Quality characteristics of minimally processed leek packaged using different films and stored in lighting conditions

Since minimal processing of vegetables does not impede their capacity to react to external stimuli, this work sought to study the effect of lighting on minimally processed leek during storage. White and green cuts were processed separately and packaged using films with different permeability: a totally permeable PVC film and two P-Plus films: P-Plus 120 and P-Plus 90, with O₂ permeability of 8000 and 5000 cm³ m⁻² 24 h⁻¹ atm⁻¹ at 25 °C, respectively. All the packaged leek was stored at 4 °C for more than 26 days in two different conditions: in complete darkness and in light. Lighting caused an increase in stomatal aperture and respiratory rate. Thus, the white cut achieved atmospheres with higher CO₂ (10%) and lower O₂ (12%) content than samples packed in the same film kept in the dark. The green cut saw respiratory activity compensated by photosynthesis, and the atmosphere composition remained similar to atmospheric conditions until day 18. Lighting also affected the colour, accelerating the changes in appearance. Exposure to light had a negative effect on the quality parameters.     

Influence of exposure to light on the sensorial quality of minimally processed cauliflower

ABSTRACT:  The impact of lighting on minimally processed cauliflower packaged in 4 different film types (PVC and 3 P-Plus) has been measured and quantified. The effect on the sensorial quality of storage at 4 °C in darkness and partial or continuous lighting was evaluated. The gas concentrations in the packages and the weight losses were also determined. Atmosphere composition inside the packages depended on both the permeability of the film used for the packaging and exposure to light. Samples stored with lighting maintained the gaseous exchange between plant tissue and the atmosphere inside the packages for longer periods than in samples kept in darkness. This prompted a greater loss of water vapor as well as the development of atmospheres with low levels of O₂ and high levels of CO₂ in the samples packed with less permeable films. The most important aspect in sensory evaluation was color. In instrumental color evaluation, coordinates h * and L * were the main means for estimating color evolution. The presence of light accelerated browning in the cut zones. The development of abnormal coloring in these areas marked the end of shelf life for minimally processed cauliflower. Among the sensory attributes studied, color was the most affected by exposure to light. Samples packed in P-Plus 120 film displayed the lowest level of color deterioration in the cut zones. However, under lit conditions, the low permeability of this film caused atmospheres with very low O₂ contents and high CO₂ contents. These atmospheres produced a loss of texture and the development of off-odors.     

Quality changes of fresh-cut kohlrabi sticks under modified atmosphere packaging

ABSTRACT:  The aim of this study was to determine the effect of different gas compositions on quality attributes and shelf life of kohlrabi sticks stored in modified atmosphere up to 14 d at 0 °C. Two commercial films were tested: oriented polypropylene (OPP) and amide-polyethylene (amide-PE). As a control, a microperforated OPP film was used. In order to study the changes in metabolic activity by minimal processing, the respiration rate and ethylene production at 0 °C were monitored for both intact stems and sticks. Changes in color, chemical parameters, sugars and organic acid contents, and sensorial quality of kohlrabi sticks were evaluated. An initial ethylene production of sticks was 13-fold higher than that of intact stems; meanwhile CO₂ production was 2-fold higher. However after 4 d of storage, a similar respiration rate for stems and sticks was found. Also the ethylene production of sticks and stems was steady around 15 to 20 nL/kg^/h after 10 d. Kohlrabi sticks showed a little change in chemical parameters and very low weight losses during cold storage. Sticks under an equilibrium atmosphere of 7 kPa O₂ and 9 kPa CO₂ at 0 °C reached by amide-PE kept an acceptable sensorial quality for 14 d.     

Effect of film and temperature on the sensory, microbiological and nutritional quality of minimally processed cauliflower

The effect of atmosphere modification, generated using three different packaging films, on the quality of cauliflower minimally processed when stored at 4 or 8 °C for up 20 days was evaluated. The colour, texture, weight loss, sensory attributes, as well as microbial counts and sugars and ascorbic acid content were determined. The atmosphere generated with the perforated polyvinylchloride (PVC) film was hardly modified, whereas the other two films (non-perforated PVC and polypropylene films) originated changes in CO₂ and O₂ levels during storage. The different packaging conditions and storage temperature influenced yellowing. An increase in shear force was observed. Weight losses were below 5%. Mesophiles and Pseudomonas counts were below 7 log CFU g⁻¹, the populations being lower with film B and film C than with film A. Cauliflower maintained an acceptable appearance in all the films studied. Total sugars decreased about 27% after 20 days of storage, whereas ascorbic acid did not change.     

Quality Changes in Stored Raw Grated Beetroots as Affected by Temperature and Packaging Film

The effects of atmospheric composition and temperature on quality of grated beetroots were analyzed. Beetroots ( Beta vulgaris L.) were washed, grated and packaged in trays wrapped with two films of different gas permeabilities. Trays were stored at 0°C or 4°C for a week and then transferred to 20°C. Changes in atmospheric composition, pigment content, pH, titratable acidity and production of exudate were monitored. Shelf-life of grated beetroots was 7 d at 0°C and 3 to 4 d at 4°C. There was a notable decrease in pigment content during storage.     

Retention of Folate, Carotenoids, and Other Quality Characteristics in Commercially Packaged Fresh Spinach

ABSTRACT: The effect of storage temperature (4 °C, 10 °C, and 20 °C) on retention of folate, carotenoids, and other quality characteristics in commercially packaged fresh spinach were determined. Based on visual color and appearance, spinach was unacceptable after 8 d, 6 d, and 4 d at 4 °C, 10 °C, and 20 °C, respectively. Color differences (AE), chlorophyll degradation, fresh weight loss, and microbial populations increased at all storage temperatures and occurred more rapidly at higher temperatures. Peroxidase activity increased but was not significantly ( P > 0.05) affected by storage temperature. Lipoxygenase activity was unaffected by storage time or temperature. Substantial losses of nutrients occurred at each storage temperature. Only 53% of folate in packaged spinach was retained after 8 d, 6 d, and 4 d at 4 °C, 10 °C, and 20 °C, respectively. Carotenoid losses increased with temperature with only 54%, 61%, and 44%, respectively, of initial detected levels remaining. Vitamin and quality changes were unaffected by presence or absence of packaging.     

Overall Quality Throughout Shelf Life of Minimally Fresh Processed Fennel

ABSTRACT: The keeping quality of minimally fresh processed fennel up to 14 d at 0 °C under modified atmosphere packaging was studied. Samples of 1 cm³ diced fennel washed for 1 min with chlorinated (100 mg/L) water were placed in 35 μm oriented polypropylene (PP) bags or in PP baskets heat-sealed with unperforated or perforated (control) PP film. Changes in respiratory activity, ethylene emission, color, sugars content, chemical parameters, browning, decay, microbial growth, and sensory attributes were monitored. Respiratory activity in diced fennel was 1.5–fold higher than that for whole bulbs, and slight differences in ethylene emission between both whole and fresh processed fennel were found. A gas composition within both kinds of unperforated packages of about 11 to 13 kPa O₂ and 9 to 12 kPa CO₂ was reached. At the end of storage of fennel dices under this atmosphere, total plate counts were lower than legal limit for safe consumption. At any moment, neither physiological disorders nor decay developed. Although after 14 d a slight browning on the dices surface appeared, levels of sensorial attributes higher than acceptable for commercial purposes were reached.     

Microbial and sensory quality of vegetables for soup packaged in different atmospheres

Fresh prepacked vegetables for soup have become very popular on the Italian market, since they are already peeled, cut, washed and ready-to-use. The packaging and the modified atmosphere can prolong their shelf-life and maintain their hygienic, physicochemical and sensory characteristics during storage at + 4°C. The hygienic and sensory quality was evaluated by analysing microbial growth and atmosphere composition at the moment of packaging and at the end or the shelf-life of vegetables prepacked in air on under modified atmospheres, and by determining the browning or blackening of parsley and the loss of carrot exudates. A large number of different groups of microorganisms was found in raw vegetables. In spite of this high starting concentration of microbial flora, the prepackaging systems investigated did not seem to significantly influence their growth during vegetable storage at +4°C. No pathogenic microorganisms were isolated from the prepackaged vegetables. The hygienic quality was similar in all packaging systems used. However, the vegetables packaged in perforated. film kept their sensory characteristics better than those packaged in air or under a modified atmosphere.     

Impact of edible coatings and packaging on quality of white asparagus (Asparagus officinalis, L.) during cold storage

The effects of edible coatings and plastic packaging on quality aspects of refrigerated white asparagus spears were studied using two different experimental protocols. The first included four coating formulations based on carboxymethyl-cellulose and sucrose fatty acid esters, whey protein isolate alone and in combination with stearic acid, and pullulan and sucrose fatty acid esters, and an uncoated sample serving as a control. The second set consisted of four treatments; uncoated asparagus spears (control), coated with a carboxymethyl-cellulose formulation, packaged in plastic packaging and combination of coated and packaged asparagus spears. All products were stored at 4 °C and the quality parameters such as weight loss, texture, visual appearance, lignin and anthocyanins concentration, and colour were evaluated during their storage. Edible coatings exhibited a beneficial impact on the quality of asparagus by retarding moisture loss, reducing hardening in their basal part and slowing down the purple colour development. The plastic packaging had a remarkable influence in reducing weight loss and retarding hardening but its impact to the rest of the quality parameters was similar to that of the edible coatings. The combination of packaging and edible coating did not seem to offer any additional advantage on asparagus spears apart from the fact that the product had a brighter appearance at the middle part of the stem compared to the packaged spears alone.     

Shelf life of fresh‐cut green beans as affected by packaging systems

To reduce quality loss of fresh‐cut green beans, different packaging systems were studied. In particular, samples were packaged in micro‐perforated and no‐perforated films and stored at 5 °C; unpackaged fresh‐cut green beans were also stored at the same temperature as the control. Headspace gas concentrations, mass loss, sensory quality and microbial proliferation were monitored for about 3 weeks. Results confirmed that selection of proper packaging is of crucial importance to create conditions able to guarantee the maintenance of product quality. Shelf life of fresh‐cut green beans packaged in the no‐perforated film (polyethylene, 25 μm) and in two micro‐perforated films (polypropylene films with 7 and 4 micro‐holes per package) was higher (19.2, 18.13 and 17.7 days, respectively) than that of the control or samples packaged in the micro‐perforated film with 12 micro‐holes per package (16.5 days).     

Effect of plastic permeability and exposure to light during storage on the quality of minimally processed broccoli and cauliflower

The impact of lighting on minimally processed broccoli and cauliflower packaged in four different film types (PVC and three P-Plus) has been measured and compared. The effect on the sensory quality of storage at 4 °C in darkness and under lighting was evaluated. The gas concentration in the packages, pH, mesophilic counts and weight loss was also determined.Neither the type of film used for packaging nor the storage conditions led to changes in the evolution of pH or the microorganism count in broccoli and cauliflower. However, exposure to light stimulated stomatic opening facilitate the exchange of gases between the plant tissue and the atmosphere within the packaging. Thus, a considerable loss of water vapor was observed in the packages of both vegetables stored in the presence of illumination. Moreover, exposure to light stimulated respiratory activity so that for the cauliflower, the composition of the atmosphere within the packages varied depending on the permeability of the packaging film used and the storage conditions. However, in the case of the broccoli, the increase in respiratory activity due to the lighting was compensated by the photosynthetic activity which took place in these conditions, in such a way that the composition of the atmosphere inside the packs solely depended on the permeability of the film.This difference in the physiological response conditioned the most suitable kind of packaging film in each case. For cauliflower, in conditions of darkness, P-Plus 120 film proved the most suitable for preserving its sensory qualities, while under conditions of lighting, this film did not prove suitable due to its low permeability. However, in broccoli the different packaging films tested behaved in a very similar way whether stored under lighting or in the dark.     

Modified Atmosphere Packaging of Fennel

Fennel was washed on the butt‐end cut with ascorbic (1%) and citric (5%) acids and packed in polypropylene (PP) baskets sealed with PP film to generate a modified atmosphere. As a control, perforated PP was used. Storage conditions were 14 d at 0 °C followed by 4 d in air at 15 °C. Chemical and sensory quality attributes were monitored. No browning of external leaves developed. Modified atmosphere of 16 to 17% O² and 3 to 4% CO² was able to inhibit browning of the butt‐end cut, the main factor for keeping quality of fennel, but treatments with antioxidants did not. In all treatments, green color and firmness decreased, although under modified atmosphere the best results for keeping fennel quality were found.     

Influence of Packaging Films on the Sensory and Microbiological Evolution of Minimally Processed Borage (Borrago officinalis)

The atmospheres prevalent in borage packaged in 5 different films, together with different water‐vapor permeabilities of the films, determined the evolution of the visual and microbiological quality of borage. PVC films proved inadequate to extend the sensory quality since the samples packaged with the films were spoiled on day 9, whereas among the P‐Plus films, the least permeable film was the most adequate to extend the sensory quality of borage until day 15. For most of the treatments, no correlation between the microbial growth and changes in appearance was found. Thus, some treatments with a fair sensory evaluation had microbial counts higher than those allowed by the European legislation.     

Efficacy of citric acid against Listeria monocytogenes attached to poultry skin during refrigerated storage

The aim of this study was to evaluate the effect of citric acid washing on the growth of Listeria monocytogenes on poultry legs stored at 4 °C for 8 days. Fresh inoculated chicken legs were dipped into either a 0.052, 0.104 or 0.156  m citric acid solution for 5 min or distilled water (control). Surface pH values, sensorial characteristics and L . monocytogenes , mesophiles and psychrotrophs counts were evaluated. Legs washed with 0.156  m citric acid for 5 min showed a significant ( P  < 0.05) inhibitory effect on L . monocytogenes compared with control legs, being about 1.55 log units lower in the first ones than in control legs after 1 day of storage. Treatments with 0.156  m citric acid reduced bacterial growth and preserved reasonable sensorial quality after storage at 4 °C for 8 days.     

Evolution of Quality Characteristics of Minimally Processed Asparagus During Storage in Different Lighting Conditions

ABSTRACT:  The effect of different types of lighting (white, green, red, and blue light) on minimally processed asparagus during storage at 4 °C was studied. The gas concentrations in the packages, pH, mesophilic counts, and weight loss were also determined. Lighting caused an increase in physiological activity. Asparagus stored under lighting achieved atmospheres with higher CO₂ and lower O₂ content than samples kept in the dark. This activity increase explains the greater deterioration experienced by samples stored under lighting, which clearly affected texture and especially color, accelerating the appearance of greenish hues in the tips and reddish-brown hues in the spears. Exposure to light had a negative effect on the quality parameters of the asparagus and it caused a significant reduction in shelf life. Hence, the 11 d shelf life of samples kept in the dark was reduced to only 3 d in samples kept under red and green light, and to 7 d in those kept under white and blue light. However, quality indicators such as the color of the tips and texture showed significantly better behavior under blue light than with white light, which allows us to state that it is better to use this type of light or blue-tinted packaging film for the display of minimally processed asparagus to consumers.     

Spoilage of King Salmon (Oncorhynchus tshawytscha) Fillets Stored Under Different Atmospheres

ABSTRACT: King salmon ( Oncorhynchus tshawytscha ) packaged in air (AIR), nitrogen (N2), or 40:60 carbon dioxide:nitrogen (CO2N2) was stored (0 °C) for 18, 25, and 54 d, respectively. Air packs (AIR9) were also stored at 9 °C for 4 d. A quality index (QI) method was developed to monitor sensory quality of cooked salmon. First detection of spoilage was 1.5, 15, 15, and 21 d for AIR9, AIR, N2, and CO2N2 treatments respectively. Total aerobic and sulfide-producing bacteria, pH, drip loss, E_h, color, texture, ATP derivatives, trimethylamine, total volatile base nitrogen, thiobarbituric acid numbers, and peroxide values were determined. Only total aerobic counts and hypoxanthine were indicators of sensory deterioration across treatments and times.     

Potential role of Proteus-Providencia-Morganella species in quality deterioration of beef

Proteeae Isolation Medium of Hawkey et al. (1986) was effective for isolation and enumeration of Proteus-Providencia-Morganella spp. from beef and beef products. On this medium colonies were brown, surrounded by a zone of clearing. In an examination of retail beef samples packaged and stored in polyvinyl chloride (PVC) film, 5% contained these bacteria in a concentration of 10¹–10² cells per gram or cm². Isolates from retail beef samples included P. vulgaris, P. alcalifaciens, P. rettgeri, and M. morganii. None of the retail samples packaged and stored in high oxygen barrier (HOB) film contained detectable Proteus-Providencia-Morganella spp. Steaks inoculated with Proteus-Providencia-Morganella spp. and packaged and stored at 4°C in PVC film (15 days) or in HOB film (42 days) usually had a reduced count of Proteus-Providencia-Morganella spp. during storage. Slight increases in counts occurred on steaks inculated with P. vulgaris and P. rettgeri and stored at 4°C for 15 days in PVC film.     

Behavior of Listeria monocytogenes and Aeromonas spp. on fresh-cut produce packaged under equilibrium-modified atmosphere.

Storage experiments were conducted to follow the behavior of pathogens on fresh-cut vegetables (trimmed brussels sprouts, grated carrots, shredded iceberg lettuce, and shredded chicory endives) packaged under an equilibrium-modified atmosphere (EMA) (2 to 3% O2, 2 to 3% CO2, and 94 to 96% N2) and stored at 7 degrees C. As a comparison, fresh-cut vegetables were also packaged in a perforated high-barrier film (air conditions) and stored at 7 degrees C. In a first step, the shelf life of the vegetables in the two kinds of packages was determined by evaluating the microbiological quality as well as the sensorial quality (appearance, taste, and odor). In general, sensorial properties were faster in limiting the shelf life than microbiological criteria. The shelf life of the vegetables stored under an EMA was extended by 50% or more, compared with the air-stored vegetables. In a second storage experiment, the four fresh-cut vegetables were inoculated with a cocktail of psychrotrophic pathogens (Listeria monocytogenes, Aeromonas caviae [HG4]) and A. bestiarum (HG2) before packaging under an EMA and air at 7 degrees C. The inoculated pathogens were more influenced by the type of vegetable than by the type of atmosphere. No growth was detected on the brussels sprouts or on carrots (L. monocytogenes). Aeromonas spp. had a higher growth rate than L. monocytogenes on the shredded chicory endives and shredded iceberg lettuce at 7 degrees C.     

Optimizing Sensorial Quality of Iranian White Brine Cheese Using Response Surface Methodology

ABSTRACT: Response surface methodology was used to evaluate the effects of processing variables, such as ripening time (20 to 60 d), ripening temperature (6 to 10°C), level of rennet added (1 to 2 g/100 kg milk), and brine concentration (8% to 14%, w/v), on the sensorial quality of Iranian pickled cheese (feta type). Optimization of sensorial quality was performed by canonical analysis to derive the stationary point. Based on contour plots and canonical analysis, optimum conditions were ripening time 32 d, ripening temperature 8.3°C, level of rennet added 1.6 g/100 kg of milk, and brine concentration 11%. Predicted sensory score was 20.76 from maximum score of 25.     

Monitoring the sensorial and microbiological quality of pasteurized white asparagus at different storage temperatures

Changes in sensory quality and proliferation of pathogenic and spoilage microorganisms in pasteurized white asparagus were measured as a function of storage temperature. The main sensorial attributes studied with regard to storage time were the general appearance of the product, turgidity and package swelling. There was a significant correlation between the deterioration in sensorial quality and microbial evolution, which was even more marked at higher temperatures. After 13 days at 4°C, 6 days at 10°C, 5 days at 20°C and 84 h at 30°C organoleptic deterioration and, consequently, the end of shelf life were detected. A significant growth of spoilage flora was observed, which might be responsible for the drop in pH levels during the final period of analysis (from 6.3 to 3.5–4 until 148 h). There was greater lactic acid bacteria (LAB) growth as the temperature and CO₂ concentration increased, reaching a final concentration of approximately 10⁸ CFU g^?1 at all temperatures. We found no positive samples of Clostridium spp at 10 and 4°C. Among the species isolated at 20–30°C Clostridium septicum and in lower proportions Clostridium perfringens were encountered. The possible presence of Listeria monocytogenes was analyzed, but there were no positive samples in the final product. Pasteurized white asparagus maintains good organoleptic characteristics with a relatively long shelf‐life at low temperatures, which leads to an adequate acceptance among consumers. Copyright © 2006 Society of Chemical Industry