Changes in flavour and texture during the ripening of strawberries

The amount of total volatile compounds, total acidity, total sugar content (degrees Brix) and fruit firmness were used to characterize the degree of ripeness of three strawberry varieties (Carezza, Darselect and Marmolada). A novel concept using solid phase microextraction (SPME) and measurement of total volatile compounds to distinguish between various stages of strawberry ripeness was applied. The carboxene/polydimethylsiloxane SPME fibre was found to be best suited to differentiate between the stages of ripeness. The amount of total volatile compounds rapidly increased near to maturity (between the three-quarters red stage and the dark-red stage). Most of the volatile compounds identified were esters, followed by aldehydes, and alcohols. The most abundant volatile compounds were propyl butanoate, 3-phenyl-1-propanol, butyl butanoate, isobutyl butanoate, 3-methyl butyl butanoate and isopropyl hexanoate. The concentration of green aroma components such as hexanal, trans-2-hexenol and cis-3-hexenyl acetate progressively decreased during the maturation process until they became minor components in mature strawberrie

Influence of storage on the volatile profile, mechanical, optical properties and antioxidant activity of strawberry spreads made with isomaltulose

[EN] This work represents the final step of a series of studies on the formulation of strawberry products with partial replacement of sucrose by healthier sugars such as fructose and isomaltulose. Previously, quality parameters of the formulated products such as colour, texture, rheology, aromatic profile and sensory evaluation were assessed. As a final step, in the present work, the volatile profile evolution of a strawberry spread-product during 90 days of storage at room temperature (20 °C), and its relation with some physicochemical properties (aw, pH, texture and colour) and antioxidant activity as well as anthocyanin content were studied. Most of the volatile compounds modified their concentration during storage; some of them totally disappeared but 13 new compounds were formed: (methyl-2-methyl butyrate, E-2-butenal, 2-butenal-2-methyl, 2-buten-1-ol, 2-penten-1-ol, 2-etil-1-hexanol, 6-methyl-5-hepten-2-one, acetic acid, propanoic-2-methyl acid, butyric acid and butyric-2-methyl acid). Storage led to a dark pink colour and an increase in consistency and adhesiveness while the antioxidant activity considerably increased (from 18±2% to 94±2% DPPH inhibition). Levels of citric acid and pectin influenced colour, texture and antioxidant activity as well as retention and formation of aromatic compounds, especially in fructose isomaltulose products. Correlations via a PLS were found between the aromatic profile of the products after storage and some of their quality parameters such as texture, colour and antioxidant content. Future research might involve correlation and identification of specific volatiles with different quality parameters.Authors would like to thank Ministry of Science and Education's General directorate of Research (AGL2008-01745/ALI) for the financial support given to this investigation.Peinado Pardo, I.; Rosa Barbosa, EM.; Heredia Gutiérrez, AB.; Escriche Roberto, MI.; Andrés Grau, AM. (2016). Influence of storage on the volatile profile, mechanical, optical properties and antioxidant activity of strawberry spreads made with isomaltulose. Food Bioscience. 14:10-20. https://doi.org/10.1016/j.fbio.2016.02.001S10201

Effect of Maturity on Phenolics (Phenolic Acids and Flavonoids) Profile of Strawberry Cultivars and Mulberry Species from Pakistan

In this study, we investigated how the extent of ripeness affects the yield of extract, total phenolics, total flavonoids, individual flavonols and phenolic acids in strawberry and mulberry cultivars from Pakistan. In strawberry, the yield of extract (%), total phenolics (TPC) and total flavonoids (TFC) ranged from 8.5–53.3%, 491–1884 mg gallic acid equivalents (GAE)/100 g DW and 83–327 mg catechin equivalents (CE)/100 g DW, respectively. For the different species of mulberry the yield of extract (%), total phenolics and total flavonoids of 6.9–54.0%, 201–2287 mg GAE/100 g DW and 110–1021 mg CE/100 g DW, respectively, varied significantly as fruit maturity progressed. The amounts of individual flavonols and phenolic acid in selected berry fruits were analyzed by RP-HPLC. Among the flavonols, the content of myricetin was found to be high in Morus alba (88 mg/100 g DW), the amount of quercetin as high in Morus laevigata (145 mg/100 g DW) while kaempferol was highest in the Korona strawberry (98 mg/100 g DW) at fully ripened stage. Of the six phenolic acids detected, p-hydroxybenzoic and p-coumaric acid were the major compounds in the strawberry. M. laevigata and M. nigra contained p-coumaric acid and vanillic acid while M. macroura and M. alba contained p-hydroxy-benzoic acid and chlorogenic acid as the major phenolic acids. Overall, a trend to an increase in the percentage of extraction yield, TPC, TFC, flavonols and phenolic acids was observed as maturity progressed from un-ripened to fully-ripened stages

A new concept for the measurement of total volatile compounds of food

The aim of our work was to develop a rapid and reliable method for the evaluation of the total volatile fraction of fruits (strawberries, raspberries, tomatoes and apples). Our method consists of trapping the volatile compounds of fruits on a solid-phase microextraction (SPME) fibre and determining the total amount of the adsorbed substances after desorption in a GC system, without performing any separation. The patterns obtained by using several types of SPME fibre permitted us to differentiate between the total volatile compounds present in the sample depending upon their chemical nature. Using strawberries as a model, we could show that our method: (1) leads to easily reproducible results; (2) allows differentiation between six varieties in a way which is consistent with an hedonic evaluation of these varieties; (3) shows the variation in total volatile compounds between individual fruits. The technique is rapid, practical, cheap, and promising for an objective evaluation of the volatile fraction of fruits