Recent Developments and Applications of Hyperspectral Imaging for Quality Evaluation of Agricultural Products: A Review

Food quality and safety is the foremost issue for consumers, retailers as well as regulatory authorities. Most quality parameters are assessed by traditional methods, which are time consuming, laborious, and associated with inconsistency and variability. Non-destructive methods have been developed to objectively measure quality attributes for various kinds of food. In recent years, hyperspectral imaging (HSI) has matured into one of the most powerful tools for quality evaluation of agricultural and food products. HSI allows characterization of a sample's chemical composition (spectroscopic component) and external features (imaging component) in each point of the image with full spectral information. In order to track the latest research developments of this technology, this paper gives a detailed overview of the theory and fundamentals behind this technology and discusses its applications in the field of quality evaluation of agricultural products. Additionally, future potentials of HSI are also reported.     

高光谱图像法对稻谷贮藏中五种常见真菌生长拟合及区分

利用高光谱成像系统（HIS）获取稻谷贮藏中常见真菌（黑曲霉、米曲霉、杂色曲霉、构巢曲霉、桔青霉）在马铃薯葡萄糖琼脂板上培养期间的高光谱图像,波峰709 nm处的光谱值和全波段光谱值的第一主成分得分两种方法构建真菌Gompertz函数的生长模拟模型。Gompertz函数拟合结果显示,五种真菌基于全波段光谱值PCA分析后的第一主成分得分建立的生长拟合模型R2为0.1781⁰.9501,基于波峰709 nm光谱值建立的拟合模型R2为0.9095⁰.9679,效果明显优于第一主成分得分的建模效果。另外,主成分分析（PCA）结合偏最小二乘法判别分析（PLS-DA）可以区分五种不同菌种。其中,训练集和测试集中,PLS-DA模型对培养48 h的黑曲霉、米曲霉、构巢曲霉、桔青霉四种真菌及对照组的区分准确率为100%;而对杂色曲霉,训练集区分准确率为100%,测试集的区分率为33.33%。结果表明高光谱图像技术能够用来对真菌种类进行区分。      

库尔勒香梨感官及理化指标的定量无损检测

目的 利用高光谱成像技术建立库尔勒香梨分级指标的快速检测方法.方法 选择采摘期香梨作为研究样本,以颜色(a*)、硬度(带皮硬度,hardness)和可溶性固形物(soluble solids content,SSC)为研究指标,使用高光谱成像系统采集样本900～1700 nm范围波长的漫反射光谱.提取样本感兴趣区域(r...     

Strategies to reduce mycotoxin levels in maize during storage: a review

Maize (Zea mays L.) is one of the main cereals as a source of food, forage and processed products for industry. World production is around 790 million tonnes of maize because as a staple food it provides more than one-third of the calories and proteins in some countries. Stored maize is a man-made ecosystem in which quality and nutritive changes occur because of interactions between physical, chemical and biological factors. Fungal spoilage and mycotoxin contamination are of major concern. Aspergillus and Fusarium species can infect maize pre-harvest, and mycotoxin contamination can increase if storage conditions are poorly managed. Prevention strategies to reduce the impact of mycotoxin in maize food and feed chains are based on using a hazard analysis critical control point systems (HACCP) approach. To reduce or prevent production of mycotoxins, drying should take place soon after harvest and as rapidly as feasible. The critical water content for safe storage corresponds to a water activity (a _w) of about 0.7. Problems in maintaining an adequately low a _w often occur in the tropics where high ambient humidity make the control of commodity moisture difficult. Damage grain is more prone to fungal invasion and, therefore, mycotoxin contamination. It is important to avoid damage before and during drying, and during storage. Drying maize on the cob before shelling is a very good practice. In storage, many insect species attack grain and the moisture that can accumulate from their activities provides ideal conditions for fungal activity. To avoid moisture and fungal contamination, it is essential that the numbers of insects in stored maize should be kept to a minimum. It is possible to control fungal growth in stored commodities by controlled atmospheres, preservatives or natural inhibitors. Studies using antioxidants, essential oils under different conditions of a _w, and temperature and controlled atmospheres have been evaluated as possible strategies for the reduction of fungal growth and mycotoxin (aflatoxins and fumonisins) in stored maize, but the cost of these treatments is likely to remain prohibitive for large-scale use.     

The essential oil from Heteropyxis natalensis harv: Its antimicrobial activities and phytoconstituents

The essential oil obtained from Heteropyxis natalensis by steam distillation was tested for antimicrobial properties. Twenty five bacterial and four fungal species were used as test organisms in this study. These included animal and plant pathogens, food poisoning bacteria and mycotoxigenic fungal strains. The essential oil exhibited considerable inhibitory activities against all the test organisms. GC–MS analysis indicated the essential oil contained 1,8-cineole, limonene, β-myrcene, α-phellandrene and α-pinene.     

Formation of fumonisins and other secondary metabolites by Fusarium oxysporum and F. proliferatum: a comparative study

The principal aim of this study was to estimate the formation of fumonisins (FB₁ and FB₂), moniliformin (MON), and ergosterol (ERG) by Fusarium oxysporum and Fusarium proliferatum, while the formation of beauvericin (BEA) was estimated by the latter Fusarium species only. Moreover, the effect of temperature on the biosynthesis of mycotoxins was also evaluated. Fumonisins were formed by F. proliferatum, with the highest yield at 18°C (720.0–1976.6 µg g^?1 for FB₁, 74.2–670.8 µg g^?1 for FB₂) and only by three of four F. oxysporum strains at a very low level (0.02–4.77 µg g^?1 for FB₁, 0.02–2.15 µg g^?1 for FB₂). The amount of MON formed by F. proliferatum was the highest (p < 0.001) at 32°C (3056.87 µg g^?1), while MON biosynthesis by F. oxysporum was lower 227.54 µg g^?1 (p < 0.001). BEA was produced by F. proliferatum with the highest level at 25°C (p < 0.001). ERG–recognized as an indicator of fungal biomass development and as a consequence of mycotoxin formation–was found at the highest concentration at a biosynthesis temperature of 25°C for F. proliferatum and F. oxysporum (p < 0.001).     

Exo-metabolites of mycelial fungi isolated in production premises of cheese-making and meat-processing plants

Data were obtained on the species composition of mycelial fungi isolated from the air of workrooms and production premises in cheese-making and meat-processing plants. The strains studied were shown to be capable of producing various low molecular weight compounds. Many of them are mycotoxins such as α-cyclopiazonic acid (CPA), mycophenolic acid (MPA), citrinin, cladosporin, roquefortine and ergot alkaloids. The profiles of the secondary metabolites were used to elucidate the species’ names of the isolated strains.     

Occurrence of mycotoxigenic fungi and mycotoxins in animal feed from bihar,india

A total of 387 samples comprising animal feed, poultry feed and cattle cakes from India were examined in order to isolate mycotoxin-producing fungi as well as mycotoxins. Of 385 Aspergillus flavus group isolates 53% were capable of producing aflatoxins in liquid SMKY medium. Toxigenic strains of other mycotoxigenic fungi, viz A ochraceus, A versicolor, Penicillium citrinum and Fusarium moniliforme, were also recorded. In feed samples, beside the aflatoxins present in 139 samples zearalenone, ochratoxin A and citrinin were also recorded alone or as cocontaminants. A monsoon climate together with the socioeconomic conditions of this region are important determinants for the high incidence of mycotoxins in animal food.     

Applications of Hyperspectral Imaging in Chicken Meat Safety and Quality Detection and Evaluation: A Review

Currently, the issue of food safety and quality is a great public concern. In order to satisfy the demands of consumers and obtain superior food qualities, non-destructive and fast methods are required for quality evaluation. As one of these methods, hyperspectral imaging (HSI) technique has emerged as a smart and promising analytical tool for quality evaluation purposes and has attracted much interest in non-destructive analysis of different food products. With the main advantage of combining both spectroscopy technique and imaging technique, HSI technique shows a convinced attitude to detect and evaluate chicken meat quality objectively. Moreover, developing a quality evaluation system based on HSI technology would bring economic benefits to the chicken meat industry. Therefore, in recent years, many studies have been conducted on using HSI technology for the safety and quality detection and evaluation of chicken meat. The aim of this review is thus to give a detailed overview about HSI and focus on the recently developed methods exerted in HSI technology developed for microbiological spoilage detection and quality classification of chicken meat. Moreover, the usefulness of HSI technique for detecting fecal contamination and bone fragments of chicken carcasses are presented. Finally, some viewpoints on its future research and applicability in the modern poultry industry are proposed.