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Assessment of variance in measurement of hectolitre mass of wheat and maize, using equipment from different grain producing and exporting countriesEngelbrecht, Mandy L. 03 1900 (has links)
Thesis (Msc Food Sc (Food Science))--University of Stellenbosch, 2008. / South Africa as well as other grain producing and exporting countries’ grading systems strongly
relies on hectolitre mass (HLM) as a guide to grain quality. It is known that these countries use either
one of two types of HLM equipment. These devices consist of either a funnel or a cylindrical device
(chondrometer) with a measuring cylinder of known volume underneath which is then filled with grain
in a controlled manner. Subsequently the HLM devices from Australia, Canada, France, Germany,
South Africa, the United Kingdom (UK) and the United States of America (USA) were compared
using impurity free mixed wheat, single South African cultivars as well as maize samples.
Very little variation in HLM measurements within the HLM devices was observed with intra-class
correlation (ICC) agreement values close to one. Comparing the actual HLM values obtained with
the respective devices showed that the results obtained with the Australian device was significantly
(P < 0.05) higher, and those obtained with the South African devices significantly (P < 0.05) lower
compared to the other devices. As would be expected the devices showed better overall ICC
agreement when the HLM tests were performed with the single cultivar samples (ICC agreement =
0.762) as opposed to the mixed wheat samples (ICC agreement = 0.523). However, the HLM values
obtained with all the devices correlated well with each other (ICC consistency >0.90) indicating that
correction factors can therefore be developed to convert the HLM results between devices.
When ten South African devices were compared statistical differences were observed, but the
overall ICC agreement (0.975) and consistency (0.993) values indicated that the differences would
not be significant in practice. Hectolitre mass determinations performed on samples prior to and after
impurities have been removed revealed that the removal of impurities resulted in a significant (P <
0.05) increase in HLM. The effect of operator was shown to be significant (P < 0.05) when operators
with three levels of competency, i.e. skilled, semi-skilled and unskilled, were investigated.
The effect of wet and dry cycles on the HLM measurements was investigated and the results
showed that wetting and drying could change the integrity of the wheat. Moisture correction factors
cannot be applied to convert the HLM values of grain that underwent moisture changes as different
samples responded differently to the moisture treatments.
Comparing the respective devices with mixed maize samples (impurities not removed) very little
variation in HLM measurements within each device was observed. The comparison of the devices
revealed that the HLM measurements obtained with the Australian and French devices were
significantly (P < 0.05) higher and that obtained from the Canadian device significantly (P < 0.05)
lower compared to those obtained with the other devices. Again it was shown that the devices
correlate well (ICC consistency > 0.97) and that correction factors can be applied to convert HLM
results between devices. An alternative to the use of correction factors could be the replacement of
the South African device with the German device for both wheat and maize. The removal of impurities from the maize samples significantly (P < 0.05) increased the HLM
values. Therefore, it is likely that correction factors can be used to convert HLM values of maize
samples before and after removal of impurities.
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Assessment of hectolitre mass (HLM) equipment and HLM measurements of oatsEmvula, Sakeus 03 1900 (has links)
Thesis (MSc Food Sc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Hectolitre mass (HLM) measurements allow rapid and accurate determination of grain
density. HLM devices from different countries (Australia, Canada, France, Germany,
South Africa, the United Kingdom and the United States of America [USA]) have been
investigated for their effect on the HLM measurements of oats. In addition, the potential
of near infrared (NIR) hyperspectral imaging has been evaluated to distinguish between
oat samples with different HLM values. Comparing HLM measurements obtained from
the respective devices, the USA and the South African devices resulted in significantly
(P<0.05) lower HLM values compared to the other devices where as the German device
resulted in higher values (P<0.05) than the other devices. HLM values from all the
devices were highly correlated with intra-class correlation (ICC) consistency values of at
least 0.90. These high correlations would allow direct replacement of the South African
device with any of the other devices. The equipment selected as replacement should
ideally be calibrated according to the ISO 7971-3 standard (i.e. the device currently
used in Germany).
HLM values significantly (P<0.05) increased when oat samples were rubbed before
measurements were made, indicating the importance of continuation of this sample
preparation step. The investigation on the effect of the operator on HLM determinations
showed that the unskilled operator measured HLM values significantly different to those
obtained by the skilled operator. This emphasises the importance of training in spite of
HLM measurements being a simple procedure.
A poor correlation (r = 0.18) was found between protein content and HLM values of
oat samples. Moisture content significantly affected the HLM values of oats and results
clearly showed a decrease in HLM values with increasing moisture content. Scanning
electron microscope (SEM) micrographs revealed that the starch granules became
swollen and that they increased in size with an increase in moisture content, resulting in
a decrease in HLM. NIR hyperspectral imaging offers the testing of individual grains
non-destructively. This is often required by plant breeders because they subsequently
need to plant selected grains. NIR offers this option to plant breeders. NIR
hyperspectral imaging, which combines NIR spectroscopy with digital imaging, was
used to distinguish between six oat samples with varying HLM values. NIR
spectroscopic differences were observed between the images of the two samples with
the highest and lowest HLM values (60.2 and 49.35 kg.hL-1). Less distinct differences
were observed in the NIR hyperspectral images of two samples differing by less than
2.0 kg.hL-1. Although mixed oat samples were used, these preliminary results established the
possible use of NIR hyperspectral imaging in evaluating oat samples from breeding
trials. The use of this technique could also be extended to evaluation of other quality
characteristics of oats. / AFRIKAANSE OPSOMMING: Hektolitermassa- (HLM-)metings maak snelle en akkurate bepaling van korreldigtheid
moontlik. HLM-toestelle van verskillende lande (Australië, Kanada, Frankryk, Duitsland,
Suid-Afrika, die Verenigde Koninkryk en die Verenigde State van Amerika) is ondersoek
vir hulle uitwerking op die HLM-metings van hawer. Daarby is die potensiaal van nabyinfrarooi-
(NIR-)hiperspektrale beelding geëvalueer om tussen hawermonsters met
verskillende HLM-waardes te onderskei. Tydens vergelyking van HLM-metings verkry
van die onderskeie toestelle, het die Amerikaanse en die Suid-Afrikaanse toestelle
beduidend (P<0.05) laer HLM-waardes opgelewer in vergelyking met die ander toestelle
terwyl die Duitse toestel hoër waardes (P<0.05) as die ander toestelle getoon het. Daar
was hoë korrelasies tussen die HLM waardes verkry van die apparate met
intraklaskorrelasie (IKK) konsekwentheidwaardes van ten minste 0.90. Hierdie hoë
korrelasies sou direkte vervanging van die Suid-Afrikaanse toestel met enige van die
ander toestelle moontlik maak. Die toerusting gekies as vervanging sou ideaal gesproke
in ooreenstemming met die ISO 7971-3 standaard gekalibreer kon word (bv. die toestel
wat tans in Duitsland gebruik word).
HLM-waardes het beduidend (P<0.05) verhoog toe hawermonsters gevryf is voor
metings gemaak is, wat dui op die belang van verlengde gebruik van hierdie stap
tydens die voorbereiding van monsters. Die ondersoek na die uitwerking van die
operateur op HLM-bepalings het getoon dat die onervare operateur HLM-waardes
beduidend verskillend gemeet het teenoor dié verkry deur die ervare operateur. Dit
beklemtoon die belang van opleiding ten spyte daarvan dat HLM-metings ’n eenvoudige
prosedure is.
’n Swak korrelasie (r = 0.18) is aangetref tussen proteïeninhoud en HLM-waardes
van hawermonsters. Voginhoud het die HLM-waardes van hawer beduidend beïnvloed
en resultate het duidelik ’n styging in HLM-waardes met verhoging van die voginhoud
getoon. Aftaselektronmikroskoop- (AEM-)mikrobeelde het aangedui dat die
styselgranules swel en in grootte toeneem met verhoging van die voginhoud, wat
aanleiding gee tot ’n verlaging in HLM. NIR-hiperspektrale beelding maak die toets van
individuele korrels op niedestruktiewe wyse moontlik. Dit word dikwels deur
plantkwekers vereis aangesien hulle na toetsing uitgesoekte korrels moet plant. Nabyinfrarooi
bied hierdie opsie aan plantkwekers. NIR-hiperspektrale beelding, wat NIRspektroskopie
met digitale beelding kombineer, is gebruik om te onderskei tussen ses
hawermonsters met wisselende HLM-waardes. NIR-spektroskopiese verskille tussen die beelde van die twee monsters met die hoogste en laagste HLM-waardes (60.2 en
49.35 kg.hL-1) is waargeneem. Minder duidelike verskille is in die NIR-hiperspektrale
beelde van twee monsters wat met minder as 2.0 kg.hL-1 verskil het, waargeneem.
Alhoewel gemengde hawermonsters gebruik is, het hierdie voorlopige resultate die
moontlike gebruik van NIR-hiperspektrale beelding by die evaluering van
hawermonsters van kweekproewe vasgestel. Die gebruik van hierdie tegniek sou ook
uitgebrei kon word tot die evaluering van ander kwaliteitseienskappe van hawer.
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