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Potato and sweet potato are two among the most important commodities worldwide due to their significant role in human diet and food security. As highly demanded crops, rapid quality monitoring methods prior to marketing, processing, and other post-harvest activities are the major concerns of consumers and food processors. The non-destructive techniques in terms of imaging and spectroscopy have become effective analytical tools in evaluating the quality of various horticultural and food products including potatoes and sweet potatoes. Hence, this paper reports the current knowledge on the recent applications of imaging and spectroscopy for inspecting the quality and safety of raw potato and sweet potato tubers. In this comprehensive review, the conventional quality evaluation (internal and external) are discussed, followed by description of imaging and spectroscopy as non-destructive techniques and, the summary of the recent successful implementations of these tools in relation to quality evaluation. The basic and fundamental components of the technique, measurement methods and data analysis applied, advantages, and challenges are also critically reviewed.

The shelf life of banana is very much dependent on the preparation method, packaging method, and storage temperature. Thus, this work is directed to investigate the effect of banana preparation (peeled and unpeeled), packaging method (vacuum packed and non-vacuum packed), and storage temperature (25 and 9 °C) on extending the shelf life of Saba banana. Peeled and unpeeled; and vacuum packed and non-vacuum packed banana was kept at different storage temperatures for 28 days. The shelf life of banana was investigated in terms of texture, color changes, and moisture content every 7 days. It was found that vacuum packed banana samples kept at 9 °C exhibited non-significant changes in firmness, and minimal changes in moisture content and color compared to non-vacuum packed banana kept at 25 °C, proving that vacuum packaging and low storage temperature are promising to extend the shelf life of banana. The unpeeled banana was also demonstrated to exhibit longer shelf life compared to peeled banana because the skin is able to preserve the moisture content inside the banana and prevent the banana to become dried and spoilt over time.

In this study, we investigated the effects of different storage temperatures on the quality and shelf-life of Malaysian sweet potatoes in terms of moisture content (MC), soluble solids content (SSC), colour values (L*, a*, b*) and textural properties. Samples from the three locally-produced sweet potato varieties in Malaysia namely: Keledek Anggun 3 (V1), Keledek Jingga (V2), and Keledek Kuning (V3) were purchased and stored at 5 °C, 15 °C and 30 °C for a period of 21 d with a relative humidity (RH) range of 80–90%, 70–80% and 50–60%, respectively. A multiple correlation analysis was employed in establishing the relationships between the changes in all the quality parameters (QP). The results showed that the QP of sweet potatoes in all varieties were significantly affected (P 0.60; *P

Optical imaging techniques have gained wide attention for quality detection of agricultural and food products. In this work, the non-destructive ability of the laser-light backscattering imaging technique (LLBI) for monitoring and classifying the quality changes of sweet potatoes under different storage conditions was investigated. Freshly-harvested sweet potato root samples were stored at 5 °C, 15 °C and 30 °C for a period of 21 d with 120 samples in each storage group. Laser diode emitting light at 658 nm wavelength along with the camera system was employed to capture the backscattered light from the subjected samples. The acquired backscattering images were then pre-processed and segmented, and the intended backscattering parameters (BP) were extracted. Quality parameters (QP) such as moisture content (MC), soluble solids content (SSC), texture and color properties (L*, a*, b*) were measured using the conventional methods as standard reference data. Multivariate analysis in terms of partial least squares regression (PLSR), principal component analysis (PCA) and linear discriminant analysis (LDA) was carried out to correlate and classify the sweet potatoes based on the BP. Results showed that storage had a significant effect both in the BP and QP of sweet potatoes as well as in the interaction between the BP and the treatments (day and temperature) applied. Among all the QP, SSC gave the most promising results (R = 0.56-0.66; RMSE = 0.76–1.10) across all the storage conditions. The analysis also revealed that 15 °C was the most suitable storage condition with the favourable PLSR results (R > 0.50) in all the examined parameters. Moreover, variations on the BP of the samples with respect to the different storage conditions were correctly classified with over 90 % and 80 % accuracies using the PCA and LDA, respectively. Thus, the study indicates that the LLBI technique is feasible and can be a useful tool for a non-destructive quality measurement and classification of sweet potatoes under different storage conditions.

Non-destructive quality monitoring for horticultural products by means of optical imaging methods have gained wide interest in recent years. This study sought to investigate the potential use of laser-light backscattering imaging technique (LLBI) for non-invasive quality evaluation of sweet potatoes of different varieties after being harvested and stored at ambient temperature. A total of 360 newly harvested samples from the three varieties of locally-produced sweet potatoes in Malaysia i.e. Keledek Anggun 3, Keledek Jingga, and Keledek Kuning were purchased and stored in an ambient room temperature (28–30 °C) for a period of twenty one (21) days. After each 7-day storage, respective samples were taken out and backscattering images (BSI) were acquired using a charge-coupled device (CCD) camera attached with laser diodes emitting lights at 658 nm and 780 nm wavelengths, respectively. Quality attributes such as moisture content (MC), soluble solid content (SSC), textural properties (hardness, fracturability, adhesiveness), and flesh color properties (L*, a*, b*) as reference quality parameters (QP) were measured right after BSI acquisitions. Multiple Linear Regression (MLR) was applied to correlate and predict the relationship between the extracted backscattering parameters (BP) and the QP. Results revealed that there were significant changes (P 0.70) with BP, particularly the Keledek Kuning variety. The 658 nm wavelength showed better prediction results than 780 nm with r > 0.85 in measuring the textural properties. Thus, the study demonstrated the feasibility of LLBI as a useful non-destructive technique to evaluate the quality of sweet potatoes and can be further utilized for online optical quality grading.

A dynamic mathematical model was used in this study to describe the mass transfer and reaction kinetics of a fouled α–CGTase–CNF layer in a biocatalytic membrane reactor (BMR) system. BMR performance was evaluated based on the effect of substrate concentration and pneumatic gauge pressure on the permeate flux, total permeate volume, starch conversion, and α-CD production. A model is introduced based on the layer of mass limit as the resistance blocking mechanism with reaction kinetics on the fouled α–CGTase–CNF layer. Important unknown parameters of the constants describing the layer resistance, KML0 and the kinetic constant of Michaelis-Menten, kcat, for mass transfer and its reaction kinetics, were successfully estimated at 3.9 × 107 min/mL and 216.18 mg-starch/cm3⋅U⋅min, respectively, using the proposed models. The study found that the kcat value corresponding to the maximum efficiency of the enzyme on starch cyclisation was a critical parameter in the prediction of the BMR dynamic profiles. Thus, the proposed model in this study can be used for further development of the BMR system, with excellent hydrodynamic and reaction performance.