Table 2 Non-destructive methods to determine quality characteristics of fruits and vegetables (Zhang et al. 2014; Dhiedt et al. 2021; Gupta et al. 2022a)
Non-destructive technique | Quality characteristics | Function | Advantages | Limitations |
|---|---|---|---|---|
Impact test | Firmness and internal damage | The primary function of an impact test is to assess the toughness and resilience of materials, especially metals and polymers | Relatively simple and standardized testing procedures are available for various materials | It may not capture the complete behavior of a material under dynamic loading conditions |
NMR | Maturation, freeze burn, heat injury worm infestation, sugar content, moisture, and oil content | NMR spectroscopy measures the interaction of atomic nuclei with magnetic fields | NMR can determine the 3D structure of molecules, making it invaluable for identifying compounds and elucidating molecular structures | NMR can determine the 3D structure of molecules, making it invaluable for identifying compounds and elucidating molecular structures |
MRI | Freeze burn, morphology,core breakdown and insect infestation | MRI, or Magnetic Resonance Imaging, is a medical imaging technique that uses strong magnetic fields and radio waves to create detailed images | MRI does not involve ionizing radiation, making it safer than some other imaging methods | MRI machines are expensive to purchase and maintain, making the procedure relatively costly |
X-ray | Moisture content, freeze burn, enzymatic browning, bruises, tissue damage and insect infestation | The primary function of X-ray is to check tissue damage, insect infestation, enzymatic browning etc | X-ray imaging is generally quick, providing rapid results for medical and industrial applications | Incorrect use or overexposure to X-rays can be harmful, so proper safety measures are crucial |
NIR | Total soluble solids, firmness, acidity, sugar content, freeze burn,post-harvest damage, fat and protein content | NIR spectroscopy is a non-destructive analytical technique that utilizes the near-infrared region of the electromagnetic spectrum (typically 780–2500 nm) to analyze the composition of materials | NIR spectroscopy allows for the analysis of samples without altering or damaging them | NIR spectroscopy is surface-sensitive and can only analyze the outer layer of a sample, limiting its use for certain applications |
Acoustic | Firmness, internal defects, and cavity detection | Acoustic technology refers to the use of sound waves to transmit, receive, or process information. It has various applications across different fields | Acoustic technology can operate in various media, including air, water, and solids. This versatility allows it to be applied in diverse fields and environments | The resolution of acoustic imaging systems may not be as high as some other imaging modalities like MRI |
UV–VIS spectroscopy | Carotene, chlorophyll, and tannin | It involves measuring the absorption of ultraviolet (UV) and visible (VIS) light by a sample to obtain information about its electronic structure, concentration, and chemical composition | UV–VIS spectroscopy is versatile and can be applied to a wide range of compounds, including organic and inorganic molecules, ions, and biomolecules | High-quality UV–VIS spectrophotometers can be expensive, which can be a limitation for some laboratories |
Fluorescence spectroscopy | Freshness, ripeness, and surface blemishes | In fluorescence spectroscopy, a sample is exposed to a specific wavelength of light (the excitation wavelength), typically from an external light source such as a laser or lamp | Fluorescence spectroscopy is highly sensitive and can detect even trace amounts of fluorescent compounds in a sample | One of the significant limitations of fluorescence spectroscopy is that the sample must contain fluorescent molecules or be labeled with fluorescent probes. Not all compounds exhibit fluorescence |
Ultrasound | Maturity defects,sugar content, firmness moisture and oil content | Ultrasound in food processing is a technology that utilizes high-frequency sound waves to manipulate, analyze, or process food products | Ultrasound is generally more cost-effective compared to other imaging techniques like MRI | Ultrasound may have lower resolution compared to other imaging modalities like MRI or CT, making it less suitable for detailed imaging of certain structures |