Article

Nutritional and sensory evaluation of ready-to-eat salads during shelf life

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Abstract

The evolution of the antioxidant and sensory properties of six commercially available ready-to-eat salads, rocket, iceberg lettuce, baby lettuce, lamb's lettuce, curly endive and radicchio, was studied throughout the shelf life. Both the storage under modified atmosphere and in unsealed pouch in a domestic refrigerator were considered and compared. Ascorbic acid, total phenolics content and antioxidant capacity were chosen as the most representative nutritional parameters for this purpose. The data obtained were analyzed by Principal Component Analysis (PCA). Radicchio, lamb's lettuce and rocket showed an initial higher content of the quality parameters studied and demonstrated a better resistance to air exposure than the other salads, being ascorbic acid the most affected parameter. Modified atmosphere packaging demonstrated to be a very useful and reliable technology to extend nutritional and sensory properties during the shelf life period for all the vegetables studied.

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... On the other hand, RTESs are expensive compared to the original products, being affordable for medium-high purchasing power consumers [5,6]. In some previous reports, key points and factors during RTES processing to obtain high-quality products have been addressed [1,10,25]. However, as far as we know, no information is available in the literature regarding factors determining consumers' purchasing behaviour of RTESs, their consumption patterns and frequencies and the evolution of RTES quality properties during storage in domestic refrigerators. ...
... Finally, general appearance decreased after day 4 in all ingredients of RTESs, although all of them had scored higher than six at day 7 (8.33 ± 1.00, 7.56 ± 0.73, 6.67 ± 1.41 and 6.67 ± 1.94 for green escarole, corn salads, radicchio and white escarole, respectively), still over the limit of acceptance for consumption ( Figure 3D). Accordingly, Preti and Vinci [25] reported losses of general appearance in ready-to-eat salads after four days of storage. ure 3C). ...
... Finally, general appearance decreased after day 4 in all ingredients of RTESs, although all of them had scored higher than six at day 7 (8.33 ± 1.00, 7.56 ± 0.73, 6.67 ± 1.41 and 6.67 ± 1.94 for green escarole, corn salads, radicchio and white escarole, respectively), still over the limit of acceptance for consumption ( Figure 3D). Accordingly, Preti and Vinci [25] reported losses of general appearance in ready-to-eat salads after four days of storage. ...
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Ready-to-eat fresh-cut salads (RTESs) are fresh-cut vegetables that have been minimally processed and remain alive until consumption. A survey with 297 respondents was performed, showing that most respondents consumed RTESs composed of various vegetables once or twice a week. The most important items for consumers’ RTESs purchasing intention were the expiration date and the absence of exudates and brown and dehydrated leaves, while after storage in domestic refrigerators, the most important item for consumption refusal was the presence of strange odours. On the other hand, among the non-consumers of RTESs, the most important reason for not buying this kind of produce was the use of plastic packaging. Microbiological analysis of RTESs (composed of corn salads, radicchio and escarole leaves) showed that moulds, yeasts and psychrophilic aerobic microflora remained unchanged from buying to the expiration date, while increases occurred in mesophilic aerobic microflora, although all of them were within safety levels for consumption even after 4 days of the expiration date. Finally, total phenolics and antioxidant activity were higher in corn salads followed by radicchio and escarole leaves, and generally, no significant changes occurred in the bioactive compounds of RTESs during storage in domestic refrigerators.
... Increased total phenolic content was reported on the expiration date of the combination of lettuce and chives in summer. On the other hand, decreased phenolics were reported for baby lettuce, curly endive and iceberg lettuce after 4 days of storage at 4 • C, while no significant differences among phenolic content were reported for radicchio, rocket and lamb's lettuce [53]. This may be attributed to the packaging conditions in bagged samples due to the modified atmosphere packaging of these vegetables. ...
... Higher antioxidants (by FRAP assay) on product expiration date were observed in winter for the combination of lettuce with cabbage and in summer for the plain rocket. Preti and Vinci [53] reported increased antioxidants compounds (by DPPH assay) on the expiration date of baby lettuce, curly endive, lamb's lettuce, rocket and radicchio salads. The majority of the combinations of lettuce with other ingredients showed higher H 2 O 2 and MDA levels on the expiration date in both seasons. ...
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When minimally processed vegetables reach their expiration date, expose an increased microbial load. This includes mainly spoilage microorganisms but also foodborne pathogens, thus affecting the quality and safety of highly consumed ready-to-eat salads. A total of 144 ready-to-eat salads from the Cypriot market were analyzed in an attempt to determine the effects of the expiration date on the microbial load and plant metabolic variables of the salads. Possible correlations between them were also investigated for the first time. Furthermore, the impacts of the season (winter, summer), salad producing companies and type of salad and/or their interactions with the tested parameters were investigated. Results revealed that the microbial load (mainly spoilage microorganisms, such as Pseudomonas spp., yeasts and molds) increased towards the end of the shelf life. The microbial load was differentiated among the five salad producers and/or the salad types, highlighting the importance of a common and safe sanitation-processing chain in the preparation of ready-to-eat salads. Summer was the season in which Escherichia coli counts were found to be higher for plain lettuce, while Staphylococcus spp. was increased numbers for the lettuce+endive/radicchio, lettuce+rocket and lettuce+chives type of salads. Additionally, an increased Staphylococcus spp. was observed for plain rocket salads in winter. All samples examined were found negative for Salmonella enterica and Listeria monocytogenes. Moreover, carbon dioxide production and damage indexes (hydrogen peroxide and lipid peroxidation) increased on expiration date on both winter and summer seasons, indicating plant tissue stress at the end of shelf life. These findings indicate that the expiration date and relevant shelf life of processed vegetables are important parameters to be considered when postharvest management is applied to these products, ensuring safety and quality.
... Interestingly, TPC increased on the third day of storage in all samples and then either remained constant or increased further. The results are in accordance with the report of Preti and Vinci (26) who measured equivalent content of phenolics in lamb's lettuce during a 7-day refrigerated storage. Similarly, Myojin et al. (29) determined increased TPC of shredded red and white cabbage during a 7-day refrigerated storage and Santos et al. (11) reported a comparable TPC turnover of fresh-cut aromatic herbs. ...
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Lamb's lettuce is a popular winter salad, often grown in private vegetable plots, small local farms or in intensive vegetable production. It is usually marketed as a ready-to-eat produce in supermarkets. The aim of the study was to evaluate the changes in biochemical composition and degradation of bioactive compounds during consumer-relevant time of home-grown and store-bought Valerianella locusta “Vit” salad. Primary metabolites, assimilatory pigments as well as secondary metabolites were monitored during 1 week of refrigerated storage. Home-grown lamb's lettuce exhibited highest levels of total sugars, total organic acids, vitamin C, and total phenolic content as well as enhanced levels of most individual phenolic compounds and chloroplast pigments. Locally produced samples of lamb's lettuce also contained high levels of analyzed bioactive components. All samples retained most bioactive components during the entire period of refrigerated storage. The results underline the instability of vitamin C during refrigerated storage of lamb's lettuce and pinpoint this parameter as being the most affected by storage.
... 45%, consistently with the GS influence on antioxidant capacity of fresh endive produce (D'Acunzo et al., 2016). One week storage ORAC loss of curly cultivars was comparable to the antioxidant capacity decrease (over 6%) as measured by other chemical methods in packaged curly endives (Preti and Vinci, 2016). The smooth 'Parmance' had slightly (but significant) lower ORAC values than the other cultivars, supporting a genotype modest incidence on this parameter as observed for fresh endives (D'Acunzo et al., 2016). ...
Article
The influence of cultivar (CV), growth site (GS) and storage time (ST) on the quality of minimally processed endives was investigated by targeting curly and smooth-leafed cultivars, which were grown in two planting areas (Fiumicino and Fucino) and bagged in modified atmosphere at fixed conditions. The changes of antioxidant properties were examined at one and seven days post-packaging by measuring both contents of total flavonols (Fol), flavonoids (Fid), carotenes (Car) and chlorophylls (Chl) and the antioxidant capacity (AOC) through chemical (ORAC) and erythrocyte-based methods (CAA-RBC and hemolytic assays). Referring to one day of storage, curly types differed from smooth ones due to the total contents of Fid (341.0-891.7 vs 312.3-572.3 mg kg −1 CE), Fol (312.0-452.7 vs 194.3-520.3 mg kg −1 QE), Car (72.4-110.5 vs 7.3-38.8 mg kg −1) and Chl (342.7-824.6 vs 276.5-490.4 mg kg −1). CV and GS majorly affected the content variation, whilst ST did not exert any impact on the amounts of pigments (Chl and Car). As for the AOC at one day post packaging, curly and smooth endives respectively showed ORAC mean values of 5045 ± 2287 and 4822 ± 573 mmol kg −1 TE, CAA-RBC units of 27.5 ± 5.4 and 21.1 ± 2.6 μmol kg −1 QE, and hemolysis percentage of 62.5 ± 5.9 and 57.9 ± 10.9. The three factors acted on the AOC variation at the single level and CV x GS was the most affecting interaction. The ORAC values showed positive correlations with Fid, Fol and Chl contents as well as those of CAA-RBC vs Fid and pigment amounts, while only the Fol raise agreed with increased anti-hemolytic effects. Positive correlations among the AOC assays were significant just for ORAC vs CAA-RBC units. Finally, the principal component analysis clearly pointed at the curly types from Fiumicino as bearing the highest antioxidant quality.
... Capacity. The DPPH free radical scavenging activity of the sample extract was evaluated by measuring the decrease in absorbance at 515 nm as previously reported [30]. The absorbance was measured against methanol using a Lenway 6705 UV-Vis spectrophotometer with 1 cm path length cuvettes. ...
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