Benno Kunz

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.

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.

Use of Pervaporation‐Bioreactor Hybrid Processes in Biotechnology

Pervaporation is a membrane separation process with considerable innovative possibilities in the area of biotechnology. Above all, the combination of bioreactor and pervaporation has potential in the longer term as an alternative to conventional batch processes. This article considers the state of the art pervaporation-bioreactor hybrid processes. The possible applications of such hybrid processes are discussed and compared with conventional processes. It becomes apparent that the use of pervaporation-bioreactor hybrid processes can avoid product inhibition and greatly enhance the productivity of biotechnological processes.

Mycelial Deformations of Cladosporium herbarum due to the Application of Eugenol or Carvacrol

ABSTRACT Varying concentrations of eugenol and carvacrol were added to cultures of Cladosporium herbarum to determine their effect on the growth and cell morphology of this common food spoiling mold. Microscopically, significant morphological deformations of the hyphae in relation to their age could be observed. These phenomena were accompanied by macroscopic changes of the colonies in combination with substantial growth inhibitions. Carvacrol possessed a higher antifungal activity than eugenol.

Rejection of acetic acid and its improvement by combination with organic acids in dilute solutions using reverse osmosis

Detailed knowledge of the reciprocal interactions of different solute components in RO, their permeation capacity and their influence on the level of rejection is scarce. In order to examine whether and to what extent the rejection of a target substance is influenced by the addition of other substances during RO, the alteration of permeability of acetic acid through a polyamide membrane was investigated. Therefore, acetic acid was combined with 26 further acids.

The influence of intermolecular interactions on the selectivity of several organic acids in aqueous multicomponent systems during reverse osmosis

Abstract This work investigates the extent to which the rejection of a target substance is influenced by the addition of other substances. The alteration effects on the permeation of acetic acid through a aromatic polyamide membrane when combined with one of 27 further organic acids was studied. The operating conditions were kept constant during all investigations. It was found that the retention of a target substance was dependant on the other compounds in particular aromatics and short-chained monocarboxylic and dicarboxylic acids. Acids which significant influenced acetic acid retention were additionally combined with other target substances, formic and propionic acid. The results showed that, in general, it is only possible to increase the direction of the target substances rejection, a higher rejection can only be increased, a lower rejection can only be decreased. These results were used to create and investigate quaternary solutions which showed that, in principle, it is possible to intensify the increasing effect of retention. Using the experiment data it should be possible to determine the separation capacity by concentration complex mixtures through reverse osmosis (RO).

Use of spice mixtures for the stabilisation of fresh portioned pork

Abstract During storage, fresh portioned meat is prone to microbial decay accompanied by smell and colour deterioration. As spices possess anti-microbial activity, they might be used for prolonging the shelf-life of meat. The present communication reports first results concerning this topic. Five spice mixtures adapted to the European taste were studied with respect to their stabilising effect on colour and smell of fresh portioned pork. Two of these spice mixtures were especially active. These mixtures diminished the bacterial count of pork and inhibited the growth of various meat-spoiling microorganisms in a model medium.

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 OLEs 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.

Contamination of different muesli components by fungi

16 different muesli components were studied for mould contamination and their qualitative mycobiota on three media. High counts of moulds were found in hazelnuts, cashew kernels, sunflower seeds, cornflakes, peanuts and almonds. Linseeds, raisins and different kinds of grain products showed lower contamination. The fungal flora consisted of 60 different species belonging to 21 genera. Penicillium (19 species), Aspergillus (11 species) and Eurotium (4 species), together with the Mucoraceae, predominated.

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.