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Hosseini Bai S, Darby I, Nevenimo T, Hannet G, Hannet D, Poienou M, Grant E, Brooks P, Walton D, Randall B, Wallace HM. Effects of roasting on kernel peroxide value, free fatty acid, fatty acid composition and crude protein content. PLoS One 2017; 12:e0184279. [PMID: 28902859 PMCID: PMC5597184 DOI: 10.1371/journal.pone.0184279] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 08/21/2017] [Indexed: 11/28/2022] Open
Abstract
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.
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Affiliation(s)
- Shahla Hosseini Bai
- Genecology, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland, Australia
- * E-mail:
| | - Ian Darby
- Genecology, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland, Australia
| | - Tio Nevenimo
- National Agricultural Research Institute, Islands Regional Centre – Keravat, Kokopo, East New Britain Province, Papua New Guinea
| | - Godfrey Hannet
- National Agricultural Research Institute, Islands Regional Centre – Keravat, Kokopo, East New Britain Province, Papua New Guinea
| | - Dalsie Hannet
- National Agricultural Research Institute, Islands Regional Centre – Keravat, Kokopo, East New Britain Province, Papua New Guinea
| | - Matthew Poienou
- National Agricultural Research Institute, Islands Regional Centre – Keravat, Kokopo, East New Britain Province, Papua New Guinea
| | - Elektra Grant
- Genecology, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland, Australia
| | - Peter Brooks
- Genecology, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland, Australia
| | - David Walton
- Genecology, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland, Australia
| | - Bruce Randall
- Genecology, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland, Australia
| | - Helen M. Wallace
- Genecology, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland, Australia
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Walton DA, Randall BW, Le Lagadec MD, Wallace HM. Maintaining high moisture content of macadamia nuts-in-shell during storage induces brown centres in raw kernels. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2013; 93:2953-2958. [PMID: 23471577 DOI: 10.1002/jsfa.6123] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 02/13/2013] [Accepted: 03/07/2013] [Indexed: 06/01/2023]
Abstract
BACKGROUND Kernel brown centres in macadamia are a defect causing internal discolouration of kernels. This study investigates the effect on the incidence of brown centres in raw kernel after maintaining high moisture content in macadamia nuts-in-shell stored at temperatures of 30°C, 35°C, 40°C and 45°C. RESULTS Brown centres of raw kernel increased with nuts-in-shell storage time and temperature when high moisture content was maintained by sealing in polyethylene bags. Almost all kernels developed the defect when kept at high moisture content for 5 days at 45°C, and 44% developed brown centres after only 2 days of storage at high moisture content at 45°C. This contrasted with only 0.76% when stored for 2 days at 45°C but allowed to dry in open-mesh bags. At storage temperatures below 45°C, there were fewer brown centres, but there were still significant differences between those stored at high moisture content and those allowed to dry (P < 0.05). CONCLUSION Maintenance of high moisture content during macadamia nuts-in-shell storage increases the incidence of brown centres in raw kernels and the defect increases with time and temperature. On-farm nuts-in-shell drying and storage practices should rapidly remove moisture to reduce losses. Ideally, nuts-in-shell should not be stored at high moisture content on-farm at temperatures over 30°C.
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Affiliation(s)
- David A Walton
- Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland 4558, Australia.
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Walton DA, Wallace HM. Quality changes in macadamia kernel between harvest and farm-gate. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2011; 91:480-484. [PMID: 21218481 DOI: 10.1002/jsfa.4209] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2010] [Revised: 08/12/2010] [Accepted: 10/01/2010] [Indexed: 05/30/2023]
Abstract
BACKGROUND Macadamia integrifolia, Macadamia tetraphylla and their hybrids are cultivated for their edible kernels. After harvest, nuts-in-shell are partially dried on-farm and sorted to eliminate poor-quality kernels before consignment to a processor. During these operations, kernel quality may be lost. In this study, macadamia nuts-in-shell were sampled at five points of an on-farm postharvest handling chain from dehusking to the final storage silo to assess quality loss prior to consignment. Shoulder damage, weight of pieces and unsound kernel were assessed for raw kernels, and colour, mottled colour and surface damage for roasted kernels. RESULTS Shoulder damage, weight of pieces and unsound kernel for raw kernels increased significantly between the dehusker and the final silo. Roasted kernels displayed a significant increase in dark colour, mottled colour and surface damage during on-farm handling. CONCLUSION Significant loss of macadamia kernel quality occurred on a commercial farm during sorting and storage of nuts-in-shell before nuts were consigned to a processor. Nuts-in-shell should be dried as quickly as possible and on-farm handling minimised to maintain optimum kernel quality.
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Affiliation(s)
- David A Walton
- Faculty of Science, Health and Education, University of the Sunshine Coast, Sippy Downs Drive, Sippy Downs, Queensland 4556, Australia.
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