The quality of sliced carrots affected by modified polyethylene foil and storage temperatures

The aim of this study was to examine the influence of different additive contents for oxygen absorption (5, 10 and 15%) in low-density polyethylene (PELD) plastic foils and storage temperatures (4 and 28 °C) on the quality and shelf-life of sliced carrots during storage. Quality and storage-life of packaged carrots slices were determined by observing changes of mass, total carotenoide pigments, microbial counts (mesophilic aerobic bacteria, enterobacteria, sulphite-reducing clostridia, yeast and moulds), sensory quality and texture by the use of penetrometer. The PELD foils modified with 10 and 15% of oxygen absorber (O2, CO2 and N2 permeability at 4 °C of around 700 ml m-2d-1atm-1) were the most suitable for the storage and prevention of deterioration of minimally processed carrots. Findings indicated that in these foils the best quality and shelf-life of carrot were maintained by 6 days of storage at 4 °C, without significant changes in parameters studied. The absorber for oxygen added to the foil had no influence on the permeability to CO2, O2and N2. The permeability of foils, which were used for carrot packaging increased by the increase of storage temperature to 28 °C and decreased by decreasing the temperature to 4 °C, and was not significantly affected by the additive content either. In the same time the diffusion constants of unused and used PELD foils for carrot packaging at 4 °C and 28 °C changed according to the change of film permeability during storage at those temperatures

Effect of processing on the drying kinetics and functional value of dried apricot

Apricots can be considered as a good source of phenolic compounds, which are beneficial for human health. Microwaves may be an alternative to the conventional sun or hot air drying techniques used to obtain dried apricot. Nevertheless, their impact on the functional compounds must be taken into account if they are to be recommended as an attractive drying option. This work compares the drying kinetics and the change in the organic acids, phenolic compounds and antioxidant activity of dried apricot when using hot air drying and microwave energy. Empirical (linear and Page) equations can be used to model the drying kinetics in air, combined air-microwave and microwave processes. From the obtained results, it can be concluded that the industrial processing of dried apricots may be improved by using microwave energy, as the drying time is considerably reduced, and the obtained fruit had a higher phenolic content, particularly of chlorogenic acid, catequin and epicatequin. Nevertheless, as the contribution of these phenols to antioxidant capacity was not significant, microwave dried samples maintained the same antioxidant capacity as the air-dried ones. When sulphite is added previous to the drying processes, care should be taken with the total phenols and the antioxidant capacity quantified as it may interfere with the results depending on the methodology used. © 2011 Elsevier Ltd.Igual Ramo, M.; García Martínez, EM.; Martín-Esparza, M.; Martínez Navarrete, N. (2012). Effect of processing on the drying kinetics and functional value of dried apricot. Food Research International. 47(2):284-290. doi:10.1016/j.foodres.2011.07.019S28429047

The effect of ripening and storage on peach pectin and gel strength of related jams

Peaches were harvested in three stages of ripeness (threshold-mature - I, firm-ripe - II and ripe - III). Firm-ripe (II) peaches were stored for 9 days at 4 and 22 C. The amount of water-soluble, oxalate-soluble and alkali-soluble pectin were extracted and quantitatively determined as galacturonic acid, neutral sugars were determined as glucose. Jams were made with all peach samples as well as gels from extracted fractions. Gel strength of jams and gels was measured.  Dry matter, sugar composition (amount of sucrose and reducing sugars) and pH value were determined and very little change was found during the ripening period and storage, too.  Alkali-soluble fraction was more abounding than water-soluble fraction. The oxalate-soluble pectic fraction was found to be a minor fraction in all peach samples. The amount of total pectin and the amount of alkali-soluble pectin fraction dropped markedly after the 1st stage of ripening, after the 2 nd day of storage at 22 C and slightly after the 6th day of storage at 4 C. The level of alkali-soluble pectin in total pectin was inversely proportional to the level of water-soluble pectic fraction, and the level of oxalate-soluble pectic fraction in total pectin content was fairly constant during the ripening and storage. Gel strength of jams and gels correlated very well with changes of the amount of alkali-soluble pectic fraction.  The extracted alkali-soluble pectic fraction was capable of forming an acidic gel. Extracted oxalate-soluble pectic fraction forms a gel in the presence of calcium and solid matter more than 77%.  It seems that the amount of alkali-soluble pectic fraction in peaches is responsible in producing peach jams according to gel strength

Effect of drying conditions on indole glucosinolate level in broccoli

Broccoli is interesting as raw vegetable for domestic use and as well as dehydrated powder due to content of numerous biologically active compounds — phytochemicals. We examined the influence of blanching and drying air temperature and velocity on glucosinolate composition and content under conditions which are usually applied in industrial processing of broccoli. Broccoli blanching prior to drying caused a significant decrease in the glucosinolate content, which additionally decreased during the drying process. Drying at 50 °C and 60 °C with air velocity of 2.25 m s−1 was the most favourable in most of the cases

Sources, stability, encapsulation and application of natural pigments in foods

In recent years, the replacement of synthetic colorants with natural ones has attracted increasing consumers’ and market interest. Natural colorants include different groups of pigments, many of which possess also pronounced biological potential. This review addresses the main issues related to the use of natural pigments in foods, starting from the sources available in nature, their chemical properties, stabilization processes, and applications in real foods, as discussed in the scientific literature reported in the main databases relevant to this topic (Scopus, Web of Science, PubMed, ScienceDirect, and Google Scholar). Notably, several natural pigments are available to cover different needs in terms of hues and intensities, and whose use is permitted in foods by the main regulatory agencies. However, their use is still frequently limited by their higher price and lower stability than synthetic counterparts. This review discusses in detail the main sources for natural pigments, focusing on the recent trends towards those more economically favorable, such as microbial sources and agro-industrial residues. It also examines the most suitable stabilization systems to protect the highly reactive and unstable molecules of natural pigments from negative physical and chemical changes, as well as to minimize the interactions with food systems