Quantification of resistant starch content in rice after hydrothermal treatments using terahertz spectroscopy.

Since hydrothermal treatments can enhance resistant starch (RS) content in rice and provide health benefits when consumed, a less laborious and non-destructive method to determine RS content is needed. Terahertz (THz) spectroscopy is hypothesized as a suitable method to quantify RS content in rice after hydrothermal treatment with its sensitivity for the intermolecular forces increase in the formation of RS. In this study, we first used the traditional in vitro hydrolysis method to determine the content of RS in rice. Then, the potential of starch absorbance peaks to quantify RS content after three commonly used hydrothermal methods, soaking, mild heat-moisture treatment, and parboiling, was investigated. The second derivative intensities of the peak at 9.0, 10.5, 12.1, and 13.1 THz were confirmed as being correlated with RS content and showed the high accuracy to predict RS content in samples (R2 > 0.96). Our results indicate the RS content of hydrothermally treated rice can be accurately quantified using these peaks.

Enhancing Paddy Rice Preservation in Small-Scale Barns: Comparative Analysis of Hot Air-Drying Techniques and Ventilation Impact on Quality and Energy Efficiency.

This investigation explores the effectiveness of hot air-drying and ambient ventilation techniques in enhancing the storage quality of Khao Dok Mali 105 paddy rice within small-scale barns in Northeast Thailand. Through comprehensive analysis of moisture and temperature dynamics, the research revealed that an optimized main air pipe system significantly reduces moisture content from 25% db to a desirable 16% db, outperforming alternative systems. Spatial assessments within the barn highlighted the importance of placement, showing that front sections achieved lower moisture levels. This underscores the need for uniform moisture distribution and temperature management to prevent quality degradation. Notably, after 84 h of drying, variations in moisture content across different barn locations emphasized the critical role of environmental control. These insights pave the way for advancing grain storage practices, focusing on strategic ventilation and environmental monitoring to ensure rice quality over time. This study not only challenges traditional methods but also offers significant practical implications for optimizing small-scale rice storage, providing a pathway towards sustainable post-harvest processing in resource-constrained environments.

Characterization of time-series fluorescence properties of bean sprouts during storage using excitation emission matrix and fluorescence imaging.

Soybean (Glycine max (L.) Merr.) and mung bean (Vigna radiata L.) are popular varieties of bean sprouts, which are used in various Asian cuisines. The freshness of bean sprouts reduces at fast rate during storage. Hence, determining index of monitoring the state of sprouts is required to prevent unnecessary food loss, which is also linked to economical loss. The aim of this study is to reveal fluorescence characteristic of bean sprouts and investigate its potentiality for tracking the freshness state of bean sprouts. The fluorescence spectroscopy and imaging were used. For fresh bean sprouts, the Excitation-Emission Matrix (EEM) showed two fluorescence regions: Excitation (Ex) 270-300 nm with Emission (Em) 300-400 nm and Ex 300-350 nm with Em 400-450 nm, which are suspected to be amino acids and vitamins, respectively. When browning process started, the new fluorescence region occurred at Ex 400-450 nm with Em 450-550 nm. Consistent with EEM, under 365 nm, bean sprouts initially had blue fluorescence emission, and later changed to green when they start spoiling. However, due to higher emission, 420 nm-excitation wavelength was preferable for detecting browning part. With these basic fluorescence information, further application on inspecting both physical change and chemical change of bean sprouts can be easily established.

Investigating the characteristics of fluorescence features on sweet peppers using UV light excitation.

Sweet peppers are popular worldwide due to their nutrition and taste. Conventional vegetable tracing methods have been trialed, but the application of such labels or tags can be laborious and expensive, making their commercial application impractical. What is needed is a label-free method that can identify features unique to each individual fruit. Our research team has noted that sweet peppers have unique textural fluorescence features when observed under UV light that could potentially be used as a label-free signature for identification of individual fruit as it travels through the postharvest supply chain. The objective of this research was to assess the feature of these sweet pepper features for identification purposes. The macroscopic and microscopic images were taken to characterize the fluorescence. The results indicate that all sweet peppers possess dot-like fluorescence features on their surface. Furthermore, it was observed that 93.60% of these features exhibited changes in fluorescence intensity within the cuticle layer during the growth of a pepper. These features on the macro-image are visible under 365 nm UV light, but challenging to be seen under white LEDs and to be classified from the fluorescence spectrum under 365 nm light. This research reported the fluorescence feature on the sweet pepper, which is invisible under white light. The results show that the uniqueness of fluorescent features on the surface of sweet peppers has the potential to become a traceability technology due to the presence of its unique physical modality.

Determining changes in crystallinity of rice starch after heat-moisture treatment using terahertz spectroscopy.

To investigate the potential of Fourier-transform terahertz (FT-THz) spectroscopy to follow crystalline structure changes in rice starch after heat-moisture treatment (HMT), we measured the crystallinity by X-ray diffraction (XRD) spectra and found its correlation with THz spectra. According to A-type crystal structure and Vh-type crystalline structure of amylose-lipid complex (ALC) in rice starch, crystallinity is divided into A-type and Vh-type. The intensity of second derivative spectra peak at 9.0 THz was highly correlated with both A-type and Vh-type crystallinity. Additionally, other three peaks at 10.5 THz, 12.2 THz, and 13.1 THz were also sensitive to Vh-type crystalline structure. These results indicate that after HMT, the crystallinity of ALC (Vh-type) and A-type starch can be quantified using THz peaks.

Characterization of fluorescence properties of wounds on soybean seedlings during healing process using excitation emission matrix and fluorescence imaging.

To establish a simple and nondestructive method for measuring plant wound-healing ability, we characterized the fluorescence characteristics of wounds on hypocotyl of soybean seedlings during healing process. Wounds were manually created on the stem of soybean seedlings 7 days after sowing. The fluorescence time-series characteristics of the wounds were measured until 96 h after wounding using excitation emission matrix (EEM) and fluorescence images excited by wavelength of 365 nm. In the EEM of wounds, three main fluorescence peaks were observed, and the intensity decreased with time after wounding. The reddish color due to chlorophyll in fluorescence images also decreased with healing process. In addition, microscopic observation of the wounded tissue using a confocal laser microscope showed that the intensity of lignin or suberin like fluorescence increased with healing time, which might have blocked the excitation light. These results suggest that UV-excited fluorescence can be a new indicator of the healing ability of plant tissues.

Antioxidant assessment of agricultural produce using fluorescence techniques: a review.

The study of bioactive compounds like food antioxidants is getting huge attention and curiosity by researchers and other relevant stakeholders (e.g., food and pharmaceutical industries) due to their health benefits. However, the currently available protocols to estimate the antioxidant activity of foods are time-consuming, destructive, require complex procedures for sample preparation, need technical persons, and not possible for real-time application, which are very important for large-scale or industrial applications. On the other hand, fluorescence spectroscopy and imaging techniques are relatively new, fast, mostly nondestructive, and possible to apply real-time to detect the antioxidants of foods. However, there is no review article on fluorescence techniques for estimating antioxidants in agricultural produces. Therefore, the present review comprehensively summarizes the overview of fluorescence phenomena, techniques (i.e., spectroscopy and computer vision), and their potential to monitor antioxidants in fruits and vegetables. Finally, opportunities and challenges of fluorescence techniques are described toward developing next-generation protocols for antioxidants measurement. Fluorescence techniques (both spectroscopy and imaging) are simpler and faster than available traditional methods of antioxidants measurement. Moreover, the fluorescence imaging technique has the potential to apply in real-time antioxidant identification in agricultural produce such as fruits and vegetables. Therefore, this technique might be used as a next-generation protocol for qualitative and quantitative antioxidants measurement after improvements like new material technologies for sensor (detector) and light sources for higher sensitivity and reduce the cost of implementing real-world applications.

Macroscopic and microscopic characterization of fluorescence properties of multiple sweet pepper cultivars (Capsicum annuum L.) using excitation-emission matrix and UV induced fluorescence imaging.

Sweet peppers are a popular vegetable with various surface colors, such as green, purple, red, or yellow. To characterize the unique fluorescence properties associated with a broad range of sweet peppers of various colors (14 varieties), a fluorescence spectrofluorometer and imaging were used. The results showed that all cultivars in the experiment had blue fluorescence emissions when excited with light in the UV-A region, while chlorophyll fluorescence could be observed in green peppers. The emitted blue fluorescence originated from the epidermis (cuticle layer). The color distribution of these sweet peppers in the a* and b* color space were compared to the image obtained under white LED light. Yellow and red pepper cultivars have thicker, multiple cuticular wax layers and more distinct maturity stages than other sweet pepper varieties observed. With the establishment of this basic fluorescence database, further applications of fluorescence-based techniques and the unification of evaluation methods for pepper quality will be more easily established.

Hydrogen-Bond Configurations of Hydration Water around Glycerol Investigated by HOH Bending and OH Stretching Analysis.

Toward a comprehensive understanding of the mechanism of glycerol as a moisturizer, studies on the hydrogen-bond (HB) structure of hydration water, which is known to be disordered by glycerol, are insufficient. To this aim, we evaluated the HB configurations based on the HOH bending and OH stretching spectra of the hydration water from those of glycerol/water mixtures by subtracting the contributions of bulk water and glycerol using dielectric relaxation spectroscopy. Analysis of the HOH bending band showed that hydration water-donating HBs lose the intermolecular bending coupling with increasing glycerol by replacing the water-water HBs with water-glycerol HBs. The OH stretching band provided more detailed insight into the HB configuration, indicating that the double-donor double-acceptor and double-donor single-acceptor configurations in bulk water change to a predominantly double-donor single-acceptor configuration in hydration water around glycerol. The formation of more donor HBs than acceptor HBs may be due to the steric constrains by glycerol and/or differences in the partial charge on the oxygen atom between water and glycerol.

Response of sweet pepper autofluorescence against solar radiation.

Shades are adjusted in sweet pepper cultivation, based on solar exposure levels. Pyranometers and photosensitive films have recently been introduced to smart agriculture. However, there are no means of observing biological responses to solar exposure. In this study, we hypothesized that solar exposure levels affect the visible autofluorescence of sweet pepper under 365 nm illumination. To test this hypothesis, we cultivated sweet pepper plants under two exposure conditions, low (half of the normal) and high (the normal). Fluorescence photography (365 nm illumination) revealed that dark-fluorescent peppers only arise when cultivated under high-exposure conditions (0.7-fold decline at emission of 390 nm for high-exposure conditions). Microscopic and spectroscopic observations showed that blue autofluorescence was accompanied by an accumulation of UVB pigments (1.2-factor increase in the absorbance at 300 nm) and epidermal development (1.3-fold thicker cell wall). This study suggests that the autofluorescence of sweet pepper can possibly be used to understand the response of crop to solar radiation at a fruit level in horticulture.

Japanese dace (Tribolodon hakonensis) fish freshness estimation using front-face fluorescence spectroscopy coupled with chemometric analysis.

Although fish and its related products are good sources of protein and unsaturated fatty acids, like omega-3 in the human diet, their shelf-life is limited by biochemical and microbial changes. In this study, a front-face fluorescence spectroscopy technique was used to acquire Excitation-emission matrices (EEM) to monitor Japanese dace (Tribolodon hakonensis) fish freshness degradation during storage. EEM of Japanese dace fish parts (intact eyeball and surface-containing scales), excitation from 220 to 585 nm and emissions from 250 to 600 nm, were measured at different times during storage. To simplify the acquired complex spectra datasets from each fish part, the variables were reduced to those that were only significant/important (those with higher positive or negative correlation) for K value prediction, and as an index of freshness. Partial least square regression (PLSR) results demonstrated that combining the fluorescence EEM of the eyeball and surface-containing scales the best monitoring of fish freshness; excitation at 280 and 350 nm for both the eyeball and surface-containing scales, with 2.84 and 0.96 as RMSE and R2, respectively. These findings demonstrate that multiple excitation fluorescence approaches can be convenient for the freshness evaluation of fish.

Assessment of chalkiness index of Sake rice using transmission imaging.

The higher chalkiness level of the white core kernel is prone to breakage during the high degree polishing. So, grading white core kernel based on chalkiness level is crucial to making premium quality Sake (rice wine) in the brewing industry. The chalkiness level in the white core kernel is currently performed destructively. Thus, a chalkiness index is required to assess the level in the white core kernel. This research assesses the white core rice kernel based on the chalkiness index non-destructively. Here, the optical transmission property in the visible to near-infrared (VIS-NIR) region of rice was measured using a V-670 spectrophotometer equipped with an integrating sphere to investigate the variation of chalkiness level rice samples. The images were then acquired by transmission mode of four types of intact Sake rice kernel using blue light-emitting diodes (LEDs), green, red, and NIR LEDs in which the peak wavelength of the LEDs was 465 nm, 525 nm, 630 nm, and 830 nm, respectively. The result indicates that the rice samples were more penetrated and better visualized chalkiness by light in the NIR region. Therefore, the wavelength region in NIR showed better discrimination between transparent and opaque parts in white core's Sake rice. Furthermore, the proposed chalkiness index was inversely correlated with the gray-level intensity of the transmittance image. This gray value was significantly correlated (R2 = 0.89) with the chalkiness index in the NIR region. So, gray values of NIR transmittance images were identified as sensitive for chalkiness index, which would be applied for sorting the white core kernel with different levels of chalkiness in the Sake brewing industry.

UV excited fluorescence image-based non-destructive method for early detection of strawberry (Fragaria × ananassa) spoilage.

The soon spoiled strawberries need to be classified from healthy fruits in an early stage. In this research, a machine vision system is proposed for inspecting the quality of strawberries using ultraviolet (UV) light based on the excitation-emission matrix (EEM) results. Among the 100 fruits which were harvested and stored under 10 °C condition for 7 days, 7 fruits were confirmed to be spoiled by using a firmness meter. The EEM results show the fluorescence compound contributes to a whitish surface on the spoiled fruits. Based on the EEM results, UV fluorescence images from the bottom view of strawberries were used to classify the spoiled fruits and healthy fruits within 1 day after harvest. These results demonstrate the UV fluorescence imaging can be a fast, non-destructive, and low-cost method for inspecting the soon spoiled fruits. The proposed index related to the spoiling time can be a new indicator for qualifying strawberry.

Prediction of protein and oil contents in soybeans using fluorescence excitation emission matrix.

To investigate the potential of fluorescence spectroscopy in evaluating soybean protein and oil content, excitation emission matrix (EEM) was measured on 34 samples of soybean flours using a front-face measurement, and the accuracy of the protein and oil content prediction was evaluated. The EEM showed four main peaks at excitation/emission (Ex/Em) wavelengths of 230/335, 285/335, 365/475, and 435/495 nm. Furthermore, second derivative synchronous fluorescence (SDSF) spectra were extracted from the EEMs, and partial least square regression and support vector machine models were developed on each of the EEMs and SDSF spectra. The R2 values reached 0.86 and 0.74 for protein and oil, respectively. From the loading spectra, fluorescence at Ex/Em of 230-285/335 nm and 350/500 nm mainly contribute to the protein and oil content prediction, respectively. Those results revealed the potential of fluorescence spectroscopy as a tool for a rapid prediction of soybean protein and oil content.

Research Note: Nondestructive detection of super grade chick embryos or hatchlings using near-infrared spectroscopy.

Some unresolved questions in poultry science were addressed: what determines the yield of chick embryos or hatchlings; what kind of influence does egg yolk content have on embryonic development; and how to detect eggs producing super grade chicks? Since the yolk acts as a vital energy and nutrient reservoir for embryos, we hypothesized that a higher yolk content of similar sizes eggs would play an important role in embryo or chick viability during incubation, as well as at hatch. As experimental sample, we used ROSS 308 (broiler line) and a nondestructive spectroscopic absorbance method. The influence of high yolk content to embryonic heartbeat and chick yield (i.e., chick weight/egg weight) were then investigated. Embryonic heartbeat signal was measured indirectly using a prototype near-infrared sensor during incubation period. A positive influence was found in both cases. Similar size eggs with higher yolk content were found to significantly (P-value < 0.05) promote higher chick yield at hatch. This methodology may have the potential to be used to precision poultry production system, ornithology, developmental, or evolutionary biology in the near future.

Association of fruit, pericarp, and epidermis traits with surface autofluorescence in green peppers.

We investigated the association of blue fluorescence (excitation at 365 nm) with the traits of the fruit, pericarp, and epidermis in green peppers. The fruits were manually classified into two groups based on fluorescence brightness. The dark fluorescence group showed the accumulation of blue-absorbing pigments and a thicker cuticular structure, suggesting epidermal development.

Chick Embryo Growth Modeling Using Near-Infrared Sensor and Non-Linear Least Square Fitting of Egg Opacity Values.

Non-destructive monitoring of chick embryonic growth can provide vital management insights for poultry farmers and other stakeholders. Although non-destructive studies on fertility, hatching time and gender have been conducted recently, there has been no available method for embryonic growth observation, especially during the second half of incubation. Therefore, this work investigated the feasibility of using near-infrared (NIR) sensor-based egg opacity values-the amount of light lost when passing through the egg-for indirectly observing embryo growth during incubation. ROSS 308 eggs were selected based on size, mass and shell color for this experiment. To estimate the embryo size precisely, we fit various mathematical growth functions during incubation, based on the opacity value of incubated eggs. Although all the growth models tested performed similarly in fitting the data, the exponential and power functions had better performances in terms of co-efficient of determination (0.991 and 0.994 respectively) and RMSE to explain embryo growth during incubation. From these results, we conclude that the modeling paradigm adopted provides a simple tool to non-invasively investigate embryo growth. These models could be applied to resolving developmental biology, embryonic pathology, industrial and animal welfare issues in the near future.

Autofluorescence changes of tomato surface tissues during overripening.

We investigated the autofluorescence of tomato surface tissues during overripening at 25 °C for 13 days. Microscopic images and fluorescence spectra of tissues, including the epidermis and cuticle, were examined (excitation at 360 nm), revealing that the autofluorescence changes were related to the epidermis, particularly the fluorophores in the cuticle.

A Noise Tolerant Spread Spectrum Sound-Based Local Positioning System for Operating a Quadcopter in a Greenhouse.

Quadcopters are beginning to play an important role in precision agriculture. In order to localize and operate the quadcopter automatically in complex agricultural settings, such as a greenhouse, a robust positioning system is needed. In previous research, we developed a spread spectrum sound-based local positioning system (SSSLPS) with a 20 mm accuracy within a 30 × 30 m greenhouse area. In this research, a noise tolerant SSSLPS was developed and evaluated. First, the acoustic noise spectrum emitted by the quadcopter was documented, and then the noise tolerance properties of SSSounds were examined and tested. This was done in a greenhouse with a fixed quadcopter (9.75 N thrust) with the positioning system mounted on it. The recorded quadcopter noise had a broadband noise compared to the SSSound. Taking these SSSound properties into account, the noise tolerance of the SSSLPS was improved, achieving a positioning accuracy of 23.2 mm and 31.6 mm accuracy within 12 × 6 m for both Time-division Multiple Access (TDMA) and Frequency-division Multiple Access (FDMA) modulation. The results demonstrate that the SSSLPS is an accurate, robust positioning system that is noise tolerant and can used for quadcopter operation even within a small greenhouse.

Thermal oxidation assessment of Italian extra virgin olive oil using an UltraViolet (UV) induced fluorescence imaging system.

Extra virgin olive oil is a high-quality product with profound health benefits but is susceptible to degradation due to oxidation. Environmental conditions such as temperature, oxygen, and light, promote the oxidation process. From this perspective thermal oxidation stability is of primary concern in terms of food quality and safety. The ability to resist oxidation ensures continued nutritional and economic value. In this study, the thermal oxidation stability of four mono-cultivars of extra virgin olive oil from four different regions of Italy was studied. The samples underwent thermal treatment at 120 °C with measurements taken at regular time intervals over 180 min. To develop a simplified imaging system, the fluorescence characteristics of the samples during thermal exposure were measured using front-face fluorescence and transmittance spectroscopy in order to assess the changes that occur due to thermal exposure. Standard quality indices including; Peroxide value, acidity, K232, and K270, were also measured following IOC (International Olive Council) procedures. Image processing of both color and fluorescence images was done to ascertain cultivar responses to the thermal treatment. Fluorescence peaks associated with polyphenols, oxidation products, and chlorophyll were identified and monitored, and a comparison made between the different cultivars. Fluorescence peaks were observed at emission wavelengths 435, 465, and 570 nm, which are suspected to be products of oxidation and hydrolysis, respectively. The cultivars with a higher concentration of polyphenols showed greater resistance to the formation of oxidation products; an indication that they have a higher thermal stability. The B channel of the RGB color space was identified as being sensitive to changes in UltraViolet (UV) induced fluorescence images due to thermal exposure, and to enable the monitoring of the thermal stability of the different cultivars of extra virgin olive oil.