Presence Of Testa Research Articles

Presence of Testa and Shell Maintains Oil Stability in Almond and Canarium Nuts

(1) Background: The oil stability of tree nuts during storage can be influenced by storage conditions such as temperature, humidity, and moisture concentration. However, few studies have assessed how the presence of testa and shell affects the oil stability of tree nuts during storage. We aimed to determine how storage conditions affect oil stability in almond and canarium, in particular, the presence of testa and storage time of nut-in-shell (NIS). (2) Methods: We measured peroxide value (PV), free fatty acid (FFA) and hexanal concentrations of almond and canarium (blanched vs. kernel-in-testa) stored at 45 °C for 24 days. We also measured PV, FFA and fatty acid composition of canarium samples at days 0 and 140 stored as NIS under ambient conditions. (3) Results: The presence of testa in almond and canarium decreased hexanal and PV concentrations at day 24 of incubation. Canarium PV and FFA concentrations increased over 140 days of storage in the shell compared to day 0. However, both PV and FFA concentrations remained within the acceptable threshold during storage. No changes in fatty acid composition were found during NIS storage. (4) Conclusions: Testa and shell could act as a natural coating, slowing down oxidation rates. Hence, long-term storage on nuts in testa or nuts in shell are recommended for tree nuts.

Effects of roasting on kernel peroxide value, free fatty acid, fatty acid composition and crude protein content.

Roasting nuts may alter their chemical composition leading to changes in their health benefits. However, the presence of testa may alleviate the negative effects of thermal treatments. Hence, this study aimed to explore the effects of roasting on kernel chemical quality and colour development of Canarium indicum and examine to what extent testa would protect kernels against damage from roasting. Roasting decreased peroxide value but increased free fatty acid, probably due to increased cell destruction and lack of enzyme inactivation, respectively. Protein content of kernels significantly decreased after roasting compared to raw kernels. However, testa-on kernels contained significantly higher protein content compared to testa-off kernels. Whilst colour development and mottling were observed in temperatures beyond 120°C, roasting did not alter fatty acid compositions of kernels. The mild roasting and presence of testa in kernels can be used to enhance health benefits of kernels.

Development of a database on the quality attributes of released improved sorghum varieties and cultivars in southern Africa

The need for increased sorghum utilisation in southern Africa was noted by the South African Sorghum Section 7 Committee (2007). It recommended the use of improved sorghum varieties and cultivars to ensure high yield and better grain quality attributes. However, the adoption rate of the available improved sorghum varieties and cultivars in southern Africa is very low (Chisi 2003). This is due to a lack of adequate information and dissemination (Heinrich & Mgonja 2002) both to producers and processors. This study focused on the development of a database on the quality attributes of improved sorghum varieties and cultivars, in order to boost sorghum utilisation. A list of the released and available improved sorghum varieties and cultivars was compiled for eight countries in southern Africa. The information database spreadsheets developed contain the following information: cultivar yield potentials; agronomic and production requirements; plant and grain quality traits; end-use application with reference to malting and brewing quality attributes. Grain quality information provided: grain size, glume colour and traits, grain colour, 1000 kernel weight, percent floaters, dehulling loss, grain texture, milling yield, water absorption, Agtron reflectance value (wet/dry), flour colour, testa presence or absence, and tannin content. The information was gathered from various sources, including existing databases and research data. Nineteen open-pollinating-varieties (OPV) and 45 hybrid (H) cultivars of improved sorghum are available in southern Africa. Sixteen of these improved sorghums are white tan-plant type, while others are red and purple plant type. The grain yield potentials show significant improvement compared to the traditional landraces. Most of these improved sorghums have wide adaptability, resistance to diseases and are drought tolerant. The OPVs have early to medium maturity, while Hs are medium to late maturity. The high tannin cultivars (type III) are mostly Hs. The majority of these improved sorghums are characterised by having uniform grain size and intermediate to corneous endosperm texture. The available grain quality information is limited to milling quality. Malting quality attribute information is available only for few Hs.The high grain yield potentials of the improved sorghum varieties and cultivars can improve the level of sorghum production in southern Africa. Despite the available grain quality information being limited, it can be applied to a certain extent particularly with respect to malting and brewing quality. More complete quality characterisation is necessary, to help sorghum producers and end-users in southern Africa. The database has now been posted on the International Sorghum and Millet Collaborative Research Support Program (INTSORMIL) website (www.intsormil.org).