Monitoring two different drying methods of Kakadu plum puree by combining infrared and chemometrics analysis

ABSTRACT

The effect of two drying methods (oven and freeze drying) and the addition of maltodextrin to Kakadu plum puree samples (KP) (Terminalia ferdianandiana) were evaluated using mid (MIR) and near-infrared (NIR) spectroscopy. Dry powder samples were obtained using the oven and freeze-drying methods and seven levels of maltodextrin. Training (n = 32) and validation (n = 28) sets were developed for the prediction of moisture (M %), water activity (aw %), hydroxymethylfurfural (HMF) and vitamin C (VITC mg/100 g DM) based on NIR and MIR spectroscopy. Results from this study demonstrated the ability of spectroscopy combined with partial least squares (PLS) regression to monitor these parameters during drying. The standard error in cross validation (SECV) and the residual predictive deviation (RPD) values obtained were of 0.71% (RPD = 4.1) and 0.47% (RPD = 6.1) for M, 0.06% (RPD = 4.4) and 0.02% (RPD = 8.2) for aw, 0.73 (RPD = 3.3) and 0.72 (RPD = 3.3) for HMF, 465.7 mg 100 g DM (RPD = 3.0) and 289.3 mg 100 g DM (RPD = 4.8) for VITC, using MIR and NIR, respectively. The results from this study showed that MIR and NIR spectroscopies are capable of both measuring and monitoring the effect of drying and the addition of maltodextrin as a carrier to KP puree samples.

RESUMEN

Este estudio se propuso evaluar el efecto producido por dos métodos de secado (horno y liofilización) y por la adición de maltodextrina a muestras de puré de ciruela de Kakadu (KP) (Terminalia ferdianandiana) mediante espectroscopía de infrarrojo medio (MIR) e infrarrojo cercano (NIR). Con este objetivo se obtuvieron muestras de polvo seco utilizando los métodos de secado en horno y liofilización, además de adicionar siete niveles de maltodextrina. Así, se elaboraron conjuntos de práctica (n = 32) y validación (n = 28) para predecir la humedad (M %), la actividad del agua (aw %), el hidroximetil furfural (HMF) y la vitamina C (VITC mg/100 g MS) sobre la base de las espectroscopías NIR y MIR. Los resultados del estudio dieron cuenta de la capacidad de la espectroscopía, combinada con la regresión de mínimos cuadrados parciales (PLS), para monitorear estos parámetros durante el secado. El error estándar en la validación cruzada (SECV) y los valores de la desviación predictiva residual (RPD) obtenidos utilizando MIR y NIR fueron, respectivamente de: 0.71% (RPD = 4.1) y de 0.47% (RPD = 6.1) para M, 0.06% (RPD = 4.4) y 0.02% (RPD = 8.2) para aw, 0.73 (RPD = 3.3) y 0.72 (RPD = 3.3) para HMF, 465.7 mg 100 g de MS (RPD = 3.0) y 289.3 mg 100 g de MS (RPD = 4.8) para VITC. De esta manera, los resultados obtenidos permitieron constatar que las espectroscopías MIR y NIR son capaces de medir y de monitorear el efecto del secado y la adición de maltodextrina como portador de las muestras de puré de KP.

KEYWORDS:

• NIR
• MIR
• vitamin C
• hydroxymethyl furfural
• Kakadu plum

PALABRAS CLAVE:

• NIR
• MIR
• vitamina C
• hidroximetil furfural
• ciruela de Kakadu

Acknowledgments

The authors acknowledge the Traditional Owners of the lands on which the Terminalia ferdinandiana fruits were harvested respecting the knowledge and experience the Traditional Owners hold regarding the care, harvest and use of these plants.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Funding support from CRC for Developing Northern Australia Limited Project AT.2.1718031 – Improving the efficiency of Kakadu plum value chains to grow a robust and sustainable industry and the Australian Research Council (ARC) Industrial Transformation Training Centre (ITTC) for Uniquely Australian Foods (Grant number: IC180100045);Cooperative Research Centre for Developing Northern Australia [AT.2.1718031];ARC [IC180100045].