microwave cooking) in fresh and home frozen vegetables. Six different vegetable species were examined: carrots ( Daucus carota L.), zucchini ( Cucurbita pepo L.), tomatoes ( Solanum lycopersicum L.), green beans ( Phaseolus vulgaris L.), peas ( Pisum sativum L.), and yellow peppers ( Capsicum annuum L.). All vegetables were conventional products and were analyzed in season to minimize differences due to agricultural practice and storage. Cooking and freezing are generally regarded as destructive to antioxidants, and this has fostered a belief among many consumers that raw vegetables are nutritionally superior to their frozen and/or cooked forms. In the current study, we provide evidence that this is not always the case.     

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.     

EFFECTS OF COOKING METHODS ON SENSORY QUALITIES AND CAROTENOID RETENTION IN SELECTED VEGETABLES1

The effects of induction boiling, conventional boiling and microwave steaming on the sensory qualities and carotenoid retention of broccoli, carrots, green beans and sweet potatoes were investigated. Significantly higher cooking yields were obtained for vegetables that were induction and conventionally boiled. No differences in the retentions of alpha‐carotene (α‐carotene), beta‐carotene (β‐carotene) and lutein/zeaxanthin were observed for vegetables by the cooking method, with the exception of β‐carotene retention in broccoli and sweet potatoes where retentions were higher for those that were induction boiled (90.3 and 86.1%, respectively) than those that were microwave steamed (62.2 and 66.4%, respectively). A trained panel judged the color scores of three vegetables by the cooking method as similar. The mean flavor scores (1 = extremely bland; 9 = extremely intense) for three vegetables that were conventional (4.7–5.4) and induction (5.3–5.5) boiled were lower than those that were microwave steamed (5.9–7.0). The mean texture scores (1 = extremely mushy/tender; 9 = extremely firm/tough) for all induction‐boiled (5.0–6.0) vegetables were higher than those that were conventionally boiled (3.4–5.2) and lower than those that were microwave steamed (5.1–6.6).     

Influence of commercial freezing and storage on vitamin C content of some vegetables

Vitamin C levels of commercially frozen okra, potatoes, green beans, broccoli, spinach and peas, including the impact of processing and storage, were studied. Depending on the vegetable type, prefreezing operations caused a 19.1–51.5% decrease in the initial vitamin C levels. The freezing process alone did not influence the vitamin levels except in the cases of green beans and spinach. Total losses (%) were between 27.6 and 57.9 for the vegetables at the end of commercial frozen storage (6 months). All the data obtained from this study confirmed that, depending on the vegetable type, prefreezing operations have a major impact on the vitamin C contents and this influence persists in the frozen storage.     

A comparison of the vitamin C content of fresh and frozen vegetables

This study, using vitamin C (ascorbic acid) as ‘marker’, allowed a direct comparison of the nutritional quality of fresh vegetables at various stages of distribution and storage, with the same vegetable commercially quick-frozen and stored deep frozen for up to 12 months. The nutrient status of frozen peas and broccoli was similar to that of the typical market-purchased vegetable and was superior to peas that have been stored in-home for several days. Fresh peas and broccoli retained their quality for up to 14 days when stored under chill conditions. The nutrient status of frozen whole green beans and frozen carrots, with no loss on freezing, was similar to the fresh vegetable at harvest. Frozen spinach also compared reasonably well with the harvested fresh vegetable and was clearly superior to all market produce.     

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.     

Influence of blanching and low temperature preservation strategies on antioxidant activity and phytochemical content of carrots, green beans and broccoli

The objective of this study was to investigate the effect of blast freezing and blanching in combination followed by chilling, on the antioxidant activity (ARP), phenols, ascorbic acid and colour of broccoli, carrots and green beans. No significant changes (p > 0.05) in ARP of blanched frozen (BLFR) broccoli, carrot and green beans were observed. In contrast, UBFR (unblanched frozen) treatments caused a significant decrease (p < 0.05) in ARP and ascorbic acid content of vegetable samples. BLFR treated samples had better retention of antioxidant activity and ascorbic acid as compared to UBLR counterparts at chill storage (4 °C) for 7 days. However, no significant changes were observed in phenol content for all vegetables. Ascorbic acid decreased exponentially for both blanched and unblanched samples. The reaction rate constant (k) increased from 1.06 × 10⁻¹ day⁻¹ to 1.17 × 10⁻¹ day⁻¹ for blanched and unblanched broccoli florets and from 4.6 × 10⁻³ day⁻¹ to 1.98 × 10⁻¹ day⁻¹ for blanched and unblanched carrots during 7 days storage. Result presented here indicates greater stability of nutritional parameters for BLFR samples compared to UBFR samples during 7 days storage at 4 °C for all vegetables.     

Nitrate and Nitrite Methods of Analysis and Levels in Raw Carrots, Processed Carrots and in Selected Vegetables and Grain Products

Methods for quantitative estimation of nitrate and nitrite were compared. Levels of these ions were measured in vegetables and grain products and effects of processing on nitrate and nitrite levels in carrots were measured. These data allow more accurate estimation of ingestion levels and suggest means to reduce exposure to these ions. High performance liquid chromatography (HPLC) had better precision and recoveries than either a classical Cd-Griess method nitrate or a Griess method for nitrite. Nitrate concentration by HPLC varied greatly within and between vegetables, ranging from 1 μmol/100g in mushrooms to 5000 μmol/100g in celery and averaging 9.7 ± 4.4 μmol/100g in grains. Nitrate levels in vegetables sold as “organic” were not different (p<0.05) from conventional vegetables. No nitrite was detected in either vegetables or grains. Nitrate was unevenly distributed in carrots with the core having the most. Storage of carrots at -18°C for 10 wk did not alter nitrate levels and no nitrite developed. Fifty-seven percent of nitrate was leached into cooking liquid when frozen carrots were boiled. Thirty-two percent of nitrate was lost during canning and 47% of the remainder was in the liquid. No nitrite developed during 10 wk of canned storage.     

Selection and use of autochthonous mixed starter for lactic acid fermentation of carrots, French beans or marrows

Strains of Leuconostoc mesenteroides, Lactobacillus plantarum, Weissella soli/Weissella koreensis, Enterococcus faecalis, Pediococcus pentosaceus and Lactobacillus fermentum were identified from raw carrots, French beans and marrows by partial 16S rRNA gene sequence. L. plantarum M1, Leuc. mesenteroides C1 and P. pentosaceus F4 were selected based on the rates of growth and acidification in vegetable juice media, and used as the autochthonous mixed starter for the fermentation of carrots, French beans or marrows. An allochthonous starter, consisting of the same species, was also used for fermentation. A two-step fermentation process (1 day at 25 degrees C and 7 days at 15 degrees C) in brine (1% w/v) followed by storage at room temperature in olive oil until 40 days was set up. Unstarted vegetables subjected to the same treatments were used as the controls. Cell numbers of lactic acid bacteria in the started vegetables were ca. 10,000 (autochthonous starter) and 1000 (allochthonous starter) times higher than unstarted samples throughout the process. When fermented with the autochthonous starter, carrots, French beans or marrows were characterized by the rapid decrease of pH (<4.5), marked consumption of fermentable carbohydrates, and inhibition of Enterobacteriaceae and yeasts. Fermentation with the allochthonous starter did not acidify and inhibit bacteria and yeasts so rapidly. After 40 days, carrots, French beans and marrows fermented with the autochthonous starter had significantly (P<0.05) higher total concentration of vitamin C (ascorbate+dehydroascorbate) with respect to those fermented with the allochthonous starter and, especially unstarted vegetables. The same was found for the indexes of color. Firmness of both started vegetables was higher than unstarted vegetables. Sensory analysis differentiated started vegetables. Carrots and French beans fermented with the autochthonous starter were, especially, appreciated for fragrance. Appearance was the sensory attribute that mainly distinguished marrows fermented with the autochthonous starter.     

Impact of the industrial freezing process on selected vegetables -Part II. Colour and bioactive compounds

In the present study, the impact of the different steps (i.e. blanching, freezing, storage following the industrial freezing process and the final cooking prior to consumption) of the industrial freezing process was evaluated on colour, chlorophylls, lutein, polyphenols and ascorbic acid content of asparagus, green beans and zucchini. In addition, the domestic boiling of raw samples was compared with the boiling of frozen storage vegetables.Results showed that the blanching treatment retained phytochemicals in all studied green vegetables and the frozen storage up to 2 months did not negatively affected phytochemicals, in particular lutein and flavonoids in almost all samples. On the contrary, colour significantly changed during blanching and frozen storage. The changes of b* (yellowness) and the shift of H° (hue angle) were not coherent with the increase of pheophytin. In addition, the greenness (− a*) was found to increase with the exception of boiled samples in all vegetables. Generally, in boiled frozen vegetables there was a better or comparable retention of bioactive compounds with respect to raw ones, and this was especially true for green beans and zucchini. Colour changes after cooking did not exhibit the same trends among vegetables, being more remarkable for frozen asparagus in comparison with those boiled from raw, but overall comparable for green beans and zucchini.In conclusion, the overall results of the present study suggest that, when the industrial freezing process is well performed, the boiled frozen vegetables do not have a lower nutritional value than the fresh ones.     

Effect of Freezing, Thawing, Drying, and Cooking on Carotene Retention in Carrots, Broccoli and Spinach

Effects of freezing, thawing, cooking and drying on carotene retention of carrots, broccoli and spinach were evaluated. Relative differences in carotene retention among these vegetables were compared. Dehydration, regardless of drying method, significantly reduced carotene in these vegetables. Carotene contents of fresh, vacuum and microwave dried samples for carrots, broccoli and spinach were 989, 459, 368; 106, 43, 40; and 455, 325, 314 μg/g, respectively. Lag time after thawing decreased mean carotene of vegetables significantly in a quadratic manner. Degradation of carotene was severe 6 hr after thawing, Cooking did not affect carotene and cooked samples contained 2.0, 2.9, and 1.2 times more carotene than the respective dehydrated vegetables. Destruction of carotene was relatively lower when initial concentrations were low.     

Vitamin C losses in some frozen vegetables due to various cooking methods

Frozen spinach, peas, green beans and okra were commercially cooked in three different stewpans (double based stainless steel, teflon, pyrex) with and without thawing. The vitamin C levels were effected both by cooking methods and stewpans. Frozen peas were found to be the least (3.5% loss), and frozen green beans were found to be the most (19.6% loss) effected vegetables by thawing. In all of the stewpans, double based stainless steel pan retained more vitamin C than the others. While boiling spinach, peas, green beans, and okra without thawing resulted 46.5, 25.2, 18.2, and 21.6% vitamin C loss in double based stainless steel pan, boiling them in pyrex pan resulted 58.5, 36.0, 42.1, and 28.2% vitamin C loss, respectively. Besides, the losses in cooking processes were accelerated in thawed vegetables with the same tendency; that is more destruction occurred in samples boiled in pyrex pan (60.3% loss in spinach, 40.8% loss in peas, 48.4% loss in green beans, and 41.6% loss in okra). According to the results, it was found that thawing before cooking is useless and causes more vitamin C loss. Therefore, frozen vegetables must not be thawed before cooking. In order to prevent vitamin C from destruction, using double based stainless steel pan, minimum amount of water and cooking of frozen vegetables are recommended.     

不同烹饪与冷却方法对冷配送中式快餐中3种绿色蔬菜品质的影响

目的探究烹饪及冷却方法对冷配送中式快餐中绿色蔬菜的品质影响。方法以西兰花、青椒及青刀豆为研究对象,分别对其进行热烫、微波、急炒烹饪,再分别进行自然冷却、冷风冷却及冷水冷却,检测其失重率、亚硝酸盐含量、叶绿素含量及可滴定酸含量等指标的变化。结果热烫的西兰花重量不减反增,青刀豆及青椒急炒时失重率最高。3种蔬菜热烫后使用不同的方法冷却,其亚硝酸盐含量均上升。所有处理都使3种蔬菜中的叶绿素含量显著降低。冷却方式不会影响3种蔬菜中的可滴定酸含量,而烹饪方式却有影响。结论烹饪及冷却方式对中式快餐中的绿色蔬菜品质有一定的影响,且与蔬菜品种有关。