Marena Manley

Maize kernel hardness classification by near infrared (NIR) hyperspectral imaging and multivariate data analysis.

The use of near infrared (NIR) hyperspectral imaging and hyperspectral image analysis for distinguishing between hard, intermediate and soft maize kernels from inbred lines was evaluated. NIR hyperspectral images of two sets (12 and 24 kernels) of whole maize kernels were acquired using a Spectral Dimensions MatrixNIR camera with a spectral range of 960-1662 nm and a sisuChema SWIR (short wave infrared) hyperspectral pushbroom imaging system with a spectral range of 1000-2498 nm. Exploratory principal component analysis (PCA) was used on absorbance images to remove background, bad pixels and shading. On the cleaned images, PCA could be used effectively to find histological classes including glassy (hard) and floury (soft) endosperm. PCA illustrated a distinct difference between glassy and floury endosperm along principal component (PC) three on the MatrixNIR and PC two on the sisuChema with two distinguishable clusters. Subsequently partial least squares discriminant analysis (PLS-DA) was applied to build a classification model. The PLS-DA model from the MatrixNIR image (12 kernels) resulted in root mean square error of prediction (RMSEP) value of 0.18. This was repeated on the MatrixNIR image of the 24 kernels which resulted in RMSEP of 0.18. The sisuChema image yielded RMSEP value of 0.29. The reproducible results obtained with the different data sets indicate that the method proposed in this paper has a real potential for future classification uses.

Effect of Species Variation and Processing on Phenolic Composition and In Vitro Antioxidant Activity of Aqueous Extracts of Cyclopia spp. (Honeybush Tea)

The in vitro antioxidant activity of aqueous extracts prepared from four Cyclopia spp. (unfermented and fermented) was assessed using radical (ABTS *+) scavenging, ferric ion reduction, and inhibition of Fe2+-induced microsomal lipid peroxidation as criteria. Aqueous extracts of unfermented and fermented Aspalathus linearis (rooibos) and Camellia sinensis teas (green, oolong, and black) were included as reference samples. Qualitative and quantitative differences in phenolic composition were demonstrated for the Cyclopia spp. The xanthone glycoside, a.k.a. mangiferin, was the major monomeric polyphenol present in the Cyclopia extracts, with both unfermented and fermented C. genistoides extracts containing the highest quantities. Fermentation resulted in a significant reduction in extract yields and their total polyphenolic and individual polyphenol contents. Unfermented plant material should preferentially be used for preparation of extracts, as fermentation significantly ( P < 0.05) lowered antioxidant activity of all species, except in the case of C. genistoides, where the ability to inhibit lipid peroxidation was not affected. Unfermented plant material also retained the highest concentration of mangiferin. Overall, extracts of unfermented Cyclopia were either of similar or lower antioxidant activity as compared to the other teas. However, the presence of high levels of mangiferin merits the use of Cyclopia spp. and, in particular, C. genistoides, as an alternative herbal tea and potential dietary supplement.

Near Infrared Hyperspectral Imaging for the Evaluation of Endosperm Texture in Whole Yellow Maize (Zea maize L.) Kernels

Near infrared hyperspectral images (HSI) were recorded for whole yellow maize kernels (commercial hybrids) defined as either hard, intermediate, or soft by experienced maize breeders. The images were acquired with a linescan (pushbroom) instrument using a HgCdTe detector. The final image size was 570 x 219 pixels in 239 wavelength bands from 1000 to 2498 nm in steps of approximately 6.5 nm. Multivariate image cleaning was used to remove background and optical errors, in which about two-thirds of all pixels were removed. The cleaned image was used to calculate a principal component analysis (PCA) model after multiplicative scatter correction (MSC) and mean-centering were applied. It was possible to find clusters representing vitreous and floury endosperm (different types of endosperm present in varying ratios in hard and soft kernels) as well as a third type of endosperm by interactively delineating polygon based clusters in the score plot of the second and fourth principal components and projecting the results on the image space. Chemical interpretation of the loading line plots shows the effect of starch density and the protein matrix. The vitreous and floury endosperm clusters were used to make a partial least-squares discriminant analysis (PLS-DA) model, using four components, with a coefficient of determination (R(2)) for the y data (kernel hardness category) for the training set of over 85%. This PLS-DA model could be used for prediction in a test set. We show how the prediction images can be interpreted, thus confirming the validity of the PCA classification. The technique presented here is very powerful for laboratory studies of small cereal samples in order to produce localized information.

A review of triticale uses and the effect of growth environment on grain quality

Triticale (× Triticosecale sp. Wittmack ex A. Camus 1927) is an anthropogenic cereal designed to incorporate the functionality and high yield of wheat (Triticum spp. Linnaeus 1753) and durability of rye (Secale cereale Linnaeus 1753). The potential of triticale has remained largely unrealised, and in the 135 years since A. Stephen Wilson first crossed wheat and rye, triticale has mostly been used as animal feed. Growing demand for food resources has led to an increased interest in triticale development. Efforts to breed cultivars appropriate for baking have met with difficulty, although relatively new approaches to triticale end-use propose greater applicability for human consumption. Further, environmental awareness has generated interest in the use of triticale within biofuel production. We review environmental and genetic effects on triticale yield with a view towards increased demand on a hardy and useful cereal crop. We find triticale could satisfy many of the hopes originally placed upon it, and may be useful in foodstuffs and fuel, but only when growth environment is carefully considered.

Hardness Methods for Testing Maize Kernels

Maize is a highly important crop to many countries around the world, through the sale of the maize crop to domestic processors and subsequent production of maize products and also provides a staple food to subsistance farms in undeveloped countries. In many countries, there have been long-term research efforts to develop a suitable hardness method that could assist the maize industry in improving efficiency in processing as well as possibly providing a quality specification for maize growers, which could attract a premium. This paper focuses specifically on hardness and reviews a number of methodologies as well as important biochemical aspects of maize that contribute to maize hardness used internationally. Numerous foods are produced from maize, and hardness has been described as having an impact on food quality. However, the basis of hardness and measurement of hardness are very general and would apply to any use of maize from any country. From the published literature, it would appear that one of the simpler methods used to measure hardness is a grinding step followed by a sieving step, using multiple sieve sizes. This would allow the range in hardness within a sample as well as average particle size and/or coarse/fine ratio to be calculated. Any of these parameters could easily be used as reference values for the development of near-infrared (NIR) spectroscopy calibrations. The development of precise NIR calibrations will provide an excellent tool for breeders, handlers, and processors to deliver specific cultivars in the case of growers and bulk loads in the case of handlers, thereby ensuring the most efficient use of maize by domestic and international processors. This paper also considers previous research describing the biochemical aspects of maize that have been related to maize hardness. Both starch and protein affect hardness, with most research focusing on the storage proteins (zeins). Both the content and composition of the zein fractions affect hardness. Genotypes and growing environment influence the final protein and starch content and, to a lesser extent, composition. However, hardness is a highly heritable trait and, hence, when a desirable level of hardness is finally agreed upon, the breeders will quickly be able to produce material with the hardness levels required by the industry.

Meat quality characteristics of springbok (Antidorcas marsupialis). 1: Physical meat attributes as influenced by age, gender and production region

Springbok is the most extensively cropped game species in South Africa. The effects of age (adult, sub-adult, lamb), gender and production region on the physical attributes (pH(24), cooking and drip loss, Warner Bratzler shear force and colour) were determined using samples of the M. longissimus dorsi (LD) muscles of 166 springbok. Stressed animals had a higher (P<0.05) pH(24) (6.3±0.07), as observed in the meat originating from the Caledon region. This meat had lower (P<0.05) cooking loss (27.2±0.62%) and drip loss (1.8±0.08%) values in comparison to meat originating from the other regions. Inverse correlations were noted between pH(24) and drip loss (r=-0.26, P<0.01) and cooking loss (r=-0.42, P<0.001). Shear force values (kg/1.27cm diameter) correlated positively (r=0.25, P<0.01) with pH(24). Age-related effects on tenderness were small in comparison with pH(24) effects. CIELab colorimetric values were typical of game meat and venison (L(∗)<40, high a(∗) and low b(∗) values). It was noted that pH(24) correlated negatively (r=-0.51, P<0.001) and positively (r=0.33, P<0.001) with the hue-angle and the chroma value of colour, respectively. Springbok originating from Caledon had a significantly (P<0.05) higher a(∗) value, indicating meat to be more red with higher colour saturation.

Review: The application of near infrared spectroscopy to the measurement of bioactive compounds in food commodities

The perceived benefit of functional foods in the prevention or mitigation of degenerative diseases has stimulated the growth of the functional food market. This perception is based on the presence in these foods of specific molecules which have a positive pharmacological effect when consumed in sufficient quantities (bioactive compounds). The increasing market and consumer desire for quality food products with positive health benefits has created a need for efficient and accurate analytical methods for the quantification of bioactive compounds in raw materials and finished products. Near infrared (NIR) spectroscopy is a fast, non-destructive and accurate method of analysis that has been extensively utilised for the study of foods. NIR spectroscopy has been used to quantify carotenoids, polyphenols, fatty acids and glucosinolates in a wide range of food commodities, for example, wine, dairy products, tea, fruit, vegetables, herbs, spices and cereals. Often, these quantifications are based on data from both the NIR and visible spectral regions; several bioactive compounds are also considered pigments, hence the utility of the visible spectral region. Major classes of other bioactive compounds, including pre- and probiotics, have yet to be analysed using NIR spectroscopy. The use of NIR spectroscopy for analysis of bioactive compounds is expected to match the growth of the functional food and bioactive ingredients markets.

Tracking diffusion of conditioning water in single wheat kernels of different hardnesses by near infrared hyperspectral imaging.

The combination of near infrared (NIR) hyperspectral imaging and chemometrics was used to follow the diffusion of conditioning water over time in wheat kernels of different hardnesses. Conditioning was attempted with deionised water (dH(2)O) and deuterium oxide (D(2)O). The images were recorded at different conditioning times (0-36 h) from 1000 to 2498 nm with a line scan imaging system. After multivariate cleaning and spectral pre-processing (either multiplicative scatter correction or standard normal variate and Savitzky-Golay smoothing) six principal components (PCs) were calculated. These were studied visually interactively as score images and score plots. As no clear clusters were present in the score plots, changes in the score plots were investigated by means of classification gradients made within the respective PCs. Classes were selected in the direction of a PC (from positive to negative or negative to positive score values) in almost equal segments. Subsequently loading line plots were used to provide a spectroscopic explanation of the classification gradients. It was shown that the first PC explained kernel curvature. PC3 was shown to be related to a moisture-starch contrast and could explain the progress of water uptake. The positive influence of protein was also observed. The behaviour of soft, hard and very hard kernels was different in this respect, with the uptake of water observed much earlier in the soft kernels than in the harder ones. The harder kernels also showed a stronger influence of protein in the loading line plots. Difference spectra showed interpretable changes over time for water but not for D(2)O which had a too low signal in the wavelength range used. NIR hyperspectral imaging together with exploratory chemometrics, as detailed in this paper, may have wider applications than merely conditioning studies.

Meat quality characteristics of springbok (Antidorcas marsupialis). 2: Chemical composition of springbok meat as influenced by age, gender and production region.

The effects of age, gender and production region on the chemical, mineral and amino acid composition of the M. longissimus dorsi (LD) muscle of springbok were investigated. There was a significant gender(∗)region interaction for protein content - for the four production regions it varied between 18.80 and 21.16g/100g. The intramuscular fat (IMF) content of the LD muscle varied between 1.32 and 3.46g/100g. Females (3.13±0.28g/100g) had a higher (P<0.05) fat content than males (1.35±0.08g/100g). The IMF content of the adult (2.45±0.26g/100g) and sub-adult (2.50±0.28g/100g) categories was higher (P<0.05) in comparison to that of the lambs (1.32±0.11g/100g). An inverse correlation was noted between the IMF and moisture content (r=-0.49, P<0.001) of the meat. The two main amino acids were glutamic and aspartic acid, which contributed 2.47-2.74 and 2.31-2.54g/100g of dry matter, respectively. Phosphorous was the predominant mineral in the LD muscle (122.92-159.78mg/100g of dry matter), followed by potassium (119.44-131.25mg/100g of dry matter) and calcium (6.57-145.18mg/100g of dry matter). Production region had a significant effect on the mineral and amino acid composition of the meat, while the effects of age and gender were found to be insignificant.

The effect of dietary fish oil rich in n − 3 fatty acids on the organoleptic, fatty acid and physicochemical characteristics of ostrich meat

The effect of different levels of unrefined fish oil in the diet on ostrich Musculus iliofibularis was evaluated in a completely randomised experimental design, where a supplementary energy rich feed, containing 6.7% fish oil, was fed at four different levels over a 7-month period. An increase in the amount of fish oil consumed was found to have had no significant effect on the sensory characteristics of ostrich meat, although there was a tendency towards an increase in fishiness, for both aroma and flavour. Increased concentrations of fish oil, however, did have a significant effect on the aroma and flavour of the abdominal fat pads. The muscle pH(f) and muscle lightness (L*) revealed a significant reduction, with increased energy intake. However, the increased energy intake had no effect on the chemical composition (moisture, protein, fat, and ash content) of the meat. The fatty acid profile of both adipose tissue and muscle was altered as a result of the consumption of fish oil. The SFA concentration increased, while the PUFA concentration decreased with increasing dietary levels. The MUFA concentration remained constant for all four groups.