Processed Foods Research Unit

Albany, CA, United States

Processed Foods Research Unit

Albany, CA, United States
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Yang J.,Northwest University, China | Yang J.,University of California at Davis | Pan Z.,University of California at Davis | Pan Z.,Processed Foods Research Unit | And 7 more authors.
Food Chemistry | Year: 2013

Infrared heating was recently used to develop a more efficient roasting technology than traditional hot air roasting. Therefore, in this study, we evaluated the shelf-life of almonds roasted with three different approaches, namely infrared (IR), sequential infrared and hot air (SIRHA) and regular hot air (HA). Nine medium roasted almond samples produced by the aforementioned heating methods were processed at three different temperatures (130, 140 and 150 °C), packed in paper bags and then stored at 37 °C for three, six or eight months. Shelf-life of the roasted almonds was determined by measuring the changes in colour, peroxide value, moisture content, water activity, volatile components and sensory quality. No significant difference was observed in moisture content and water activity among the almond samples processed with different roasting methods and stored under the same conditions. GC/MS analysis showed that aldehydes, alcohols, and pyrazines were the main volatile components of almonds. Aliphatic aldehydes such as hexanal, (E)-2-octenal, and nonanal were produced as off-odours during storage. Although the overall quality of roasted almonds produced with SIRHA and HA heating was similar during the first three months of storage, their peroxide value and concentration of aliphatic aldehydes differed significantly for different roasting methods and increased significantly in all roasted samples during storage. We postulate that hexanal and nonanal might be better indicators of the shelf life of roasted almonds than the current standard, peroxide value. © 2012 Elsevier Ltd. All rights reserved.

Milczarek R.R.,Processed Foods Research Unit | Avena-Bustillos R.J.,Processed Foods Research Unit | Peretto G.,University of Padua | Mchugh T.H.,Processed Foods Research Unit
Journal of Food Processing and Preservation | Year: 2014

Microwave (MW) almond roasting was investigated as an alternative to hot air (HA) roasting. Nonpareil almonds (Prunus dulcis) were roasted at 140C in a convection oven for different times to achieve light, medium and dark roasting levels. Several instrumental measurements were taken, establishing targets for each roasting level. To determine the MW time/power combinations necessary to match the HA targets, a response surface experiment was conducted. Additional MW-roasted samples prepared using the optimal time/power combinations underwent both instrumental and sensory analyses. The overall sensory difference test showed that, at the medium roasting level, the MW-roasted almonds were indistinguishable from their HA-roasted counterparts. At all three roasting levels, the HA- and MW-roasted samples were not significantly different in terms of sensory roasted flavor and crunchiness. Instrumental measurements supported the sensory results. When optimized, MW roasting yields results similar to HA roasting in a fraction of the time. Practical Application: The findings of this work can be used by industrial almond processors to develop large-scale microwave (MW) roasting unit operations. Also, consumers could use the optimal MW time and power combinations found in this work as guidelines for at-home preparation of roasted almonds. © 2014 Wiley Periodicals, Inc.

Paiva F.F.,Federal University of Pelotas | Paiva F.F.,Processed Foods Research Unit | Vanier N.L.,Federal University of Pelotas | Vanier N.L.,Processed Foods Research Unit | And 5 more authors.
Journal of Food Composition and Analysis | Year: 2014

Recent studies have reported the health benefits of pigmented rice cultivars due to the presence of bioactive compounds in the bran layer of caryopsis. This study evaluated the proximate composition, colour, total flavonoids, anthocyanins and proanthocyanidins contents, as well as the total phenolics and antioxidant activity of IAC-600 black rice cultivar and MPB-10 red rice lineage, as a function of degree of milling (DOM), at 0%, 4%, 7%, 10%, 12% and 15% of DOM. Black rice showed a thicker bran layer than red rice. Around 80% and 65% of the ash content of red and black rice, respectively, was distributed in the bran layer. 4% DOM reduced 47% of the fat content in red rice, while in order to reduce similar fat content in black rice, a 7% DOM was necessary. The total free phenolics were around 6- and 7-fold higher than bound phenolics for black and red rice, respectively. Although the non-milled black rice presented higher free and bound phenolics contents than non-milled red rice, the red rice showed higher DPPH and ABTS+ antioxidant activities. © 2014 Elsevier Inc.

Paraginski R.T.,Federal University of Pelotas | Vanier N.L.,Federal University of Pelotas | Vanier N.L.,Processed Foods Research Unit | Berrios J.D.J.,Processed Foods Research Unit | And 2 more authors.
Journal of Stored Products Research | Year: 2014

Maize grains are used as raw material in various food products. In countries where the production is seasonal, the grains must be stored throughout the year in order to provide sufficient maize supply for the food industries and consumers. During storage, the environmental temperature is considered as one of the most critical variables that affects grain quality. This study aimed to evaluate the effects of various storage temperatures (5, 15, 25 and 35°C) on the proximate composition, pH, fat acidity, percentage of grains infected by molds, grain color, protein solubility and pasting properties of maize stored for 12 months. Grains stored at 35°C during the 12 months period showed the greatest decrease in grain yellowness, pH, protein solubility and breakdown viscosity. An increase in disulfide bonds within the protein structure and interaction between starch and non-starch components seems to be responsible for the changes in protein solubility and pasting properties determined in maize during the storage period. Fat acidity and the percentage of grains infected by visible molds were concluded to be very dependent of moisture content. The result of this study demonstrated that the minimum temperature of 5°C was able to maintain the quality of maize stored for up 12 months. © 2014 Elsevier Ltd.

Colussi R.,Federal University of Pelotas | Pinto V.Z.,Federal University of Pelotas | Pinto V.Z.,University of Guelph | El Halal S.L.M.,Federal University of Pelotas | And 6 more authors.
Carbohydrate Polymers | Year: 2014

The high-, medium-, and low-amylose rice starches were isolated by the alkaline method and acetylated by using acetic anhydride for 10, 30, and 90 min of reaction. The degree of substitution (DS), the Fourier-transformed infrared spectroscopy (FTIR), the X-ray diffractograms, the thermal, morphological, and pasting properties, and the swelling power and solubility of native and acetylated starches were evaluated. The DS of the low-amylose rice starch was higher than the DS of the medium- and the high-amylose rice starches. The introduction of acetyl groups was confirmed by FTIR spectroscopy. The acetylation treatment reduced the crystallinity, the viscosity, the swelling power, and the solubility of rice starch; however, there was an increase in the thermal stability of rice starch modified by acetylation. © 2014 Elsevier Ltd.

Paraginski R.T.,Federal University of Pelotas | Vanier N.L.,Federal University of Pelotas | Vanier N.L.,Processed Foods Research Unit | Moomand K.,University of Guelph | And 5 more authors.
Carbohydrate Polymers | Year: 2014

Considering the importance of maize starch and the lack of knowledge about the effects of storage temperature on the isolated starch properties; maize grains were stored during 12 months at different temperatures (5, 15, 25 and 35 C). The extraction yield and the physicochemical, thermal, pasting, crystallinity and morphological properties of starches were determined. The starch isolated from grains stored at 35 C was yellowish and showed a 22.1% decrease in starch extraction yield compared to freshly harvested maize grains. At 35 C, a reduction in crystallinity was observed by the end of 12 months, despite a parallel rearrangement of the starch chains which resulted in an increase in X-ray peak intensities, gelatinisation temperatures and enthalpy. The starch isolated from maize grains stored at 35 C appears to have smaller granules, which presents some points in their surface, potentially attributed to the protein matrix compressing the granules within maize grains.© 2013 Elsevier Ltd. All rights reserved.

Klein B.,State University of Rio Grande do Sul | Klein B.,Federal University of Pelotas | Vanier N.L.,Federal University of Pelotas | Vanier N.L.,Processed Foods Research Unit | And 6 more authors.
Food Chemistry | Year: 2014

Ozone is a more powerful oxidant than common oxidising agents, such as sodium hypochlorite and hydrogen peroxide. It is considered as a safer starch modification method for both consumers and the environment. However, few studies have investigated the changes in starch properties associated with ozone treatment, particularly when applied in aqueous solution. This work aimed to evaluate the carbonyl and carboxyl contents, the X-ray diffraction patterns, the spectrum profiles of Fourier transform infrared spectroscopy, the pasting properties and the surface morphology of ozone-oxidised cassava starch during 60 min under different pH (3.5, 6.5 and 9.5) at 25 C. The pH 6.5 and 9.5 seemed to favour the cross-linking between the depolymerised starch molecules during ozonation. The pH 3.5 was more effective in reducing the peak viscosity, breakdown, setback and final viscosity of cassava starch during ozonation in aqueous solution. No differences in the granule surface morphology were observed in the ozone-treated cassava starches compared to native starch. © 2014 Elsevier Ltd. All rights reserved.

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