Influence of different extraction parameters on a solid-phase dynamic extraction for the gas chromatographic determination of d-limonene degradation products by using a fractional factorial design.

Through the application of a solid-phase dynamic extraction (SPDE) method for the determination of volatile substances, different parameters may influence the extraction and desorption process and are, therefore, vital for the determination of the extracted substances via gas chromatography (GC). In this study, the influence of extraction und desorption parameters of an SPDE-GC method for the determination of the d-limonene degradation products, namely, alpha-terpineol, (-)-carveol, and (S)-carvone, in an aqueous model system was evaluated using a factorial fractional design. The aim was to reduce the number of factors that should be considered for the optimization of an SPDE procedure for different applications. It could be shown that the extraction efficiency of alpha-terpineol, (-)-carveol, and (S)-carvone is significantly influenced by the extraction parameters incubation temperature, number of extraction strokes, and amount of added NaCl. All 3 parameters have a positive effect on the extraction and determination of the examined d-limonene degradation products. Due to the identification of significant factors on the basis of an experimental design, the results of this study can be very useful for further development of SPDE methods for different applications.

Identification of lactic acid bacteria isolated from kimchi and studies on their suitability for application as starter culture in the production of fermented sausages.

The aim of the investigation was to identify strains of lactobacilli coming from kimchi with properties suitable for use as starter cultures in sausage fermentation. A total of 31 strains of lactobacilli were isolated from kimchi on the 4-6th day of fermentation at 20°C using MRS agar plates and identified on the basis of morphological, biochemical, and physiological characteristics. The isolates were identified as Leuconostoc mes.mes./dent (12.9%), Lactobacillus curvatus (9.7%), Lactobacillus brevis (35.5%), Lactobacillus sake (25.8%), and Lactobacillus plantarum (16.1%). Thus, 51.6% of the isolates were homo-fermentative or facultative hetero-fermentative bacteria and the rest (48.4%) were hetero-fermentative bacteria. Among them L. brevis, L. curvatus, L. plantarum, and L. sake were investigated for their growth profile and metabolism characteristics in the fluid (submerged) model-medium modified according to the special conditions of fermented sausages. Relatively good growth properties were found for L. brevis, L. plantarum, and L. sake with maximum numbers of 8.18, 8.51 and 8.17cfu/ml, respectively, whereas L. curvatus could not adapt to the special environmental conditions. Regarding souring properties, L. brevis showed little ability to decrease pH, whereas L. curvatus, L. plantarum, and L. sake showed relatively good acidifying properties. According to the results of glucose fermentation and its products, only L. plantarum exhibited homo-fermentative characteristics. As a result only L. plantarum among the isolates from kimchi had an ability to adapt to the complex environment of fermented sausage, which will thereby allow them to act as starter cultures and natural preservatives in sausage production.

The antioxidant properties of baechu-kimchi and freeze-dried kimchi-powder in fermented sausages.

The antioxidant properties of baechu-kimchi in fermented sausages were evaluated by investigating its effect on the changes in total free fatty acid content, peroxide value, and TBARS during ripening. The conditions for its antioxidant effectiveness were optimized in a model system (beaker sausages). For this, the conditions of added kimchi - form (kimchi and freeze-dried kimchi-powder), fermentation temperature (7 and 20 °C) and concentrations (5%, 10% and 15%) - were varied. The results were compared with that of the control without kimchi. According to the evolution of peroxide value and TBARS, the addition of 5% and 10% kimchi clearly indicated retardation of the development of lipid oxidation. However, an increase in the amount of kimchi added caused a prooxidant effect. The antioxidant effect of kimchi has been found to be dependant on its fermentation temperature as the batches treated with kimchi fermented at 20 °C displayed better protection against the formation of oxidative products than those fermented at 7 °C. Kimchi-powder did not show any antioxidant properties.

Transformation of vegetable waste into value added products: (A) the upgrading concept; (B) practical implementations.

Waste can contain many reusable substances of high value. Depending on there being an adequate technology this residual matter can be converted into commercial products either as raw material for secondary processes, as operating supplies or as ingredients of new products. Numerous valuable substances in food production are suitable for separation and recycling at the end of their life cycle, even though present separation and recycling processes are not absolutely cost efficient. In Part A a need statement is visualised--based on a holistic concept of food production--for the vegetable industry, recording occurrence, quantities and utilisation of the residual products. A literature survey, covering more than 160 articles from all over the world, plus our own investigations summarises the latest knowledge in the above-mentioned field and outline prospects for future economic treatment of vegetable 'co-products'. The main goal of a clean production process is demonstrated by three practical implementations in Part B: 1. Upgrading of vegetable residues for the production of novel types of products: multifunctional food ingredients in fruit juice and bakery goods. 2. Bioconversion via solid-state fermentation: vegetable residues as an exclusive substrate for the generation of fruity food flavours. 3. Conversion of vegetable residues into operating supplies: bioadsorbents for waste water treatment. The investigations are promising with regard to future application in the mentioned industrial branch. The outlined concept can be naturally transferred to several areas of industrial food production. The intentions of this research area are located at the development of techniques, which fulfil the conditions of environmental protection with costs to a minimum. The prospect of several new niche markets is worthwhile indeed.

Polymer incompatibility as a potential tool for polyphenol recovery from olive mill wastewater.

Experiments were designed and preformed in consideration of polymer type (proteins, i.e. caseinate and ovalbumin, and polysaccharides, i.e. alginate and methylcellulose), charge character and polysaccharide concentrations, intended to understand how the polymer properties determine both phase separation and polyphenol partitioning from olive mill wastewater (OMW). The highest yield of polyphenols (YBP=92.9%) was achieved in an aqueous two-phase system (ATPS) using an ovalbumin-methylcellulose system (OMCS) in comparison to ATPS with caseinate-alginate system (CAS; YBP=85.8%) or caseinate methylcellulose system (CMCS; YBP=74%). The performance of CMCS for the ATPS partitioning of polyphenols in OMW was found to depend on the addition of salt (sodium chloride). The use of centrifugation as assistive technology appears to be necessary for the polyphenol partitioning in ATPS using OMCS. In contrast to these polymer systems, CAS caused a rapid ATPS without resorting to centrifugation and salt, mainly because of strong electrostatic repulsion between alginate and caseinate. In this regard, CAS in phase-separated OMW obtained a partition coefficient of protein (KP1) of 0.04, a tie-line length (TLL) of 10.47% (w/w) and a phase volume ratio (VR) of 0.7. Thus, ATPS based on CAS represent an efficient and environmentally friendly concept in recovery of polyphenols from OMW. The spray drying of the caseinate-polyphenol-rich phase from CAS could become a dry intermediate product with potential use in the food and non-food industry.

Prediction of dynamic metabolic behavior of Pediococcus pentosaceus producing lactic acid from lignocellulosic sugars.

A dynamic metabolic model is presented for Pediococcus pentosaceus producing lactic acid from lignocellulose-derived mixed sugars including glucose, mannose, galactose, arabinose, and xylose. Depending on the pairs of mixed sugars, P. pentosaceus exhibits diverse (i.e., sequential, simultaneous or mixed) consumption patterns. This regulatory behavior of P. pentosaceus is portrayed using the hybrid cybernetic model (HCM) framework which views elementary modes of the network as metabolic options dynamically modulated. Comprehensive data are collected for model identification and validation through fermentation experiments involving single substrates and various combinations of mixed sugars. Most sugars are metabolized rather sequentially while co-consumption of galactose and arabinose is observed. It is demonstrated that the developed HCM successfully predicts mixed sugar data based on the parameters identified mostly from single substrate data only. Further, we discuss the potential of HCMs as a tool for predicting intracellular flux distribution with comparison with flux balance analysis.

Modeling of an integrated fermentation/membrane extraction process for the production of 2-phenylethanol and 2-phenylethylacetate.

An unstructured model for an integrated fermentation/membrane extraction process for the production of the aroma compounds 2-phenylethanol and 2-phenylethylacetate by Kluyveromyces marxianus CBS 600 was developed. The extent to which this model, based only on data from the conventional fermentation and separation processes, provided an estimation of the integrated process was evaluated. The effect of product inhibition on specific growth rate and on biomass yield by both aroma compounds was approximated by multivariate regression. Simulations of the respective submodels for fermentation and the separation process matched well with experimental results. With respect to the in situ product removal (ISPR) process, the effect of reduced product inhibition due to product removal on specific growth rate and biomass yield was predicted adequately by the model simulations. Overall product yields were increased considerably in this process (4.0 g/L 2-PE+2-PEA vs. 1.4 g/L in conventional fermentation) and were even higher than predicted by the model. To describe the effect of product concentration on product formation itself, the model was extended using results from the conventional and the ISPR process, thus agreement between model and experimental data improved notably. Therefore, this model can be a useful tool for the development and optimization of an efficient integrated bioprocess.

Microencapsulation of fish oil by spray granulation and fluid bed film coating.

The stability of microencapsulated fish oil prepared with 2 production processes, spray granulation (SG) and SG followed by film coating (SG-FC) using a fluid bed equipment, was investigated. In the 1st process, 3 types of fish oil used were based on the ratios of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (10/50, 33/22, and 18/12). Each type was emulsified with soluble soybean polysaccharide (SSPS) and maltodextrin to produce 25% oil powders. In the 2nd process, 15% film coating of hydroxypropyl betacyclodextrin (HPBCD) was applied to the granules from the 1st process. The powder stability against oxidation was examined by measurement of peroxide values (PV) and headspace propanal after storage at room temperature and at 3 to 4 degrees C for 6 wk. Uncoated powder containing the lowest concentration of PUFA (18/12) was found to be stable during storage at room temperature with maximum PV of 3.98 +/- 0.001 meq/kg oil. The PV increased sharply for uncoated powder with higher concentration of omega-3 (in 33/22 and 10/50 fish oils) after 3 wk storage. The PVs were in agreement with the concentration of propanal, and these 2 parameters remained constant for most of the uncoated powders stored at low temperature. Unexpectedly, the outcomes showed that the coated powders had lower stability than uncoated powders as indicated by higher initial PVs; more hydroperoxides were detected as well as increasing propanal concentration. The investigation suggests that the film-coating by HPBCD ineffectively protected fish oil as the coating process might have induced further oxidation; however, SG is a good method for producing fish oil powder and to protect it from oxidation because of the "onion skin" structure of granules produced in this process.

Sensory quality of functional beverages: bitterness perception and bitter masking of olive leaf extract fortified fruit smoothies.

Olive leaf extract (OLE) contains high amounts of oleuropein and hydroxytyrosol. The antioxidant capacity of these polyphenols makes OLE a promising ingredient for functional food. OLE causes very strong bitterness perception and can therefore only be formulated in low concentrations. In this research, bitter detection and recognition thresholds of OLE-fortified fruit smoothies were determined by a trained sensory panel (n = 11). Masking of the OLE's bitter taste was investigated with addition of sodium cyclamate, sodium chloride, and sucrose by means of a standardized ranking method and a scale test. Detection (5.78 mg/100 g) and recognition thresholds (8.05 mg/100 g) of OLE polyphenols confirmed the low formulation limits when bitterness was not masked by other substances. At higher polyphenol levels of 20 mg/100 g, sodium cyclamate and sucrose were able to reduce bitter taste perception by 39.9% and 24.9%, respectively, whereas sodium chloride could not effectively mask bitterness. Practical Application: Development of functional food poses new challenges for the food industry. A major problem in this field is the high bitterness of natural polyphenol-containing extracts with potential health benefits. This research was conducted to understand the sensory impact of olive leaf extract (OLE), a novel food ingredient with very bitter taste. In product development, the data of this research can be considered for formulation limits and the general sensory quality of OLE-fortified food and beverages.

Fish oil stabilisation by microencapsulation with modified cellulose.

Fish oil is the richest dietary source of long-chain omega-3 polyunsaturated fatty acids (PUFA). Stabilisation of omega-3 PUFA against oxidation is an important task in food processing. The ability of modified celluloses to act as microencapsulating agents for fish oil was investigated. Fish oil microcapsules were produced by spray-drying of homogenised emulsions containing modified celluloses and maltodextrin as coating materials. The quality of microcapsules was evaluated by scanning electron microscopy, determination of encapsulation efficiency, peroxide value during storage and solubility in water. Methylocellulose (MC) and hydroxypropyl methylocellulose (HPMC) showed good emulsifying properties. Homogenisation of emulsions resulted in creation of high amount of stable foam. More damage occurred in the powders coated with HPMC. The oil retention level was very high, 98.5% (i.e. up to 400.0 g/kg ready powder). Samples with fish oil content of approximately 500.0 g/kg exhibited more structural damage impairing the stabilisation effect. This study indicates that the use of modified cellulose, especially MC, as a coating material for the preparation of spray-dried fish oil microcapsules improves the stability and the concentration of fish oil in the powder.