K. Roininen, H. Virtanen, M. Lille, J. A. Kaukovirta-Norja, J. Buchert
VTT Technical Research Centre of Finland
 katariina.roininen@vtt.fi

Strawberry flavour compounds have been extensively studied. However a more complete understanding of the changes in sensory characteristics and aroma active compounds during strawberry processing is needed. The aim of the study was to investigate the effect of high-pressure thermal processing on freshness related flavour compounds of strawberry (Polka) puree.

Industrially frozen strawberries were thawed and homogenised. The strawberry puree was processed for 30 min at 0.1 or 800 MPa at 20, 50 and 74ºC.Volatile compounds of the samples were analysed by gas chromatography-mass spectrometry (GC-MS) using dynamic head space sampling. Sensory profile of similarly processed strawberries was performed by trained sensory panel of twelve assessors. The panel evaluated seven aroma characteristics (strawberry aroma, freshness, acid like, grass like, tea, chemical and off-odour) of samples. The sensory properties of samples were related to volatile compounds using multivariate regression analysis (PLS) in order to identify the freshness related volatiles that were changed due to the high-pressure thermal processing. Samples treated at low and medium temperatures either with or without high pressure were evaluated high in freshness, strawberry aroma, grass and acid like odour. Most of the esters and aldehydes were identified in these samples. Tea aroma and linalool were observed in samples that were treated at high pressure.

However, heat treatment tended to promote the formation of 3-methyl-2-pentanone, diacetyl, along with off-odour and chemical odour evaluated by sensory panel. These results together with previous results suggest that freshness of strawberry flavour is retained during high-pressure treatment at medium temperatures.