4 Effects of ascorbic acid and light on reactions in fresh-cut apples……………….

146 Pages·2017·5.24 MB·English

Freie Universität Bozen
unibz
Libera Università di Balzano
Università Liedia de Bulsan

Faculty of Science and Technology

PhD in Mountain Environment and
Agriculture
(29th cycle)

PhD Dissertation

REACTION CALORIMETRY AS A TOOL FOR
STUDYING THE QUALITY OF FRESH-CUT
FRUITS AND THE EFFICACY OF VARIOUS
PRESERVATION TREATMENTS

PhD Coordinator: Prof. Tonon Giustino
Supervisor: Prof. Matteo Scampicchio
Co-supervisor: Prof. Aberto Schiraldi
Co-supervisor: Prof.ssa Tanja Mimmo

Candidate: Hasan S. M. Kamrul

Year 2017
Freie Universität Bozen
unibz
Libera Università di Balzano
Università Liedia de Bulsan

Faculty of Science and Technology

PhD in Mountain Environment and
Agriculture
(29th cycle)

PhD Dissertation

REACTION CALORIMETRY AS A TOOL FOR
STUDYING THE QUALITY OF FRESH-CUT
FRUITS AND THE EFFICACY OF VARIOUS
PRESERVATION TREATMENTS

PhD Coordinator: Prof. Tonon Giustino
Supervisor: Prof. Matteo Scampicchio
Co-supervisor: Prof. Aberto Schiraldi
Co-supervisor: Prof.ssa Tanja Mimmo

Candidate: Hasan S. M. Kamrul

Year 2017
Table of Contents Page
Table of contents............................................................................................................ i
Summary ....................................................................................................................... iv
Riassunto ...................................................................................................................... v
Zusammenfassung ...................................................................................................... vi
Chapter I ......................................................................................................................... 1
1 State of the art ......................................................................................................... 1
1.1 Introduction ........................................................................................................ 2
1.2 Calorimetric process analyser ............................................................................ 4
1.2.1 A reaction calorimeter .................................................................................. 6
1.2.2 A microcalorimeter ....................................................................................... 8
1.3 Application of different innovative treatments ................................................... 10
1.3.1 UV-C light .................................................................................................. 10
1.3.2 Pulsed light ................................................................................................ 13
1.3.3 Emulsion technology ................................................................................. 15
1.4 Traditional dipping treatment ............................................................................ 17
1.5 Research objectives ......................................................................................... 18
1.6 Research hypotheses ...................................................................................... 19
1.7 References ....................................................................................................... 20
Chapter II ...................................................................................................................... 28
2 Nanoemulsion as nano-carrier for fresh-cut fruits: a review ............................ 28
2.1 Introduction ...................................................................................................... 30
2.2 Potential functional compounds to be carried by nanoemulsion systems ........ 34
2.2.1 Antimicrobial agents .................................................................................. 34
2.2.2 Antioxidant agents/Anti-browning agents................................................... 38
2.2.3 Texture enhancers ..................................................................................... 39
2.3 Nanoemulsion formulation ............................................................................... 41
2.4 Nanoemulsion characterization ........................................................................ 46
2.5 Conclusion ....................................................................................................... 52
2.6 References ....................................................................................................... 54
Chapter III ..................................................................................................................... 65
3 Food and Ascorbic Scavengers of Hydrogen Peroxide .................................... 65
3.1 Introduction ...................................................................................................... 67
i
3.2 Materials and methods ..................................................................................... 68
3.2.1 Materials .................................................................................................... 68
3.2.2 Reaction calorimetry apparatus . ............................................................... 69
3.2.3 Optimized procedure ................................................................................. 70
3.3 Results ............................................................................................................. 70
3.3.1 Solutions of Ascorbic Acid ......................................................................... 70
3.3.2 Scavenging Properties of Some Food Products. ....................................... 72
3.4 Discussion ........................................................................................................ 74
3.5 Conclusions...................................................................................................... 84
3.6 References ....................................................................................................... 86
Chapter IV .................................................................................................................... 88
4 Effects of Ascorbic Acid and Light on Reactions in Fresh-cut Apples by
Microcalorimetry ......................................................................................................... 88
4.1 Introduction ...................................................................................................... 90
4.2 Methods ........................................................................................................... 91
4.2.1 Fresh cut apple samples............................................................................ 91
4.2.2 Dipping treatments .................................................................................... 92
4.2.3 Pulsed light treatments .............................................................................. 92
4.2.4 UV-C treatments ........................................................................................ 92
4.2.5 Isothermal microcalorimetry ....................................................................... 93
4.2.6 Oxygen measurement ............................................................................... 93
4.3 Results and Discussions .................................................................................. 94
4.3.1 Calorimetric signal ..................................................................................... 94
4.3.2 Oxygen consumption ................................................................................. 96
4.3.3 Fitting of the experimental points ............................................................... 97
4.3.4 Effect of Ascorbic acid ............................................................................... 98
4.3.5 Application of light treatments .................................................................. 100
4.4 Conclusion ..................................................................................................... 102
4.5 Acknowledgments .......................................................................................... 102
4.6 References ..................................................................................................... 103
Chapter V ................................................................................................................... 106
5 Free-radical Scavenging Capacity using Fenton reaction by Reaction
Calorimetry ................................................................................................................ 106
5.1 Introduction .................................................................................................... 108
5.2 Materials and methods ................................................................................... 109
ii
5.2.1 Materials .................................................................................................. 109
5.2.2 Reaction calorimetry apparatus ............................................................... 110
5.2.3 Optimized procedure ............................................................................... 111
5.3 Results and discussions ................................................................................. 111
5.3.1 Reaction calorimetry of the Fenton reaction ............................................ 111
5.3.2 pH effect on the rate of the Fenton Reaction ........................................... 117
5.3.3 Iron (Fe2+) effect on the rate of the Fenton Reaction .............................. 119
5.3.4 Hydrogen peroxide (H O ) effect on the rate of the Fenton Reaction ...... 120
2 2
5.3.5 Free-radical scavenging activity of antioxidant compounds ..................... 121
5.3.6 Free-radical scavenging capacity of food products .................................. 123
5.4 Conclusion ..................................................................................................... 125
5.5 References ..................................................................................................... 127
Chapter VI .................................................................................................................. 131
6 Conclusions and Future Prospects .................................................................. 131
6.1 General conclusion ........................................................................................ 132
6.2 Future prospects ............................................................................................ 135
Acknowledgement..................................................................................................... 136

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Summary
This research was aimed to investigate the quality changes of fresh-cut fruits and the
efficacy of various preservation treatments by calorimetric process analyser. First, the
study was focus on the development of a novel method based on reaction calorimetry
for monitoring the oxidation reaction in foods. The instrument measures the heat flow
signal (W) released during the reaction. Such heat flow as well as its integral yields the
heat (J) of the reaction. The overall heat was used as index to express the antioxidant
capacity of the food samples. The oxidation reaction was investigated between food
containing antioxidants and an oxidant reagent (i.e. hydrogen peroxide). The results
suggested to use of reaction calorimetry to investigate the antioxidant capacity of fruit
juices, fruit puree, tea, coffee and alcoholic beverages, like wines without time
consuming sample pre-treatment protocol. The reliability of the approach is assessed
through the study of the reaction between hydrogen peroxide and ascorbic acid at
different concentrations and pH at 250C. The second aim was focused to evaluate the
efficiency of traditional and innovative preservative treatments on fresh-cut fruits using
novel calorimetric approach for monitoring the reaction. Fresh-cut apples (Malus
domestica cv. Golden Delicious) were subjected to different stabilization treatments,
such as dipping with ascorbic acid solutions (traditional treatment), exposure to UV-C
and pulsed light (innovative treatments). The rate of reaction of treated fresh-cut apples
was investigated with microcalorimetry. The apple slices treated with ascorbic acid,
pulsed light or UV-C treatments showed decrease in the heat flow than control, which
confirm the reduction of fruit reaction. The heat flow signal was proportional to the
concentration of ascorbic acid or pulsed light dose used, but was not linearly
proportional to the fluence of the UV-C treatment. The findings of this study suggest
that innovative treatments based on the irradiance of light were able to preserve and
enhance the stability of fresh-cut apples, and also suggest the suitability of calorimetry
to determine the stability of fresh-cut fruits.
Moreover, to accelerate the oxidation reaction in foods, reaction calorimetry method
was extended using Fenton type reaction for its industrial application. The method was
performed on same samples like previous application of this method, and the results
were promising, which made ten times faster of the oxidation of antioxidant compounds
(i.e. ascorbic acid) and food samples.
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Riassunto
Questa ricerca ha avuto lo scopo di indagare i cambiamenti qualitativi della frutta fresca
tagliata e l'efficacia di vari trattamenti di conservazione mediante l’analisi calorimetrica.
Il primo obiettivo della ricerca consisteva nello sviluppo di un nuovo metodo basato
sulla reazione calorimetrica per il monitoraggio della reazione di ossidazione negli
alimenti. Lo strumento misura il segnale del flusso di calore (W) prodotto durante la
reazione, cosi come il suo integrale, ossia il calore (J) emesso durante la reazione. Il
calore totale è stato usato come indice per esprimere la capacità antiossidante dei vari
campioni di alimenti. La reazione di ossidazione è stata studiata negli alimenti
contenenti antiossidanti a cui sono stati aggiunti agenti con azione ossidante (ad
esempio l’acqua ossigenata). I risultati suggeriscono di utilizzare la reazione
calorimetrica per indagare la capacità antiossidante dei succhi di frutta, purea di frutta,
tè, caffè e bevande alcoliche come il vino, senza la necessità di avere un protocollo di
pre-trattamento del campione. L’affidabilità di questo approccio è stata valutata
mediante lo studio della reazione tra l’acqua ossigenata e l’acido ascorbico a varie
concentrazioni e diversi pH alla temperatura di 25°C. Il secondo obiettivo è stato
orientato a valutare l’efficienza dei trattamenti di conservazione tradizionali ed innovativi
sulla frutta fresca tagliata usando un approccio nuovo come quello della calorimetria
per il monitoraggio della reazione. Le mele tagliate (Malus domestica cv. Golden
Delicious) sono state soggette a diversi trattamenti di stabilizzazione, quali l’immersione
nell’acido ascorbico (trattamento tradizionale), e l’esposizione ai raggi UV-C e la luce
pulsata (trattamento innovativo). La velocità di reazione della mela tagliata e trattata è
stata misurata con la microcalorimentria. Le fette di mela trattate con acido ascorbico,
UV-C o luce pulsata hanno mostrato un flusso di calore minore rispetto al controllo, ciò
conferma la riduzione della reazione della frutta. Il segnale di flusso di calore è stato
proporzionale alla concentrazione dell’acido ascorbico e alla luce pulsata ma non in
modo lineare rispetto al trattamento con UV-C. I risultati di questa ricerca suggeriscono
che l’uso dei trattamenti innovativi basati sull’irradiazione con luce sono in grado di
preservare la stabilità della mela fresca tagliata; inoltre suggeriscono l’adeguatezza
nell’uso della calorimetria nella determinazione della stabilità della frutta fresca tagliata.
Inoltre, per accelerare la reazione d’ossidazione negli alimenti, la reazione calorimetrica
è stata applicata alla reazione di “Fenton”, usata nell’industria. Il metodo è stato
eseguito applicando il metodo descritto precedentemente ed i risultati sono stati
incoraggianti, in quanto la reazione di ossidazione dei composti antiossidanti (come
l’acido ascorbico) e dei campioni alimentari è stata 10 volte più veloce.
v
Zusammenfassung
Das Ziel dieser Studie war die kalorimetrische Untersuchung von
Qualitätsveränderungen von frischen geschnittenen Früchten und die Wirksamkeit von
verschiedener Konservierungsbehandlungen.
Die erste Zielsetzung dieser Studie war die Entwicklung einer neuartigen
reaktionskalorimetrischen Methode für die Überwachung die Oxidationsreaktion in
Lebensmitteln. Der Kalorimeter misst dabei das Signal des Wärmestroms (W), der
während der Reaktion befreit wird. Das Instrument nicht nur den Wärmestrom, aber
auch dessen Integral, die Reaktionswärme (J). Die Gesamtwärme wurde als Index für
das antioxidierende Fähigkeit der Lebensmittelproben herangezogen. Die
Oxidationsreaktion wurde zwischen Lebensmitteln, die Antioxidantien enthaltenen und
einem Oxidierungsmittel, wie z.B. Wasserstoffperoxid untergesucht. Die Ergebnisse
deuten auf die Anwendung der Reaktionskalorimetrie für die Untersuchung der
antioxidierenden Fähigkeit von Fruchtsäften, Fruchtmus, Tee, Kaffee und alkoholische
Getränke wie Wein, ohne zeitintensivem Vorbehandlungsprotokoll. Die Verlässlichkeit
dieser Herangehensweise wurde geprüft, indem die Reaktion von Wasserstoffperoxid
mit Ascorbinsäure in verschiedenen Konzentrationen und bei unterschiedlichem pH, bei
25°C.
Die zweite Zielsetzung war neuartige und weiterentwickelte
Konservierungsbehandlungen mit Kalorimetrie zu bewerten. Frisch geschnittene Äpfel
(Malus domestica cv. Golden Delicious) wurden an unterschiedlichen
Stabilisierungsbehandlungen untergezogen, wie Eintauchen in Ascorbinsäure-Lösung
(traditionelle Behandlung), sowie Belichtung mit UV-C und gepulstes Licht (innovative
Behandlungen). Die Reaktionsrate den Apfelzuschnitten wurde mit Mikrokalorimetrie
untergesucht. Apfelzuschnitte, behandelt mit UV-C, gepulstem Licht und Ascorbinsäure,
zeigen eine Abnahme an Wärmestrom im Unterschied zur Negativkontrolle. Dies
bestätigt die Reduktion der Obstes Reaktion. Der Wärmestrom war proportional zur
Konzentration der Ascorbinsäure und den Dosis des gepulsten Lichtes. Der
Wärmestrom war jedoch nicht linear proportional zur Einwirkung mit UV-C Licht. Die
Ergebnisse dieser Studie zeigen, dass innovative Obstbehandlungen auf der Grundlage
von Lichtbestrahlung die Konservierung und Stabilität von Schnittobst erhöhen.
Außerdem konnte die Eignung von kalorimetrischen Methoden zur Untersuchung der
Stabilität von frischem Schnittobst bestätigt werden.
vi
Um die Oxidierungsreaktion in Lebensmitteln zu beschleunigen, wurde die
reaktionskalorimetrische Methode um die Fenton-Reaktion für dessen industrielle
Anwendung erweitert. Die Methode wurde an dieselben Proben wie die vorherige
Methode angewandt. Die Ergebnisse waren vielversprechend, da die Oxidierung von
Antioxidantien (z.B. Ascorbinsäure) und Lebensmittelproben um das Zehnfache
beschleunigt wurde.

vii
Organization and Structure of the thesis

Chapter 1 discusses the general information of fresh-cut fruits, production and
significance together with the review of their quality evaluation methods and processing
treatments. It also focuses on the formulation of research objectives and hypotheses.
Chapter 2 presents a review on nanoemulsion as nano-carrier for fresh-cut fruits:
formulation, characterization and its application. Chapter 3 discusses about the
development and application of novel method based on reaction calorimetry to
investigate the scavenging capacity of foods. The method was validated with different
concentrations of ascorbic acid and pH. This method was also next applied in chapter 4
to investigate the effects of ascorbic acid and light on reaction in fresh-cut apples.
Chapter 5 discusses the extended application of reaction calorimetry method via Fenton
reaction to monitor the reaction of foods. Finally, chapter 6 summarized the general
conclusions and future prospects of this work.

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