Visible and Hyperspectral Imaging Systems for the Detection and Discrimination of Mechanical and Microbiological Damage of Mushrooms

Horticultural products such as mushrooms are exposed to environmental conditions during their postharvest life, which may affect product quality. Loss of whiteness during storage is particularly important in the mushroom industry. Rough handling and distribution, fruiting body senescence and bacterial infections are among the main causes of mushroom discolouration. The aim of this work was to study the use of visible and hyperspectral imaging (HSI) systems for the detection and discrimination of mechanical and microbiological damage of mushrooms. This piece of research involved a) monitoring the browning of mushroom with visible computer imaging systems, b) investigating the effect of mechanical damage on the kinetics of enzymes responsible for mushroom browning, c) exploring the potential use of Vis-NIR HSI to predict PPO activity in mushroom caps and d) studying the potential application of Vis-NIR HSI for microbial and viral detection on mushroom caps and for their discrimination from mechanical damage. Results presented in this thesis show that the efficacy of commercial webcams was limited in the detection of mechanical damage on mushroom caps. Damage increased the activity of PPOs on mushroom pileipellis, but the effect of the extent of damage was not significant at the levels of study. Vis-NIR HSI showed some potential as a tool to estimate the activity of PPO enzymes on mushroom caps. The combination of HSI with chemometric tools allowed for the differentiation of mechanically and microbiologically damaged mushroom classes. Results from this study could be used for developing non-destructive monitoring systems for mechanical and microbiological damage detection and discrimination. The potential application of such systems as on-line process analytical tools would facilitate rapid assessment of mushroom quality.

Prediction of Polyphenol Oxidase Activity Using Visible Near-Infrared Hyperspectral Imaging on Mushroom (Agaricus bisporus) Caps.

Physical stress (i.e. bruising) during harvesting, handling and transportation triggers enzymatic discoloration of mushrooms, a common and detrimental phenomenon largely mediated by polyphenol oxidase (PPO) enzymes. Hyperspectral imaging (HSI) is a non-destructive technique that combines imaging and spectroscopy to obtain information from a sample. The objective of this study was to assess the ability of HSI to predict the activity of PPO on mushroom caps. Hyperspectral images of mushrooms subjected to various damage treatments were taken, followed by enzyme extraction and PPO activity measurement. Principal component regression (PCR) models (each with 3 PCs) built on raw reflectance and multiple scatter corrected (MSC) reflectance data were found to be the best modeling approach. Prediction maps showed that the MSC model allowed for compensation of spectral differences due to sample curvature and surface irregularities. Results reveal the possibility of developing a sensor which could rapidly identify mushrooms with higher likelihood to develop enzymatic browning and hence aid produce management decision makers in the industry

Visible Near-Infrared Hyperspectral Imaging for the Identification and Discrimination of Brown Blotch Disease on Mushroom (Agaricus bisporus) Caps

Brown blotch, caused by pathogenic Pseudomonas tolaasii (P. tolaasii), is the most problematic bacterial disease in Agaricus bisporus mushrooms. Although it does not cause any health problems, it reduces the consumer appeal of mushrooms in the market place, generating important economical losses worldwide. Hyperspectral imaging (HSI) is a non-destructive technique that combines imaging and spectroscopy to obtain information from a sample. The objective of this study was to investigate the use of HSI for brown blotch identification and discrimination from mechanical damage on mushrooms. Hyperspectral images of mushrooms subjected to i) no treatment, ii) mechanical damage or iii) microbiological spoilage were taken during storage and spectra representing each of the classes were selected. Partial least squares- discriminant analysis (PLS-DA) was carried out in two steps: i) discrimination between undamaged and damaged mushrooms and ii) discrimination between damage sources (i.e. mechanical or microbiological). The models were applied at a pixel level and a decision tree was used to classify mushrooms into one of the aforementioned classes. A correct classification of \u3e95% was achieved. Results from this study could be used for the development of a sensor to detect and classify mushroom damage of mechanical and microbial origin, which would facilitate the industry to make rapid and automated decisions to discard produce of poor marketability

Методы определения цветовых характеристик растительного сырья. Обзор

Food product quality defines a complex of food product properties such size, shape, texture, color and others, and determines acceptability of these products for consumers. It is possible to detect defects in plant raw materials by color and classify them by color characteristics, texture, shape, a degree of maturity and so on. Currently, the work on modernization of color control systems has been carried out for rapid and objective measuring information about color of plant raw materials during their harvesting, processing and storage. The aim of the work is to analyze existing methods for determining color characteristics of plant raw materials described in foreign and domestic studies. Also, this paper presents the results of the experimental studies that describe the practical use of methods for measuring food product color. At present, the following methods for determining color characteristics by the sensor analysis principle are used: sensory, spectrophotometric and photometric. These methods have several disadvantages. Therefore, computer vision has found wide application as an automated method for food control. It is distinguished by high confidence and reliability in the process of determining freshness, safety, a degree of maturity and other parameters of plant raw materials that are heterogeneous in terms of the abovementioned indicators. The computer vision method is realized in the following systems: conventional, hyperspectral and multispectral. Each subsequent system is a component of the preceding one. Materials presented in the paper allow making a conclusion about the effectiveness of the computer vision systems with the aim of automatic sorting and determining quality of plant raw materials in the food industry.Качество пищевых продуктов обусловливает совокупность свойств продукции, таких как размер, форма, текстура, цвет и другие, и определяет приемлемость данной продукции для потребителя. По цвету можно определить дефекты в растительном сырье и классифицировать его по цветовым характеристикам, текстуре, размеру, форме, степени зрелости и т. д. В настоящее время ведутся работы по модернизации систем контроля цвета для быстрого и объективного измерения информации о цвете растительного сырья во время сбора, переработки, а также в процессе его хранения. Целью работы является проведение анализа существующих способов определения цветовых характеристик растительного сырья — они описаны в зарубежных и отечественных работах. Также в данной статье приводятся результаты экспериментальных работ, в которых рассказывается о практическом применении методов определения цвета пищевых продуктов. На сегодняшний день существуют следующие способы определения цветовых характеристик по принципу сенсорного анализа: органолептический, спектрофотометрический, фотометрический. Данные методы отличаются некоторыми недостатками, поэтому в качестве автоматизированного способа контроля пищевых продуктов широкое применение нашло компьютерное зрение. Он отличается высокой достоверностью и надежностью в процессе определения свежести, безопасности, степени зрелости и других параметров растительного сырья, отличающегося неоднородностью по перечисленным выше показателям. Метод компьютерного зрения находит свою реализацию в следующих системах: традиционной, гиперспектральной и многоспектральной. Каждая последующая система является составной частью предыдущей. Представленные в статье материалы позволяют сделать вывод об эффективности систем компьютерного зрения с целью автоматической сортировки и определения качества растительного сырья в пищевой промышленности

Metabolic Profiling and Fingerprinting for the Detection and Discrimination of Mechanical Damage in Mushrooms (Agaricus bisporus) during Storage

Horticultural products such as mushrooms are exposed to external agents during their postharvest life, which are going to affect product quality. Loss of whiteness during storage is particularly important in the mushroom industry. Rough handling and distribution of crops, fruiting body senescence, bacterial and viral infection are among the causes of mushroom discolouration. The aim of this work was to study the use of metabolic fingerprinting and metabolic profiling tools for the detection and discrimination of mechanical damage on mushrooms. This research involved: 1. Investigating whether the chemical changes induced by mechanical damage and ageing of mushrooms could be (a) detected in the mid-infrared absorption region using FTIR spectroscopy as a fingerprinting tool and (b) identified using chemometric data analysis. 2. Investigating metabolites in mushroom tissues using GC/MS as a metabolic profiling technique. The method was used to profile mushroom samples to identify metabolic markers for damage and to gain understanding of the many metabolic processes that occur. 3. Studying low levels of damage in mushrooms using NMR spectroscopy as a fingerprinting technique coupled with chemometrics to identify markers and determine metabolite structure. The results from this study show the usefulness of FTIR spectroscopy coupled with chemometric data analysis for evaluating damage in mushrooms with specific wavenumbers identified. Metabolic profiling using GC/MS has led to a library of metabolites being built. Specific metabolites have been identified as markers for damage

Molecular and Epidemiological Studies of Trichoderma aggressivum f. europaeum

Trichoderma aggressivum is the causal agent of severe green mould disease in the cultivated mushroom Agaricus bisporus (Samuels et al., 2002). This fungus was First isolated in Ireland in 1987 during an epidemic of green mould disease and has subsequently been isolated from mushroom farms across Europe and North America (Largeteau et al., 2010). There are two subspecies T. aggressivum f. aggressivum and T. aggressivum f. europaeum which are found in North America and Europe respectively, the latter is the subject of this work. The purpose of this study was to investigate the interaction of T. aggressivum with A. bisporus and mushroom substrate, to study the epidemiology of T. ag- gressivum in Bulk Phase III mushroom systems and to develop methods for the detection of T. aggressivum. A separate results chapter is presented for each area of research. T. aggressivum has specific attributes which allow it to grow better in mushroom substrate than other Trichoderma species, resist inhibition by A. bisporus metabolites and ultimately cause more severe reductions in mushroom yield (Largeteau et al., 2000b; Mumpuni et al., 1998). A proteomic method was employed to study the effect of mushroom substrate and A. bisporus tissue on T. aggressivum in vitro. Proteins involved in the oxidative stress response were upregulated in T. aggressivum in both treatments. In vivo the production of oxidative stress response proteins may be part of the ability of T. aggressivum to resist inhibition by the microbial population of mushroom substrate and by A. bisporus, thereby colonising the substrate and reducing mushroom yields (Largeteau et al., 2000b; Savoie et al., 2001a; Williams et al., 2003a). Much of the research on the epidemiology of T. aggressivum in mushroom production was performed in in situ spawn run systems. The Bulk Phase III system has become more common in Europe in recent years but there is little information about T. aggressivum in this system. Cropping experiments were carried out to investigate the epidemiology of T. aggressivum in Bulk Phase III with particular emphasis on the effect of bulk handling of spawn-run substrate on infection. Infection of Bulk Phase III substrate during bulk handling was shwon to be possible. The severity of infection depended on T. aggressivum load and on the amount of mixing performed during bulk handling. Identification of T. aggressivum can be problematic due to morphological similarities with Trichoderma harzianum and other Trichoderma species found on mushroom farms (Seaby, 1996a). The most common method for differentiating T. aggressivum from other species is the of PCR (Chen et al., 1999a) with selectve primers. In this study a real-time PCR method for identification of T. aggressivum was developed, novel selective primers were designed and compared to existing T. aggressivum selective primers and HPLC analysis of secondary metabolite profiles was assessed as an alternative method for the identification of T. aggressivum

Unravelling the bruising discoloration of Agaricus bisporus, the button mushroom

In this research the browning-discoloration caused by bruising of button mushrooms was analysed. Brown-discoloration of mushrooms can amongst others be caused by the picking and storage of mushrooms. Current day commercial hybrids can not be used for mechanical harvesting because mushrooms are sensitive for discoloration. Mechanical harvesting can be used to lower the production costs of mushrooms. To make this possible new hybrids should be available that have a higher tolerance for bruising-discoloration. To breed for new hybrids the cause of bruising-discoloration needs to be analysed. This was done by analysing the compounds (substrates) involved in brown-discoloration and to look at the genes involved. These genes code for the enzymes involved in the conversion of the substrates into the dark brown pigment melanin. The research was performed with commercial and wild strains and the offspring of a segregating population. </p

Mushrooms as a source of high-value bioactive molecules: conversion of ergosterol into vitamin D2, extraction, stabilisation, and a study using bakery products

[ES] Son numerosos los factores que contribuyen a la existencia de riesgo de déficit de vitamina D en la población europea. Este déficit favorece una menor absorción de calcio y fosfato, lo que puede causar varios trastornos de salud graves. Los alimentos naturales (no enriquecidos), por sí mismos, rara vez proporcionan suficiente vitamina D para prevenir el déficit, por lo que alimentos enriquecidos con vitamina D y/o suplementos de vitamina D pueden ayudar a prevenir la carencia cuando la exposición al sol es inadecuada. Sin embargo, la mayoría de los suplementos disponibles utilizan vitamina D que proviene de fuentes sintéticas, por lo que disponer de vitamina D de una fuente natural sería una alternativa para superar los problemas que conlleva el uso de aditivos sintéticos y contribuiría a proporcionar beneficios para la salud. En este sentido, la industria alimentaria está constantemente buscando ingredientes de fuentes naturales debido a sus propiedades multifuncionales, eficacia competitiva y efectos de menor toxicidad. Los hongos han sido una parte esencial de nuestra dieta durante muchos años debido a su rico contenido nutricional y abundancia en biomoléculas, específicamente ergosterol, una provitamina D2. Sin embargo, es necesario llegar a un número más significativo de individuos, por lo que, a la hora de pensar en un grupo de alimentos candidatos a la fortificación, es necesario elegir una matriz alimentaria como los cereales, principalmente el trigo, consumida por un gran porcentaje de la población mundial, y cuya harina se utiliza para desarrollar muchos productos alimenticios en todo el mundo. A lo largo de esta tesis se han propuesto alternativas para solventar alguna de las cuestiones arriba planteadas. Así, con el objetivo de obtener vitamina D de una fuente natural (hongos - vitamina D2) ha sido necesario desarrollar varias metodologías, desde la producción de hongos hasta la obtención de vitamina D2. Después de obtener la vitamina D2 su estabilización también es esencial, por lo que se han desarrollado metodologías de encapsulación para asegurar que se mantienen sus propiedades cuando se incorpora al producto final. Por otra parte, asumiendo que la vitamina D es esencial para muchas funciones en el organismo, pero principalmente para los huesos, fue necesario validar el concepto de que la vitamina D2 promueve la absorción de calcio. El trabajo llevado a cabo en la presente Tesis doctoral muestra que es posible obtener y estabilizar la vitamina D2 natural de los hongos e incorporarla a una matriz de harina utilizando tecnologías innovadoras de extracción, irradiación y encapsulación. Por otra parte, con el fin de maximizar los compuestos bioactivos presentes en los hongos, se ha realizado un estudio para complementar los sustratos donde se cultivan los hongos con silicato de calcio. Esta suplementación se ha relacionado con una mayor resistencia contra las plagas de insectos. Sin embargo, pocos estudios muestran el impacto de esta suplementación en los diferentes parámetros agronómicos de los hongos de ostra (Pleurotus ostreatus var. florida) o incluso su composición química y bioactividad (actividades antioxidantes, antibacterianas y antifúngicas)

Molecular and Microbiological Methods for the Detection and Measurement of Dry Bubble Disease caused by Lecanicillium (Verticillium) fungicola on Mushroom Farms

Agaricus bisporus (Lange) Imbach – button mushrooms is a commonly cultivated mushroom throughout Europe which has very significant agricultural production. Mushroom cultivation is a monoculture which is exposed to different pathogens and pests. The most economically significant mushroom pathogens is Lecanicillium fungicola, the causative agent of Dry Bubble disease. This mycoparasite is responsible for severe losses of cultivated mushrooms and can terminate all mushroom production. The purpose of this study was to investigate sources of dry bubble disease on mushroom farms using microbiological and molecular approaches. The main focus of the research was to develop a selective medium, to modify the existing selective method and molecular method – Real Time PCR for detection from samples originating from mushroom farms. The first task of this research was evaluate DNA extractions methods from pure cultures of L. fungicola and optimise PCR conditions using a know sets of primers. All tested DNA extraction method gave good genomic DNA useful for PCR. The next part of this research was identify and detect of L. fungicola in samples originating from mushroom farms. A PCR assay was developed and optimised for the detection of L. fungicola in casing soil and other mushroom farm debris. Four different methods were evaluated for the isolation of DNA from soil containing different concentrations of conidia of L. fungicola including manual extraction and commercially available kits. Only two methods succeeded extracted L. fungicola DNA from samples containing soil and casing. The primers for detection of L. fungicola designed by Zijlstra et al. (2007, 2008 and 2009) gave a 102 bp amplification product and this primer set was tested in PCR reactions for A. bisporus and other mushroom pathogens such as Cladobotryum mycophilum, Mycogone perniciosa and Trichoderma sp. and also Aspergillus fumigatus. On this research also was designed a selective primers for Lecanicillium fungicola detection from mushroom farms using ITS and MAT1-2-1 region. It was not possible to find truly specific primers for this purpose but some of the sets of primers generated can be used for in-vitro test for detection and identification L. fungicola from A. bisporus tissues. This study also succeeded in designing selective media for detection of L. fungicola from mushroom farm samples. Lecanicilium fungicola selective medium already exists (Rinker et al., 1993), but the growth of L. fungicola is very slow due to the inhibitive nature of the ingredients on fungal growth. A modified selective medium and novel selective medium were developed to enable rapid and consistent detection of L. fungicola from contaminated soil and casing samples after 6 days of incubation. Mushroom farms visits were performed for detection of L. fungicola from different locations and stages of the crop cycle from spawn running to 3rd flush. Lecanicillium fungicola was detected by microbiological tests using novel and modified selective media and molecular method Real Time PCR – TaqMan test using the above mentioned primers