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The influence of a food-grade long-chain polyphosphate mixture on the growth and survival of spoilage micro-organisms during storage in an experimental processed cheese spread formulation was evaluated. The emulsifying salt was added to the cheese blend at a concentration of 0.5% or 1.0%. A control product was also manufactured, which contained monophosphate instead of polyphosphate as emulsifying salt, with all other ingredients being identical to those in the experimental processed cheese spread. Half of the finished products were subjected to accelerated shelf-life testing at 37 °C for 10 days, whereas the other half of them was stored refrigerated at 4 °C for 120 days. Microbiological analyses (enumeration of viable cell counts, mesophilic sulphite-reducing clostridia, coliforms, yeasts and moulds) and sensory tests were performed at regular intervals. The results showed that polyphosphates had a beneficial effect on the shelf-life of the processed cheese spread tested in that they significantly reduced (P<0.05) the growth or survival rates of spoilage bacteria, especially of mesophilic sulphite-reducing clostridia. Polyphosphates also beneficially influenced the sensory, including textural properties of the experimental processed cheese spread. All the samples containing less than 1% polyphosphate showed signs of butyric blowing significantly earlier (P<0.05), during both accelerated shelf-life tests and regular refrigerated storage, than did the products fortified with 1% polyphosphate. In conclusion, the suitability of the long-chain polyphosphate formulation tested for shelf life extension of processed cheese spreads was demonstrated.

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The purpose of this research was to monitor the changes during storage in survival of bifidobacteria in a soft-frozen ice cream supplemented with a yeast cell wall-based product claimed to contribute to the functioning of the immune system. An ice cream mix was prepared and pasteurised. After overnight aging at 4 °C, it was inoculated with Bifidobacterium animalis subsp. lactis Bb-12. Two batches of the mix were supplemented with a commercial Saccharomyces cerevisiae cell wall product at 2.0% and 4.0% (w/w), whereas a third batch was left unsupplemented and served as control. The final mixes were frozen, and the three products were stored at –13 °C for 7 days. The ice creams contained viable bifidobacteria cells at levels exceeding 106 CFU g–1 throughout the storage throughout the storage period. Although the yeast supplement decreased the loss of viability of bifidobacteria during frozen storage of ice creams, it imparted a slightly bitter off-flavour to the samples and it also negatively influenced the original white colour of the product, thereby necessitating further work to develop flavoured varieties of the Saccharomyces cell wall-containing synbiotic ice cream.

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The importance of short food supply chains is increasing in the food sector, and direct selling is a promising alternative to commercial chains in dairy trade. Several channels and practices of direct raw milk sales exist in Hungary. Because short food supply chains in the Hungarian dairy sector have not yet been investigated in detail, we have little or no knowledge on the composition of directly sold raw milk. For this reason, a 9-month study was undertaken from June 2013 through February 2014, wherein directly sold raw bovine milk samples were tested for fat, protein, lactose, and solids-not-fat contents and for freezing point. A total of 21 direct sellers located in Budapest, Hungary were sampled twice a month. The results were compared to the official Hungarian raw milk quality data referring to the same period. The direct milk vendors involved in this study were found to sell raw milk with reduced levels of lactose and solids-not-fat and elevated freezing points, compared to the national raw milk data. The findings of this research underline the need for stricter regulations and control with respect to direct raw milk sales in the country.

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We are synthetized thermo- and pH-sensitive gels, which are then tested as skin extenders. Our aim is the development of copolymer and composite hydrogels that, when implanted under the human skin, swell osmotically and thereby induce skin growth. During the polimerization reaction we are produced copolymers with varyable composition, which are proceed from two acrylic compounds [N- isopropyl- acrylamide (NIPAAm), and acrylamide (AAm)]. The mechanical strength and the swelling stability of the gels are enhanced by the addition of fillers [Na- montmorillonite (Na- m.) and with alkyl- ammonium ion organophilized Na- montmorillonites [(C n - m.), n = 4, 12, 18]. With this method we are synthetized composite- hydrogels. The filler content of composites varies between 1 and 25 wt%. We observed that in the case of composites synthesized with the addition of fillers, relatively low filler contents (1–5 wt%) resulted in more extensive swelling and stronger gel structure. In the course of the experiments the monomer composition of the gels (0/100–100/0 mol% NIPAAm/AAm) and in the case of composites, the quality (montmorillonite and organophilized montmorillonite) and quantity (1–25 wt%) of fillers are varied. The extent of swelling and the viscoelastic properties can be manipulated through the ratios of these parameters. In the case of certain copolymer and composite gels, values of desorption enthalpy (ΔH m ) corresponding to the actual water contents were also determined by thermoanalytical measurements (DSC). Swelling values determined by gravimetry and enthalpies calculated from DSC measurements were found to be in good correlation. Evaluation and comparison of the rheological and DSC results also allowed conclusions to be drawn concerning the types of interaction operating among the three components of the system, i.e. the polymer skeleton, the filler and water molecules. We found that water molecules within the gel matrix are bound to the 3-D polymer lattice with bonds of different strengths and the strength of these interactions are dependent on both hydrophilicity and charge conditions. In the case of hydrophobic NIPAAm composites a more extensive swelling can be achieved by applying montmorillonite fillers with hydrophobized surfaces, whereas in the case of hydrophilic AAm-based composites the use of hydrophilic montmorillonite fillers ensure more extensive swelling.

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Thirty-three varieties of dairy products were analysed for fat and cholesterol contents, and a high correlation (r=0.983) was found between these two compositional attributes. Cholesterol concentration was independent of processing factors such as heat-treatment of the raw material, use of starter culture, type of the starter organisms employed and whipping or flavouring of the product. The non-fat varieties of fluid, fermented and dried milks showed significantly increased cholesterol-to-fat ratios compared to the other products tested because they contained considerable amounts of small fat globules and, therefore, had a large surface area with cholesterol bound to the fat globule membranes. The results of this study may be useful when establishing dietary guidelines for the general public according to health concerns, when formulating diets for population groups with special requirements or when assessing fat and cholesterol intakes in epidemiological studies aimed at investigating the relationship between diet and health.

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Acta Alimentaria
Authors:
L. Varga
,
R. Engel
,
K. Szabó
,
L. Abrankó
,
B. Gosztola
,
É. Zámboriné Németh
, and
S. Sárosi

Ground ivy (Glechoma hederacea L.) is one of the prosperous plants for the food-industry as natural antioxidant. This fact led us to examine the chemical diversity of six ground ivy populations situated in different natural habitats and to analyse the effect of the harvesting time. Total phenolic content, chlorogenic acid, and rutin content, as well as the antioxidant capacity showed significant differences due to the harvest time. The highest total phenol content (115 mg g–1 GAE) and the strongest antioxidant activity (53.3 mg g–1 AAE) were measured in the population originated from Budapest (GLE 6), harvested in July. The highest chlorogenic acid (357 mg/100 g) and rutin (950 mg/100 g) contents were detected in the July harvested samples from the Soroksár Botanical Garden population (GLE 1). According to our results, the collection time has significant effect on the total phenolic content – first of all on the chlorogenic acid and rutin accumulation levels of ground ivy, while the influence of the habitat seems to be less important.

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Acta Alimentaria
Authors:
M. Szalai
,
J. Szigeti
,
L. Farkas
,
L. Varga
,
A. Réti
, and
E. Zukál

The shelf-lives of major commercial cooked meat products (i.e., Bologna sausage, Italian-type cooked sausage, and cooked ham) packaged under vacuum or modified atmospheres were tested in this study. Samples were taken from commercial meat processing lines, sliced to 1.2 mm thickness and placed overlapped into polypropylene trays sealed with plastic films. The headspace of modified atmosphere packaged formulations consisted of 30% CO2 and 70% N2 or 60% CO2 and 40% N2. The samples thus produced were stored under refrigerated conditions. The values of microbiological, chemical, physical or sensory properties were plotted against storage time, and Gompertz curves were fitted to all time series that changed from an initial to a final value during any period of storage. The influence of headspace CO2 concentration on the properties of sliced cooked meat products varied considerably and, therefore, it was not possible to specify general rules. However, the presence of CO2 in the packaging atmosphere slowed down the rate of microbial growth, thereby delaying the spoilage of meat products. A CO2 level of 60% had beneficial effects on both the microbiological and sensory properties of sliced sausages and cooked ham. It was concluded that cooked meat products packaged under modified atmospheres had a shelf-life of 20 days.

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Acta Alimentaria
Authors:
A. Tonamo
,
I. Komlósi
,
L. Varga
,
M. Kačániová
, and
F. Peles

Abstract

The objective of this study was to use matrix-assisted laser desorption ionisation–time of flight mass spectrometry (MALDI-TOF MS) for the identification of ovine-associated staphylococci. Presumptive Staphylococcus isolates were recovered from ovine udder surface (US), individual raw milk, bulk tank milk, and cheese samples and were characterised by conventional phenotypic methods. A total of 69 bacterial isolates were further confirmed by MALDI-TOF MS. Forty-two (60.9%) of 69 isolates were successfully identified on genus and species level. Two thirds (n = 28) of the 42 identified isolates were shown to be Staphylococcus spp. These 28 staphylococcal isolates formed two clusters, one consisting of 22 Staphylococcus aureus strains and the other composed of 6 non-aureus staphylococci, including S. simulans (n = 3), S. auricularis, S. equorum, and S. haemolyticus. MALDI-TOF MS has proven to be a reliable tool for the identification of staphylococci from raw sheep's milk, especially bulk tank milk; however, currently it appears to be less useful for the identification of bacterial isolates originating from ovine US samples. This is the first study to evaluate the applicability of MALDI-TOF MS for identification of Staphylococcus spp. in ovine raw milk, cheese, and US samples in Hungary.

Open access
Acta Alimentaria
Authors:
J. Csapó
,
J. Schmidt
,
Zs. Csapó-Kiss
,
G. Holló
,
I. Holló
,
L. Wágner
,
É. Cenkvári
,
É. Varga-Visi
,
G. Pohn
, and
G. Andrássy-Baka

In the past years several methods have been developed for the determination of the proportion of the nitrogen-containing substances of microbial origin passed from the rumen into the abomasum or the small intestine. Recently, on examining the D-amino acid content of foodstuffs, particularly milk and milk products, it has been observed that, in addition to D-Ala, D- glutamic acid (D-Glu) and D-aspartic acid (D-Asp) can also be detected in similar quantities, primarily in products which have links with bacterial activity. This gave rise to the idea of examining the diaminopimelic acid (DAPA), D-Glu and D-Asp content of bacteria extracted from the rumen of cattle and that of chyme from the same cattle, in order to determine the type of relation existing among these three components, and to establish whether D-Asp and D-Glu can be used in the estimation of protein of bacterial origin. On determination of the DAPA, D-Asp and D-Glu content by means of amino acid analyser and high performance liquid chromatography of duodenal chyme from five growing bulls and of ruminal bacteria from the same bulls, the following values were established. For chyme (and, in brackets, for ruminal bacteria) r value calculated by means of linear regression was 0.78 (0.76) between DAPA and D-Asp, and 0.70 (0.81) between DAPA and D-Glu. The r values between the crude protein content of ruminal bacteria and the markers examined were found to be the following: DAPA, 0.74; D-Asp, 0.73; D- Glu, 0.61. In the model experiment performed for the re-obtaining of values for protein of bacterial origin the theoretical values were determined on the basis of D-Asp and D-Glu and values approximately 10% higher than the theoretical value on the basis of DAPA. It is therefore recommended that in addition to DAPA these other two amino acids be included among the bacterial protein markers.

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