Impregnation Techniques for Aroma Enrichment of Apples: a Preliminary Study

Food industry often needs flavour enriched food products to be employed as ingredients of more complex preparations. At the best of our knowledge there are not applications concerning with the production of minimally processed food items enriched with aromas. This research aims to enrich apples with an artificial green apple aroma, applying different techniques; vacuum impregnation (VI), ultrasound technology (USI) and the combination of these two techniques (VUSI) were tested and compared with atmospheric pressure impregnation (AI). An isotonic solution of fructose, containing ascorbic acid and green apple artificial aroma was used for the impregnation of regular and uniform sticks of apple. Different durations of impregnation (2.5, 5.0 and 7.5 minutes) were tested and the impregnation kinetics of the main components of artificial aroma were recorded. Significant differences between treatments were detected: VI and VUSI gave the highest aroma enrichment at 5 minutes of treatment. Different impregnation kinetics were recorded for alcohols and esters: the first tended to increase even after 7.5 minutes of treatments, the others components instead grown until 5 minutes and then decreased, mainly when ultrasounds were applied (US and VUSI). Some possible causes of such results were hypothesized, but the need of further studies is, also suggested in order to clarify the mechanisms involved

Impregnation Techniques for Aroma Enrichment of Apple Sticks: A Preliminary Study

The food industry often utilizes flavor-enriched, semifinished food products as ingredients in more complex preparations. To the best of our knowledge, there are no methods to produce minimally processed food items to which flavorings have been added. In this investigation, apple sticks were enriched with a green apple aroma using different techniques. In particular, vacuum impregnation (VI), ultrasound technology (USI), and the combination of these two techniques (VUSI) were compared with atmospheric pressure impregnation (AI). An isotonic solution of fructose containing ascorbic acid and green apple flavoring was used for impregnation of apple sticks. Different treatment times (2.5, 5.0, and 12.5 min) were investigated, and the relative amount of the major compounds of impregnation flavoring was recorded. Significant differences between treatments were detected: VI and VUSI gave the highest aroma enrichment at 5.0 min of treatment. Different impregnation behaviors were recorded for alcohols and esters: the former increased even after 5.0 min of treatment, and the other components increased until 5.0 min and then decreased, mainly when ultrasound was applied (USI and VUSI). Some possible explanations of these results are proposed, although additional studies are needed to explain the mechanisms involved

L\u2019impregnazione sotto vuoto come tecnica di funzionalizzazione della frutta: studio sulle mele cotogne.

Gli alimenti funzionali sono prodotti capaci di fornire un beneficio salutistico superiore a quello dovuto ai nutrienti tradizionali che contengono. Ad ora non esiste una definizione univoca di alimenti funzionali, ma tra quelle impiegate in passato e sicuramente comprese in questa categoria si possono citare gli alimenti arricchiti e quelli fortificati. I primi sono addizionati di nutrienti naturalmente presenti nel prodotto stesso, gli alimenti arricchiti, invece, sono addizionati di componenti non presenti nell\u2019alimento originario 1-2. L\u2019impregnazione sottovuoto \ue8 una tecnologia ampiamente impiegata nella produzione di alimenti arricchiti e fortificati. Tale tecnica consiste nell\u2019immersione dell\u2019alimento in una soluzione contenente il componente del quale lo si vuole arricchire e, grazie all\u2019applicazione del vuoto, viene facilitato l\u2019ingresso della soluzione all\u2019interno della matrice alimentare. Due sono i meccanismi coinvolti nell\u2019impregnazione sottovuoto, la deformazione dei pori dovuta all\u2019applicazione del vuoto ed il rilassamento che si instaura a partire dal momento della rottura del vuoto. L\u2019ingresso della soluzione all\u2019interno della matrice alimentare \ue8 dovuto anche al meccanismo idrodinamico, generato dal differenziale di pressione osmotica esistente tra l\u2019interno e l\u2019esterno del prodotto. L\u2019efficienza dell\u2019impregnazione \ue8 influenzata da numerose variabili, legate sia alle propriet\ue0 della soluzione, quali viscosit\ue0, densit\ue0, tensione superficiale, sia alla microstruttura del prodotto, come porosit\ue0 e deformabilit\ue0, ed infine alle variabili di processo quali la pressione di vuoto, il tempo di applicazione del vuoto e quello di rilassamento. La mela cotogna (Cidonia oblonga Miller), grazie all\u2019elevato contenuto di composti fenolici, presenta gi\ue0 un valore salutistico elevato, ma \ue8 scarsamente consumata fresca a causa della significativa astringenza legata all\u2019elevato contenuto di tannini. In questo studio preliminare sono state valutate le propriet\ue0 di impregnazione della mela cotogna, con soluzioni di glucosio, con la finalit\ue0 di ridurre la percezione dell\u2019astringenza, incrementandone l\u2019impiego fresco, oggi poco rilevante, in prodotti ready to eat, a base di frutta. La stessa metodica pu\uf2 essere utilizzata impiegando sciroppi di glucosio arricchiti di sostanze, a polarit\ue0 simile, dotate di propriet\ue0 nutraceutiche, come calcio e zinco3, allo scopo di associare il miglioramento delle caratteristiche organolettiche del prodotto all\u2019arricchimento in sostanze fisiologicamente attive. Bibliografia 1 Gras M.L. et al., Journal of Food Engineering 2003, 56, 279-284. 2 Siro, J. et al., Appetite 2008, 51, 456-467. 3 Xie J. e Zhao Y., International Journal of Food Sciences and Nutrition 2003, 54, 387-398

Sorption Behavior of citric pectin films with glycerol and olive oil

The effect of glycerol and olive oil on water sorption isotherms of orange (FOP) and grapefruit (FGP) peel pectin films was studied. Additives decreased the equilibrium moisture content (X) and the extent of the observed hysteresis. Abrupt changes in the adsorption isotherms of the films were noted, and were very well correlated to one of the maxima of the second derivative of X as function of aw. Converted adsorption data for GAB regression (aw/X) generated curves with a sharp peak, linked to the isotherms inflection points. aw/X vs aw diagrams were valuable to identify order-to-disorder transitions in pectin films. Glycerol concentration reduced the critical water activity in FGP. GAB model described adsorption isotherms above the transition (R2 > 0.932), and Halsey model exhibited a better fit (R2 > 0.984). Desorption phenomena was better described by Peleg model (R2 > 0.959)

Effects of power ultrasound on immersion freezing parameters of potatoes

Ultrasound has attracted great interest in recent years and its application in food freezing has shown promising advantages. In the present study the application of ultrasound during immersion freezing of potato cubes was studied and particular attention was given to the effects on supercooling process. Ultrasound, produced through a 35 kHz sonotrode, was applied when the temperature in the geometrical center of potato sample was in the range from - 0.1 to - 3.0 C. Several freezing parameters, as nucleation temperature and time, supercooling, initial freezing temperature, transition phase and global freezing duration, were evaluated and discussed. A significant anticipation of nucleation was detected when the ultrasound application temperature was lower than - 0.1 C; moreover it was found a linear correlation between ultrasound irradiation temperature and supercooling reached in potato samples; finally a reduction in freezing time was recorded when ultrasound was applied at - 2.0 C. Industrial relevance Ultrasound has acquired relevance in several industrial sectors, including food science and technology. In the present investigation power ultrasound has been studied in assisting and accelerating immersion freezing of potato cubes, obtaining promising results. In fact it was found that ultrasound was able to induce nucleation in the centre of potato cubes, interrupting the supercooling process. Moreover, under particular operative conditions, the freezing time of ultrasound-assisted potato cubes was significantly reduced with respect to non-irradiated samples. The results achieved demonstrate that the application of power ultrasound during immersion freezing has a great potential in the control of the freezing process. In particular the possibility of reduction of the freezing time and costs, as well as the influence of ultrasound on quality, stability and sensory properties of frozen food have a crucial importance to food industry and have to be widely investigated