Early detection of insect infestation in stored grain based on head space analysis of volatile compounds

Insect infestation is a common problem for stored grain. Insects can cause quantitative losses as kernels are consumed by insects. Also, the appearance and organoleptic properties can be altered through physical damage and contamination by faeces, webbing and body parts of insects, respectively. Therefore, several detection techniques have been developed and applied to stored grains. Some methods demonstrate very high sensitivity but are relatively costly, and thus, are not affordable to the industry; whereas cheaper methods lack detection sensitivity. Consequently, volatile isolation techniques could be an alternative approach to monitor insects in stored grain. Odour detection is a useful tool for monitoring grain quality. It has become part of standard method for grading grain in the United States. Although identification of volatile compounds produced by fungi species has been extensively studied in most types of grains, this has been less done for insect infestation. This paper reviews the literature related to detection of insect infestation in stored wheat by using volatile isolation techniques. Keywords: Grain infestation, Insect detection methods, Volatile isolation techniques, Solid phase microextractio

Modelling of Seed Drying in Fluidised and Spouted Bed Dryers

Drying experiments were conducted in the fluidised bed dryer (FBD) and spouted bed dryer (SBD) at temperature 40-80°C using maize, rice and wheat seed samples. The experimental data were fitted into four thin-layer drying models by least square method. As a result, Page’s model and two-compartment model were the best-fitted models. Due to the limitation of these models, Page’s model and the twocompartment model were modified by adding the drying temperature term. Subsequently, these models could efficiently predict the drying curves under a wider range of temperatures with root mean square (RMS) of the MRpredicted - MRmeasured not over 0.035. Keywords: Drying model, Seed drying, Fluidised bed dryer, Spouted bed dryer, Drying air temperatur

Effect of nut-in-shell storage conditions on volatile profile in macadamia nuts

In order to study the effect of storage conditions on the volatile profile of macadamia nuts, both temperature and the presence of oxygen were controlled. Nuts-in-shell of variety 246 were stored at -18, 10 and 15°C. At each temperature, samples were stored in net bags and vacuum packed in EVOH (ethylene vinyl alcohol) for a period of 2 months. Prior to testing, samples were cracked and roasted. Analytical tests included peroxide value, p-anisidine and TBA (thiobarbituric acid number). Volatile compounds were isolated using Head-Space-Solid-Phase-Micro Extraction (DVB/PDMS/CAR). Volatiles were analysed by chromatography/mass spectrometry (GC/MS). The results show that at –18°C peroxide, p-Anisidine and TBA values were lower compared to the other 2 storage temperatures. This indicates that lipid degradation was lowest at this temperature. The main compounds found in volatile components of both fresh and roasted macadamia nut were hydrocarbons, aldehydes, and ketones. Several compounds deriving from lipid degradation and Maillard reaction were detected such as hexanal, thiazole. This indicates that changes in volatiles of macadamia nuts result from compounds present in macadamia nuts which were the precursors of volatile compounds produced during roasting. Storage materials which were net bag and EVOH showed no significant effect on volatile produced during 2 months storage trial. Volatiles generated depend mainly on processing steps such as roasting. The lipid degradation was minimised at low temperature. Therefore storage conditions for nut-in-shell influence the final macadamia kernel quality, especially shelf-life, as peroxide value and other lipid degradation product were used as criteria of shelf-life changes while volatile produced by Maillard reaction indicated roasting quality. Keywords: Macadamia, Volatiles, Storage conditions, Head-Space-Micro Extraction, Lipid change

Effects of preconditioning on quality of dried blueberries

Blueberries are a rich source of phenolic compounds, especially anthocyanins, which contributes to their high level of antioxidant activity. However, these compounds of significant health benefit will be degraded after the blueberries undergo various air drying processes. Drying of blueberries can be difficult due to the wax layer surrounding the fruit. The health properties may be reduced to a large extent due to long exposure to high temperature. In this study, a mechanical wax abrasive pretreatment is used to carefully remove the wax layer and reduce drying time. The abrasive drum was lined with medium grain sand paper and attached to a constant speed rotator. The amount of blueberries and the rotating time were optimized to reduce the damage to the blueberries. Rabbiteye blueberries cv. Climax were used as the test fruit. A laboratory scale cabinet dryer was operated at temperatures between 50 and 90ºC with single stage and multistage drying strategies. The drying rates, colour and level of phenolic compounds and antioxidant activity were evaluated.Keywords: Blueberries, Air drying, Wax abrasive pretreatmen

Effects of High Temperature Drying on Rice Quality

Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is a Technical article from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 3 (2001): L. Wiset, G. Srzednicki, R. Driscoll, C. Nimmuntavin, and P. Siwapornak. Effects of High Temperature Drying on Rice Quality. Vol. III, May 2001

Antioxidant, enzyme inhibitory and antiproliferative activity of polyphenolic-rich fraction of commercial dry ginger powder

Polyphenolic-rich fraction obtained from locally produced dry ginger powder in Brahmaputra valley, India, and commercially available dry ginger (Zingiber officinale) rhizome powder consisted of [6]-gingerol (41.9%), [6]-shogaol (24.3%), 1-dehydro-6-gingerdione (8.6%), [8]-gingerol (7.2%), [10]-gingerol (5.1%), [6]-paradol (5.9%) and [4]-gingerol (3.6%). Traces of methyl-[6]-gingerol and methyl-[8]-gingerol (both at 1.8%) were also detected. The fraction exhibited high antioxidant capacity [total phenolics (TP), ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC) and cellular antioxidant activity (CAA assay)], effectively inhibited isolated digestive enzymes (α-glucosidase, pancreatic lipase and angiotensin converting enzyme) and inhibited the proliferation of colon (HT29; IC50 of 1.06 ± 0.02 mg mL−1) and gastric (AGS IC50 of 1.29 ± 0.03 mg mL−1) adenocarcinoma cells, without affecting the proliferation of their nontransformed counterparts (IC50 > 2.0 mg mL−1). This case study demonstrates that locally produced and commercially available dry ginger powder from Brahmaputra valley, India, retains numerous food components that may enhance human health

Effects of preconditioning on quality of dried blueberries

Abstract Blueberries are a rich source of phenolic compounds, especially anthocyanins, which contributes to their high level of antioxidant activity. However, these compounds of significant health benefit will be degraded after the blueberries undergo various air drying processes. Drying of blueberries can be difficult due to the wax layer surrounding the fruit. The health properties may be reduced to a large extent due to long exposure to high temperature. In this study, a mechanical wax abrasive pretreatment is used to carefully remove the wax layer and reduce drying time. The abrasive drum was lined with medium grain sand paper and attached to a constant speed rotator. The amount of blueberries and the rotating time were optimized to reduce the damage to the blueberries. Rabbiteye blueberries cv. Climax were used as the test fruit. A laboratory scale cabinet dryer was operated at temperatures between 50 and 90ºC with single stage and multistage drying strategies. The drying rates, colour and level of phenolic compounds and antioxidant activity were evaluated

A soft computing tool for species classification and prediction of glucomannan content in Amorphophallus genus

The proposed work aims at designing a classification system for automatic identification of A. muelleri species, grown as a potential cash crop in many Asian countries, from the DNA fingerprints of Amorphophallus genus. Four sets of 48 DNA fingerprints belonging to 37 species of the Amorphophallus genus, developed with the help of four different primers are considered for the experiment, with an objective to identify only the fingerprints of the species of interest. A second experimental setup deals with the automatic classification of species containing high amounts of glucomannan from the same set of DNA fingerprints of the Amorphophallus genus. For each set of 48 DNA fingerprints generated with a specific primer, the DNA fingerprints are preprocessed to extract a 42 dimensional feature vector which is used to generate a k-Nearest Neighbor based classifier based on the Leave One Out Cross Validation protocol. Final classification based on outputs from individual classifiers constructed with respect to the four different primers is performed according to a n-star consensus strategy. The n-star consensus predicts species A. muelleri with cent per cent accuracy while it predicts species containing glucomannan with a more modest accuracy of 81.25%