The aim of this research was to study the effect of pulsed electric fields (PEF) on the microstructure of “kumara” sweet potato (Ipomoea batatas cv. Owairaka) and its quality after frying. Whole ...sweet potato tubers were treated at different electric field strengths ranging from 0.3 to 1.2kV/cm with specific energy levels between 0.5 and 22kJ/kg. Cell viability was determined using tetrazolium staining to investigate the uniformity of the PEF effect across tubers. Based on the patterns of viable cells it was observed that the effect of PEF was not homogeneous across the tuber. This result was also supported by the pattern of enzymatic browning due to PEF facilitating the reaction of polyphenoloxidase and phenols. PEF treatment resulted in significant softening of the ground tissues, but not on the dermal tissues, as determined by texture analysis. With respect to frying quality, tubers pre-treated with PEF at electric field strength of 1.2kV/cm and fried at 190°C had an 18% lower oil content than non-PEF treated samples. The kinetics of browning as a function of frying time could be described by a fractional conversion model. The activation energy (Ea) of the browning rate during frying increased (more temperature sensitive) due to PEF pretreatment at 0.5kV/cm and 1.2kV/cm. It implies that PEF pretreatment allows frying the potato chips at lower temperature in order to achieve the same brown colour intensity as the non-PEF treated tubers. This study shows clearly that PEF could reduce the energy required for cutting and frying of kumara.
This study provides evidence that the effect of PEF processing on whole kumara tubers is not uniform, demonstrating heterogenous distribution. These findings provide important information for food industry to design appropriate PEF processing conditions for solid materials. More importantly, PEF treatment reduced the energy required for cutting and frying of kumara, and reduced the oil content in the fried kumara chips.
•PEF induced cell electroporation is not homogenous across the whole sweet potato tuber.•Softening due to PEF was more pronounced on the flesh than on the skin.•PEF treatment prior to frying reduced the oil content of fried sweet potato chips.•PEF reduced the temperature dependence of the darkening rate of sweet potato chips during frying.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Hard mineral clast sediments applied to dry archaeological fields in the distant apical islands of the Polynesian triangle are frequently associated with sweet potato / kūmara (Ipomoea batatas (L) ...Lam.) cultivation. In a novel variation on this practice, north-western South Island Māori deposited tuangi (Austrovenus stutchburyi (Wood, 1828)) mollusc beach valves to cap 10–20 cm deep planting holes or pits by or around the sixteenth century AD at Triangle Flat, Golden Bay. Discrete tuangi beach valve sediment had been extended over much of the larger field surface in association with shallow (<10 cm deep) planting depressions. Surface shell deposits would have suppressed weed growth, redirected radiant energy onto young kūmara plants, and conserved planting pit soil and moisture against disruptive and desiccating winds, respectively. The temporal extension of Triangle Flat shell sediment could be related to socio-economic and political pressures to improve kūmara production from a fixed land unit. However, since climate change beginning in the sixteenth century brought cooler temperatures and eventually, stronger westerly winds to this region, it seems more likely that shell mulch was extended to maintain shallow planting soils and production in a colder, windier period. This local, kūmara-focused development may have been encouraged by the opportunity to apply ritually safe and perhaps spiritually potent, uncooked tuangi beach shell to tapu cultivation surfaces.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NMLJ, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
Sweet potato (kumara) tubers of differing colours (orange, red and white) were used to produce tuber flour, a purified starch fraction and an isolated fibre extract. The fractions from each tuber ...colour were added into a biscuit mixture, and the effects of tuber source and fraction composition were observed in relation to the physico-chemical characteristics of biscuits. Addition of sweet potato flour and fibre fractions to white wheat flour significantly reduced the pasting properties (peak and final viscosity) of the resulting gels by up to seven-fold compared with the control wheat flour gel (as determined by the Rapid Visco Analyser). The addition of sweet potato starch affected the pasting properties of wheat flour-sweet potato starch mixes to a lesser extent. Biscuit texture (force required to cause a biscuit to fracture) was significantly reduced with the incorporation of sweet potato fibre into the biscuit dough preparation, this was linked to a reduction in biscuit thickness and spread ratio. However, the addition of sweet potato flour and starch resulted in biscuits of similar firmness as the control biscuits.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Evaluated soft rot disease development in sweet potato storage roots of different cultivars, using varying wounding methods. Source: National Library of New Zealand Te Puna Matauranga o Aotearoa, ...licensed by the Department of Internal Affairs for re-use under the Creative Commons Attribution 3.0 New Zealand Licence.
Distant but cognate, pre-contact southern Polynesians created extensive rocky cultivation sediments and soils. This early agronomy is evaluated as evidence of innovation or diffusion associated with ...South American sweet potato (kumara) introductions. For South Island Maori, soil temperatures and drainage were improved in kumara cultivation under and within transported gravel and sand deposits. On Rapa Nui/Easter Island, rocky sediment was spread over cultivation fields to conserve soil and moisture against desiccating winds. While there is overlap in lithic sediment, anthrosol thickness and size classes from both distant islands, the evidence of discrete physical properties and environments is more consistent with innovation. On Rapa Nui, low-elevation lithic cultivation has continued to the present. Extensive northern South Island lithic fields were abandoned before the nineteenth century ad, perhaps because of social disruption or climate change.
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BFBNIB, DOBA, INZLJ, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK, ZRSKP
Although originally domesticated in tropical America, the sweetpotato Ipomoea batatas (L.) Lam. has a long history of cultivation in the Pacific region. While the post-Columbus dispersal of ...sweetpotato to Asia and the Pacific is well documented, the hypothesis that there was a prehistoric transfer of sweetpotato by Peruvian or Polynesian voyagers from Peru to Oceania has long been a controversial issue. The objective of this study was to assess the genetic diversity and interrelationships of sweetpotato landraces from the Pacific region and Latin America, and test the hypothesis of human transfer of this crop to the Pacific Island in prehistoric times. Seventy-five sweetpotato landraces from Peru, Ecuador, Mexico, the Philippines, Papua New Guinea (PNG) and 5 Oceania countries were analyzed using amplified fragment length polymorphism (AFLP). Multidimensional scaling (MDS) and analysis of molecular variance (AMOVA) revealed a large genetic variation in the Oceania gene pool, far greater than that in Peru-Ecuador. The Mexican cultivars were grouped together with those of Oceania. In contrast, there is little association between the Peru-Ecuador germplasm and that of Oceania. These results suggest that Peru-Ecuador may not be the source of the Oceania sweetpotato germplasm. Natural dispersal from Mesoamerica is an alternative explanation, to the ‘Kumara hypothesis’, for the origin of the Oceania sweetpotato.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Confirms sweetpotato (kumara) growers' field observations that populations of paraquat-resistant solanaceous weeds are now common, identifying them as Solanum nigrum L and Solanum americanum Mill. ...Explores the relationship between paraquat application rates and plant responses for Solanum weed populations derived from commercial sweetpotato fields. Source: National Library of New Zealand Te Puna Matauranga o Aotearoa, licensed by the Department of Internal Affairs for re-use under the Creative Commons Attribution 3.0 New Zealand Licence.
Malloy examines what role should a company play in a national crisis. Sahan Kumara couldn't believe what he was seeing online. Two hours earlier, a tsunami had hit Indonesia, sending a wall of water ...gushing through resorts, sweeping away villages, flooding fields, and killing thousands. Now the waves had struck the coast of his own island nation, causing similar devastation. Monitoring the reports from his office in the capital, miles away from the disaster zone, Sahan was safe. But he knew that a great many others were not--including employees and customers of the Kumara Group, his family's business
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IZUM, KILJ, NUK, PILJ, SAZU, UL, UM, UPUK
After the conflict ended in May 2009, the Yal Devi recommenced operations to Thandikulam on June 6, 2009 and then extended its run to Omanthai on May 29 of 2011. It commenced services to Kilinochchi ...in September 2013 and extended the service to Pallai in March this year.
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