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Article
Publication date: 2 October 2019

Oluseyi Moses Ajayi, Wayne Martindale and Mark Swainson

The purpose of this paper is twofold: first, it aims to investigate how salt and sugar reduction in foods due to the pressure from the emerging food regulations will…

Abstract

Purpose

The purpose of this paper is twofold: first, it aims to investigate how salt and sugar reduction in foods due to the pressure from the emerging food regulations will affect the physico-electrical properties (PEPs) of orange juice and tomatoes during a selected PEP-dependent thermal processing. Second, the authors are keen to understand how variations in salt and sugar ingredients will affect the time-temperature processing requirements.

Design/methodology/approach

PEPs of the samples (orange juice and tomatoes) were measured using the KD2 thermal analyser and RS conductivity metre. Both samples with varying salt and sugar levels were subjected to ohmic heating processing using a 10 kW ohmic heater. Dehydration rates and processing times for pasteurisation were obtained.

Findings

Electrical conductivity increases with added salt in tomato puree but decreases with added sugar in orange juice. Statistical evidence confirmed significant changes in heating rates and processing times of tomatoes and orange juice as their relevant salt and sugar levels change. Reduction in salt content in tomato puree led to increase in time and energy for the thermal processes. While reduction in added sugar in orange juice results led to reduction in processing time and energy requirement for the processing operation.

Research limitations/implications

The study is limited to small change in salt and sugar variations in order to reflect recommended limits. There were therefore no significant changes in thermal conductivity for the range investigated. Also this study is focussed on two food products.

Practical implications

Current pressure on the need to reduce salt and sugar in foods necessitates research to increase food processing industry insight into the process and product impacts of such recipe changes, with particular regard to processing efficiency and product safety and quality.

Originality/value

This study represents an attempt to understand the impact of salt and sugar variations on properties and processing requirements of tomato puree and orange juice.

Details

British Food Journal, vol. 122 no. 1
Type: Research Article
ISSN: 0007-070X

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Article
Publication date: 19 April 2011

Frederick T. Tabit and Elna M. Buys

The presence of Bacillus sporothermodurans in retail UHT milk along with milk from different points of a processing line was determined. This paper aims to investigate the…

Abstract

Purpose

The presence of Bacillus sporothermodurans in retail UHT milk along with milk from different points of a processing line was determined. This paper aims to investigate the effect of chilling, pre‐heating, UHT, reprocessing and H2O2 individually and in combination on the survival of B. sporothermodurans in broth.

Design/methodology/approach

Standard plate counts were conducted for all milk samples and isolates from UHT milk were characterised using PCR. BS vegetative cells and spores in broth were subjected to various stresses encountered, during UHT processing of milk. Survival counts were conducted after all treatments.

Findings

B. sporothermodurans was detected in retail UHT milk packs from only one processor. UHT treatment at 140°C for 4s eliminated B. sporothermodurans in broth. The combination of chilling and UHT was more effective in eliminating B. sporothermodurans spores than UHT treatment alone. H2O2 was also effective in eliminating B. sporothermodurans spores after 15 min of exposure. The adopted real time (RT) PCR with SYBR Green method was effective for the confirmation of B. sporothermodurans.

Originality/value

This research is the first to be conducted with regards to the detection of B. sporothermodurans in UHT milk in South Africa and determining the effect of UHT processing stresses on their survival. These results can be used to design processing parameters so as to effectively eliminate B. sporothermodurans spores during UHT processing. This research is the first in which RT PCR with SYBR Green has been used to characterise B. sporothermodurans.

Details

British Food Journal, vol. 113 no. 4
Type: Research Article
ISSN: 0007-070X

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Article
Publication date: 26 August 2021

Hong-Chuong Tran, Yu-Lung Lo, Trong-Nhan Le, Alan Kin-Tak Lau and Hong-You Lin

Depending on an experimental approach to find optimal parameters for producing fully dense (relative density > 99%) Inconel 718 (IN718) components in the selective laser…

Abstract

Purpose

Depending on an experimental approach to find optimal parameters for producing fully dense (relative density > 99%) Inconel 718 (IN718) components in the selective laser melting (SLM) process is expensive and offers no guarantee of success. Accordingly, this study aims to propose a multi-scale simulation framework to guide the choice of processing parameters in a more pragmatic manner.

Design/methodology/approach

In the proposed approach, a powder layer, ray tracing and heat transfer simulation models are used to calculate the melt pool dimensions and evaporation volume corresponding to a small number of laser power and scanning speed conditions within the input design space. A layer-heating model is then used to determine the inter-layer idle time required to maximize the temperature convergence rate of the solidified layer beneath the power bed. The simulation results are used to train surrogate models to construct SLM process maps for 3,600 pairs of the laser power and scanning speed within the input design space given three different values of the underlying solidified layer temperature (i.e., 353 K, 673 K and 873 K). The ideal selection of laser power and scanning speed of each process map is chosen based on four quality-related criteria listed as follows: without the appearance of key-hole melting; an evaporation volume less than the volume of the d90 powder particles; ensuring the stability of single scan tracks; and avoiding a weak contact between the melt pool and substrate. Finally, the optimal laser power and scanning speed parameters for the SLM process are determined by superimposing the optimal regions of the individual process maps.

Findings

The feasibility of the proposed approach is demonstrated by fabricating IN718 test specimens using the optimal processing conditions identified by the simulation framework. It is shown that the maximum density of the fabricated parts is 99.94%, while the average density is 99.88% and the standard deviation is less than 0.05%.

Originality/value

The present study proposed a multi-scale simulation model which can efficiently predict the optimal processing conditions for producing fully dense components in the SLM process. If the geometry of the three-dimensional printed part is changed or the machine and powder material is altered, users can use the proposed method for predicting the processing conditions that can produce the high-density part.

Details

Rapid Prototyping Journal, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 28 June 2021

Pradeep Kumar Mishra, Senthil Ponnusamy and Mohan Satyanarayana Reddy Nallamilli

The purpose of this paper is to analyse the effect of water absorption and heat treatment on the impact strength of three-dimensional (3D) printed Izod specimens. A…

Abstract

Purpose

The purpose of this paper is to analyse the effect of water absorption and heat treatment on the impact strength of three-dimensional (3D) printed Izod specimens. A low-cost post-processing technique is proposed to improve the impact strength of 3D printed parts substantially.

Design/methodology/approach

In the present work, the effect of water absorption and the heat-treatment on the impact resistance of 3D printed poly-lactic acid parts possessing different layer-height, build-orientation and raster-orientation was studied. Water absorption tests were conducted in distilled water and it was observed that the water- absorption in specimens follows the Fickian diffusion mechanism. A set of specimens was heat-treated at 120°C for 1 h using an induction furnace. Post water absorption and heat-treatment a significant increase in the impact resistance is noticed and especially a steep increase in impact resistance is observed in heat-treated specimens.

Findings

Experimental findings show that raster orientation played a major role in the impact resistance of a 3D printed structure in comparison to other process parameters. The order of influence of process parameters on the impact strength of specimens was disclosed by the mean effect plots. In terms of processing time and cost, the post-processing heat-treatment approach was found to be convenient compared to the water absorption technique.

Originality/value

This paper presents a new set of low-cost post-processing techniques (water-absorption and heat-treatment) for improving the impact strength of 3D printed specimens.

Details

Rapid Prototyping Journal, vol. 27 no. 6
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 1 August 1998

Jaroslav Mackerle

This paper gives a review of the finite element techniques (FE) applied in the area of material processing. The latest trends in metal forming, non‐metal forming, powder…

Abstract

This paper gives a review of the finite element techniques (FE) applied in the area of material processing. The latest trends in metal forming, non‐metal forming, powder metallurgy and composite material processing are briefly discussed. The range of applications of finite elements on these subjects is extremely wide and cannot be presented in a single paper; therefore the aim of the paper is to give FE researchers/users only an encyclopaedic view of the different possibilities that exist today in the various fields mentioned above. An appendix included at the end of the paper presents a bibliography on finite element applications in material processing for 1994‐1996, where 1,370 references are listed. This bibliography is an updating of the paper written by Brannberg and Mackerle which has been published in Engineering Computations, Vol. 11 No. 5, 1994, pp. 413‐55.

Details

Engineering Computations, vol. 15 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 1 May 1994

N. Brännberg and J. Mackerle

This paper gives a review of the finite element techniques (FE)applied in the area of material processing. The latest trends in metalforming, non‐metal forming and powder…

Abstract

This paper gives a review of the finite element techniques (FE) applied in the area of material processing. The latest trends in metal forming, non‐metal forming and powder metallurgy are briefly discussed. The range of applications of finite elements on the subjects is extremely wide and cannot be presented in a single paper; therefore the aim of the paper is to give FE users only an encyclopaedic view of the different possibilities that exist today in the various fields mentioned above. An appendix included at the end of the paper presents a bibliography on finite element applications in material processing for the last five years, and more than 1100 references are listed.

Details

Engineering Computations, vol. 11 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 1 January 1992

John Driscoll

Highlights the lack of detailed published information on the use ofinfra‐red heating in food processing in the UK. Provides a number ofanswers based on conclusions from a…

Abstract

Highlights the lack of detailed published information on the use of infra‐red heating in food processing in the UK. Provides a number of answers based on conclusions from a recent seminar. These are a reluctance of users to reveal information to their competitors of where it is used, perceived technical problems (some infra‐red heaters contain glass) and fears on energy costs which restrict its wider use and lack of knowledge of the technology by food processing plant manufacturers. Discusses the attributes of infra‐red heating and gives some examples of its use (not all in the UK) for food processing.

Details

Nutrition & Food Science, vol. 92 no. 1
Type: Research Article
ISSN: 0034-6659

Keywords

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Article
Publication date: 1 May 1995

Christopher K. Hess and Ioannis N. Miaoulis

During the thermal processing of thin films in which low intensity lineheat sources are used, extended processing times are often required to reachsteady state (˜15 sec)…

Abstract

During the thermal processing of thin films in which low intensity line heat sources are used, extended processing times are often required to reach steady state (˜15 sec). In addition, the melting of the film may occur some time after processing has begun, and therefore there is no initial melting condition within the film. In such cases, computer simulations may become very time consuming, and the development of an efficient computational method which incorporates the initial formation of the melt during processing is necessary. A general technique was developed to accurately model two‐dimensional heat conduction in a multilayer film structure with one‐dimensional phase change in one of the thin films. These conditions frequently exist in thin film thermal processing when the thermal gradient through the thickness of the melting film can be considered negligible. The method involves an implicit formulation of the modified enthalpy method. The solid/liquid interface energy‐balance equation is taken into account which allows the exact location of the interface to be tracked within a control volume. A comparison is made between the explicit and implicit modified methods to test efficiency and accuracy. The implicit method is then applied to the zone‐melting recrystallization of a silicon thin film in a multilayer structure.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 5 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 20 March 2017

Michele Chiumenti, Xin Lin, Miguel Cervera, Wei Lei, Yuxiang Zheng and Weidong Huang

This paper aims to address the numerical simulation of additive manufacturing (AM) processes. The numerical results are compared with the experimental campaign carried out…

Abstract

Purpose

This paper aims to address the numerical simulation of additive manufacturing (AM) processes. The numerical results are compared with the experimental campaign carried out at State Key Laboratory of Solidification Processing laboratories, where a laser solid forming machine, also referred to as laser engineered net shaping, is used to fabricate metal parts directly from computer-aided design models. Ti-6Al-4V metal powder is injected into the molten pool created by a focused, high-energy laser beam and a layer of added material is sinterized according to the laser scanning pattern specified by the user.

Design/methodology/approach

The numerical model adopts an apropos finite element (FE) activation technology, which reproduces the same scanning pattern set for the numerical control system of the AM machine. This consists of a complex sequence of polylines, used to define the contour of the component, and hatches patterns to fill the inner section. The full sequence is given through the common layer interface format, a standard format for different manufacturing processes such as rapid prototyping, shape metal deposition or machining processes, among others. The result is a layer-by-layer metal deposition which can be used to build-up complex structures for components such as turbine blades, aircraft stiffeners, cooling systems or medical implants, among others.

Findings

Ad hoc FE framework for the numerical simulation of the AM process by metal deposition is introduced. Description of the calibration procedure adopted is presented.

Originality/value

The objectives of this paper are twofold: firstly, this work is intended to calibrate the software for the numerical simulation of the AM process, to achieve high accuracy. Secondly, the sensitivity of the numerical model to the process parameters and modeling data is analyzed.

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Article
Publication date: 14 May 2018

Srinivasan Raghavan, Mui Ling Sharon Nai, Pan Wang, Wai Jack Sin, Tao Li and Jun Wei

The paper presents a wide range of post processing heat treatment cycles performed to Electron Beam Melted (EBM) Ti6Al4V alloy and establishes correlations of heat treat…

Abstract

Purpose

The paper presents a wide range of post processing heat treatment cycles performed to Electron Beam Melted (EBM) Ti6Al4V alloy and establishes correlations of heat treat process to microstructure and mechanical property (microhardness). The research also identifies the optimal heat treatment to obtain the best microstructure and mechanical properties (hardness and tensile).

Design/methodology/approach

Rectangular bars fabricated using EBM was used to study the different heat treatment cycles. A variety of heat treatments from sub ß-transus, super ß-transus, near ß-transus and solution aircool plus ageing were designed. After the heat treatment process, the samples were analysed for, α lath width, prior ß grain size, microhardness and nanohardness. Tensile tests were done for the heat treated samples showing most refined α lath structure with uniform globular grains.

Findings

A clear correlation was observed between α lath width and the microhardness values. The solution aircooled plus aged samples exhibited the best refinement in α-ß morphology with uniform equiaxed grains. The tensile properties of the solution aircooled plus aged samples were comparable to that of the EBM printed samples and better than ASTMF1472 specifications.

Originality/value

There is hardly any prior work related to post processing heat treatment of EBM built Ti6Al4V other than HIP treatments. The variety of heat treatment cycles and its influence in microstructure and properties, studied in this research, gives a clear understanding on how to tailor final microstructures and select the optimal heat treatment process.

Details

Rapid Prototyping Journal, vol. 24 no. 4
Type: Research Article
ISSN: 1355-2546

Keywords

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