Academic literature on the topic 'Storage of macadamia nuts'

Shelf life studies of raw Macadamia integrifolia nuts were carried out at different storage temperatures, relative humidities and time. An accelerated shelf life test was conducted, and the influence of water activity on kernel texture was studied. The antioxidants naturally present were identified by the use of thin layer chromatography. Accelerated shelf life tests showed that hydrolytic rancidity followed apparent zero order kinetics within the water activity range of 0.3 to 0.5. Oxidative rancidity measured by peroxide value appeared to follow different orders of reaction at different temperatures. At two months of storage rancidity was detected at which the headspace concentration of hexanal was 0.39 ppm and a peroxide value of 0.37 meq/kg. Headspace gas chromatography was done to find a quick and effective method for measuring oxidative rancidity. The presence of natural antioxidants was verified to explain the shelf life of macadamia nuts. In textural study, correlations were found between subjective and objective measurements. The product became unacceptable organoleptically above water activity 0.415 when stored at 20 degrees C. This level was established as the critical water activity. There is a need to establish a water activity at which the consumer is likely to reject the product.

Thesis (MSc)--Stellenbosch University, 2015.<br>ENGLISH ABSTRACT: The South African macadamia industry is centred in the sub-tropical regions of South Africa with 40% of the plantings in the Lowveld. Growers receive higher pay-outs for high kernel recovery and unblemished (not discoloured) whole kernels. It is known that the same cultivar in the Lowveld region, produces nuts that differ in kernel recovery, whole kernel recovery and kernel discolouration. Therefore to develop optimal management strategies to maximize productivity and profitability of macadamias, factors that influence kernel recovery, whole kernel recovery and kernel discolouration needed to be investigated. The fruit structures are formed the first 90 days after anthesis and the fruit continues to grow until 12 to 15 weeks after anthesis until the shell hardens. Climate, soil moisture, cross-pollination and nutrition influence this process which determines the shell thickness and kernel size which in turn both determine kernel recovery. A large set of historical data from different regions were used to establish and isolate possible factors involved in kernel recovery, whole kernel recovery and kernel discolouration. These differed between the six regions over two seasons. High kernel recovery was associated with high orchard altitude, good cross-pollination, high crop load (high yield), early season harvesting and processing of nut-in-shell (NIS), high leaf boron concentrations in Nov., water management using deficit irrigation and low daily maximum relative humidity during the nut growth stage (Oct. to middle Jan.). High whole kernel recovery was associated with high kernel recovery, early season harvesting and processing of NIS, Bungay curing system of NIS compared to ambient air, low vapour pressure deficit during the nut maturation period (middle Jan. to harvest), elevated leaf boron and copper concentrations and low manganese leaf concentrations in Nov. High crop load, no cross pollination, low leaf nitrogen and zinc and high leaf potassium concentrations in Nov. were associated with low kernel discolouration. In order to develop possible orchard practices that increase kernel recovery, whole kernel recovery and decrease kernel discolouration, two irrigation trials and one kaolin trial were conducted. In the two irrigation trials, water stress was induced over two growing seasons (2011-2013) by applying different levels of irrigation at different phenological stages. Kernel recovery was not affected by any of the treatments, but water stress could not be applied continuously due to frequent high rainfall. Moderate water stress did not influence yield, only trees that were over watered during a drier premature nut drop stage during the 2011/12 season increased yield, although it could not be repeated the following season during a wetter premature nut drop stage. In the kaolin trial, the efficacy of kaolin foliar application was evaluated to reduce heat stress. Kaolin applications did not affect kernel recovery, nut yield or quality. Temperature during the study was not continuously high (>30 ⁰C), thus heat stress could not be mitigated. We did however establish that up to five layers of foliar applied kaolin did not significantly reduce individual leaf photosynthesis.<br>AFRIKAANSE OPSOMMING: Die makadamia-industrie in Suid-Afrika, is gesentreer in die sub-tropiese streke van die land met 40% van die aanplantings in die Laeveld. Produsente ontvang hoër uitbetalings vir neute wat 'n hoë uitkraak (kernherwinning) persentasie lewer asook ongeskonde (nie verkleurde), heel-kern neute. Daar is gevind dat dieselfde kultivar verskil ten opsigte van kernherwinning, heel-kernherwinning en kernverkleuring in die Laeveld. Om 'n optimale bestuurstrategie te ontwikkel en so maksimale opbrengs en wins te verkry, moes die faktore wat kernherwinning, heel-kernherwinning en kernverkleuring beïnvloed ondersoek word. Die eerste 90 dae na blom word die vrugstrukture gevorm en vrugte groei tot en met 12 tot 15 weke na volblom totdat die dop verhard. Klimaat, grondvog, kruisbestuiwing en voedingstowwe beïnvloed die prosesse wat dopdikte en kerngrootte beïnvloed en wat beide kernherwinning bepaal. 'n Groot stel historiese data vanaf verskillende streke is gebruik om die moontlike faktore wat kernherwinning, heel-kernherwinning en kernverkleuring beïnvloed te bepaal. Hierdie aspekte het verskil in die ses streke oor twee seisoene. Hoë kernherwinning was geassosieer met hoër liggende boorde (hoogte bo see spieël), goeie kruisbestuiwing, hoë oeslading, vroeë seisoen oes en prosessering van neut-in-dop, hoë boor blaarkonsentrasie in Nov., waterbestuur met onthoudingsbesproeïng en lae daaglikse maksimum relatiewe humiditeit gedurende die neut-groei-stadium (Okt. tot middel Jan.). Hoë heel-kernherwinning was geassosieer met hoë kernherwinning, vroeë seisoen oes en prosessering van neut-in-dop, Bungay droging, lae waterdampdruk tekort gedurende die neut-rypwording stadium (Jan. tot oes), hoë boor en koper blaarkonsentrasies en lae mangaan blaarkonsentrasie in Nov. Hoë oeslading, geen kruisbestuiwing, lae stikstof, sink en hoë kalium blaarkonsentrasies in Nov. was geassosieer met lae kernverkleuring. Twee besproeïngsproewe en een kaolienproef is uitgevoer om moontlike boord praktyke te ontwikkel wat kernherwinning en heel-kernherwinning verhoog en kernverkleuring verlaag. In die twee besproeïngsproewe is watertekorte aangewend oor twee seisoene (2011-2013) deur verskillende hoeveelhede te besproei gedurende verskillende fenologiese stadiums. Kernherwinning was nie geaffekteer deur die behandelings nie, maar dit moet ingedagte gehou word dat watertekorte nie deurlopend toegepas kon word nie as gevolg van hoë reënval. Gematigde watertekorte het nie die opbrengs beïnvloed nie, slegs bome wat oor-besproei was in ’n droeër voor-rypwording-neut-val stadium in die 2011/12 seisoen het 'n verhoging in opbrengs getoon, maar dit kon nie herhaal word die daaropvolgende natter seisoen nie. In die kaolienproef, is die gebruik van kaolien blaarbespuiting geëvalueer om hitte stress te verminder. Kaolienbespuitings het geen effek op kernherwinning, neut opbrengs of neutkwaliteit gehad nie. Temperature gedurende die studie was nie deurlopend hoog nie (>30 0C) en dus kon hitte stress nie gemanipuleer word nie. Daar is wel vasgestel dat tot vyf lae kaolien nie enkel-blaar fotosintese verminder het nie.

One of the top priorities of the South African government is to maintain and enhance economic growth. The South African government is seeking to achieve this by implementing export-led growth policies. In many exporting economies. resources are scarce and often export promotion institutions face the double allocation problem. The double allocation problem implies that export promotion institutions face the difficulty of having to allocate scarce resources efficiently (Cuyvers. De Pelsmaker. Rayp & Roozen. 1995). The apportionment of financial resources is among several export promotion instruments that can be used to attain export success. In 2005. the Department of Trade and Industry (the dti). as the trade promotion organisation in South Africa. expressed the need for a scientific study on• the realistic export opportunities in products and markets. This would enable decision-makers to scientifically justify the allocation of public resources to promote products with the highest potential earnings. A Decision Support Model (DSM) designed by Cuyvers (1995) was applied to the South African economy (in a study done by Viviers & Pearson (2007)) to identify priority products with high export potential in new and I or existing markets. The DSM identified the product group,. under the Standard International Trade Classification (SITC). SITC 0577 as the twenty-second product with the most realistic export opportunities. SITC 0577 was identified as having thirty-six potential export destinations. This study evaluated each of the fifteen product categories corresponding to SITC 0577 on an HS level. to determine the product with the most potential for export success for the South African economy. This was achieved by employing a quantitative approach to construct a composite index. The composite export potential index comprised three sub indices: South Africa's export performance index. the world markets index and the production index. Based on an export potential index score of 4.16. macadamia nuts, classified under nuts not else specified (nes). were identified as the product with the highest potential for export success. Once the product with the highest export potential had been identified. trade and market access statistics were analysed to determine a target market with the highest import potential for South African macadamia nuts. Germany was selected from a group potential target markets as the target market for South African macadamia nuts based on an analysis of market size, growth trends, share in the world market trade, and market accessibility. Thereafter, a survey was conducted through unstructured telephone interviews and from secondary sources of information. The survey determined the market entry requirements, consumption trends and price information for South African exporters of macadamia nuts to Germany. This information was compiled into a market profile to provide exporters of macadamia nuts with essential market information on the German market.<br>Thesis (M.Com. (International Commerce))--North-West University, Potchefstroom Campus, 2010.

Orientador: Antonio Marsaioli Junior<br>Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos<br>Made available in DSpace on 2018-08-05T01:14:32Z (GMT). No. of bitstreams: 1 Silva_FlavioAlvesda_D.pdf: 2135599 bytes, checksum: 1cb50b2bea2c0d7059788a4f01434a15 (MD5) Previous issue date: 2005<br>Doutorado<br>Doutor em Engenharia de Alimentos

The drying of agricultural food crops is an essential process in ensuring the safe and reliable delivery of produce to consumers. This is no less true for cultivated nuts, grains and seeds, which have a certain vulnerability to degradation under moist conditions. The macadamia nut is particularly susceptible to this issue, due to its high oil content and markedly slow drying characteristics, providing rancidity and disease with an opportunity to spoil the produce. In recent decades, the design of efficient industrial drying schemes has become a large focus for researchers, with many studies aiming to better describe the underlying physical processes in food drying. This dissertation details the design and implementation of a fundamental model and accompanying simulation for the drying of nut-in-shell macadamias, intended to aid a future control system design study. Research is given toward the macadamia industry, as well as some of the relevant physical properties of the nut. An extensive review is given on modelling, with particular importance placed on techniques used for the deep-bed drying of nuts, grains and seeds. Control system architecture is briefly discussed, but is not the primary focus of this report. Verification of work done by prior researchers is carried out, before then deriving a comprehensive deep-bed drying model for macadamias. Crucial aspects toward how such a model is adapted into a MATLAB simulation is given, without intending to become an extensive review on software design. A robust and thorough model verification procedure is conducted, to prove that the final simulation does indeed successfully suit the purposes of control system design.

Saturated steam (SS) and propylene oxide (PPO) fumigation are two common methods to improve microbiological quality and safety of tree nuts. Validation of these processes is needed to ensure adequate control of bacterial pathogens. Since pathogens cannot be studied in food processing environments, surrogates with resistance comparable to the pathogens needed to be identified. The objective was to investigate the suitability of Enterococcus faecium, Pediococcus acidilactici, and Staphylococcus carnosus as surrogate bacteria for Salmonella spp. on whole cashews and macadamia nuts, processed with SS or PPO. Whole cashews and macadamia nuts were co-inoculated with a cocktail of Salmonella enterica and one of the three potential surrogates. Nuts were dried to original aw, packaged in poly-woven bags (2.3 kg) and commercially processed using vacuum assisted steam at 80 ͦ C or PPO fumigation. Salmonella and the potential surrogates were enumerated by serial dilution, and plated onto TSA with overlay of XLT-4 (Salmonella) or media selective for the potential surrogates. Mean log reductions (CFU/g) of Salmonella and each potential surrogate were compared using a paired T-test. SS results: reduction of Salmonella (6.0 ± 0.14) was significantly larger than E. faecium (4.3± 0.12), or P. acidilactici (3.7± 0.14) on whole cashews. Salmonella (5.9 ± 0.18) was significantly larger than P. acidilactici (4.4± 0.18) on whole macadamia nuts. PPO results: reduction of Salmonella (7.3 ± 0.19) was significantly greater than E. faecium (6.4± 0.31), or P. acidilactici (6.3± 0.33) on whole macadamia nuts. Reduction of Salmonella was significantly greater than E. faecium and P. acidilactici reduction on cashews. P. acidilactici may be considered a surrogate for Salmonella reduction on whole macadamia nuts and whole cashews processed using SS at 80 ͦ C. E. faecium and P. acidilactici may be considered surrogates for Salmonella reduction on whole macadamia nuts and whole cashews processed using PPO. Reduction of St. carnosus exceeded that of Salmonella indicating it is not a suitable surrogate for Salmonella using either processing intervention.<br>Master of Science in Life Sciences

Les nous pacanes són una font important d’àcids grassos mono- i poliinsaturats, fitosterols, tocoferols i compostos fenòlics. La tecnologia de polsos elèctrics (PE) s’està aplicant com a pretractament per millorar l’extracció d’oli de diferents llavors augmentant el rendiment d’extracció d’oli (REO). Aquesta tesi va demostrar que compostos fenòlics i capacitat antioxidant de les nous pacanes tenen molta relació amb l'assecat i temps d'emmagatzematge, evidenciant el seu impacte en les seves propietats funcionals. Pel que fa al tractament amb PE, la immersió de les nous en aigua per a l'aplicació de PE va disminuir el contingut inicial d'oli tant en les nous fresques com seques, demostrant que cal tenir en compte l'oli extret en l'aigua de remull. A més, l'efectivitat de la tecnologia de PE va ser depenent de la nou pacana utilitzada incrementant el REATOTAL a nou fresca però no en nou seca.<br>La almendra de nuez pecanera es una fuente importante de ácidos grasos mono- y poliinsaturados, fitoesteroles, tocoferoles y compuestos fenólicos. Una alternativa para mejorar el rendimiento de extracción de aceite total (REATOTAL) del aceite de nuez es la tecnología de campos eléctricos pulsados (CEP). En esta tesis doctoral se evidenció que tanto el contenido de compuestos fenólicos como la capacidad antioxidante de la nuez pecanera son alterados por el proceso de secado y el tiempo de almacenamiento lo que podría repercutir en las propiedades funcionales de este alimento. Respecto a la aplicación de CEP, es necesario considerar la recuperación del aceite extraído en el agua de remojo. Además, la efectividad de la tecnología de CEP fue dependiente de la nuez pecanera utilizada incrementando el REATOTAL en nuez fresca pero no en nuez seca.<br>Pecan nut kernels have been identified as an important source of mono- and polyunsaturated fatty acids, phytosterols, tocopherols, and phenolic compounds. Pulsed electric fields (PEF) are being applied as a pretreatment to improve oil extraction from different seeds increasing the oil extraction yield (OEY). This dissertation proved that phenolic compounds and antioxidant capacity of kernels are highly susceptible to drying and storage time, evidencing their impact on the functional properties of pecan nuts. Concerning pretreatment with PEF, it was demonstrated that it is necessary to take into consideration the recovery of the oil retained into the soaking water. Furthermore, the effectiveness of PEF to improve OEYTOTAL depended on whether the pretreatment was applied to fresh or dry pecan nuts, improving OEYTOTAL of fresh kernels but with no effect on OEYTOTAL of dry kernels.