Food Science and Technology International current issue

Mechanical and Physical Properties of Soy Protein Films with pH-Modified Microstructures

Mauri, A.N., Anon, M.C. — 2008-07-02

Mechanical, physical, and barrier properties of films obtained from soy protein isolate solutions at different pH were studied and correlated with the structural properties and the microstructure of films. Films obtained at pH 2 and 11, which had denser microstructures and a higher amount of disulfide bonds, showed a higher tensile strength — of about 1.05 MPa — and a higher Young's modulus — of at least 0.15MPa — than the one at pH 8. However, films formed at alkaline pH (8 and 11) exhibited a higher deformation than films at pH 2 — by about 70%. The presence of at least a protein fraction in native state allowed macromolecules to unfold during the mechanical test, reaching greater deformation before breaking. Acidic films exhibited higher water vapor permeability — of about 7 x 10^-11 g/m s Pa — and water content — of about 1.5% — and a lower glass transition temperature — of at least 15 °C — than basic ones, due to their higher hydrophilic nature.

Changes in Fatty Acid Composition of two Muscles from Three Different Iberian x Duroc Genotypes After Refrigerated Storage

Ramirez, M.R., Cava, R. — 2008-07-02

The changes of the fatty acid (FA) profile of 2 muscles Longissimus dorsi and Biceps femoris from 3 Iberian x Duroc genotypes were studied: GEN1: Iberian x Duroc1, GEN2: Duroc1 x Iberian; GEN3: Duroc2 x Iberian. GEN1 and GEN2 are reciprocal crosses while the difference between GEN2 and GEN3 is the Duroc sire line. The genotype Duroc1 was selected for the production of dry-cured meat products while the genotype Duroc2 was selected for meat production. Longissimus dorsi and Biceps femoris BF from the reciprocal cross showed similar changes in FAs profile after refrigerated storage. However, the Duroc sire line affected the FA profiles of intramuscular fat (IMF) and lipid fractions since some differences were found between GEN2 and GEN3. Meat from GEN3 had the highest level of polyunsaturated fatty acids (PUFA) in IMF and lipid fractions as well as the lowest rate of plasmalogens in polar lipid fraction. After storage, meat from GEN3 showed an increase of long chain PUFA in free fatty acids fraction and the highest increase in the ratio DMA/FA [(dimethylacetals/FAs) x 100] after the refrigerated storage, which was indicative of a higher deterioration of this genotype. Therefore, the crossbreeding of Iberian pigs with Duroc selected genotypes (Duroc2) could affect the changes in the FAs profile of meat under refrigerated storage.

Potential of Conceptual Design Methodology for Food Process Innovation

Hadiyanto, H., van Straten, G., Boom, R., van Boxtel, A.J.B., Esveld, D.C. — 2008-07-02

The available time span for food product and process innovation is steadily decreasing, and to increase the efficacy of the development cycles, systematic design procedures can be used to develop new and to redesign existing processes. The Conceptual Process Design (CPD) methodologies used in chemical industry might also be applied in the food industry to rethink their systems and to break down the complexity of problems into several hierarchical levels. The Delft design matrix, a combination of the iterative design procedure, hierarchical decomposition and task driven methods, is a promising tool which can cover the different objectives and criteria of food design. This article analyzes the potential applicability of Delft Design Matrix as a CPD methodology for food process design and illustrates its functionality with the design of a bakery production system.

Note. Genetic Diversity of Food Isolates of Salmonella enterica serovar Typhimurium in India

Saroj, S.D., Shashidhar, R., Bandekar, J.R. — 2008-07-02

The study aimed to determine the genetic diversity of Salmonella enterica serovar Typhimurium isolates from sprouts and fish samples from India. Twenty-eight S. Typhimurium isolates were genotyped by pulsed-field gel electrophoresis and tested for antibiotic susceptibility, plasmid profile, and presence of virulence genes (invA and spvC). Three distinct XbaI-pulsed-field profiles (PFPs) were observed. Out of 22 isolates from sprouts, 20 showed PFP-A and remaining two showed PFP-B. All six fish isolates showed PFP-C. All the strains were sensitive to the examined antibiotics except two strains of PFP-A. Two different plasmid profiles P1 and P2 were observed. P2 was observed only in the antibiotic resistant strains. All strains were positive for the invA, whereas spvC was detected only in sprout isolates. There was no specific pattern in occurrence of the genotypes with respect to seasons. However, PFP-A was dominant and was isolated throughout the year. This is the first report to assess the genotypic diversity of S. Typhimurium obtained in foods from India. As S. Typhimurium is the predominant serotype in India, the data generated in this study would be useful in epidemiological studies during outbreaks of Salmonellosis in India.

Sensory Profile of Mandarin Chilled Juices and Consumers' Acceptability

Carbonell, L., Navarro, J.L., Izquierdo, L., Carbonell, I. — 2008-07-02

Chilled mandarin juices from four different commercial brands, two mandarin juices prepared in our pilot plant and two commercial orange juices included for comparative purposes were scored for acceptability by 100 consumers in a unique evaluation session. Independently, a descriptive profile of the same samples was performed by 10 trained assessors, who quantified 29 sensory attributes. Most consumers preferred mandarin juices although a small group (about 10%) found orange juices more acceptable. No differences in acceptability were observed between samples from diluted concentrates and from direct juice, either mandarin or orange. Among sensory attributes, maximum differences between samples were found for color, pulp (aspect and texture), mandarin odor, mandarin taste, bitterness and persistent taste.

The Effect of Washing, Microbial Transglutaminase, Salts and Starch Addition on the Functional Properties of Sardine (Sardina Pilchardus) Kamaboko Gels

Karayannakidis, P.D., Zotos, A., Petridis, D., Taylor, K.D.A. — 2008-07-02

The functional properties of kamaboko gels, produced from sardine surimi (SS), were evaluated based on three factors: (a) washing conditions, (b) absence or presence of microbial transglutaminase (MTGase), and (c) addition of CaCl₂, MgCl₂, and NH₄Cl. Fish gels prepared from sardine mince washed at pH 5.5 showed the highest L* values and whiteness index (WI). A similar trend was also observed for firmness. Addition of MTGase had a beneficial effect on the L* values and WI as well as on firmness and cohesiveness of kamaboko gels (p<0.05). Fish gels containing CaCl₂ or MgCl₂ were lighter and firmer compared to those containing NH₄Cl (p<0.05). Three transitions, using a differential scanning calorimeter (DSC), were observed during heating of surimi containing 50g/kg of unmodified wheat starch (UWS), occurring at 45.2 °C, 63.3 °C, and 71.4 °C and were substantially the same when UWS was added at higher concentrations (p≥0.05). The thermal gelation of SS, studied with Dynamic Mechanical Analysis (DMA), occurred at three or four distinct stages named: gel softening, low temperature gelation, gel resolution, and high temperature gelation. The cooling process was found to be crucial in surimi gelation since it strongly contributed in the development of gel rigidity.

Enhancement of Modified Atmosphere Packaged Farmed Atlantic Halibut (Hippoglossus Hippoglossus) Fillet Quality by Soluble Gas Stabilization

Rotabakk, B.T., Birkeland, S., Lekang, O.I., Sivertsvik, M. — 2008-07-02

The suitability of soluble gas stabilization (SGS) to dissolve CO₂ into Atlantic halibut (Hippoglossus hippoglossus) fillets prior to modified atmosphere packaging (MAP) were investigated. Two levels of CO₂ partial pressures (200 and 400 kPa) and two levels of time (1 and 2h) with SGS treatment was used in a factorial design, and compared to conventional MAP. Headspace gas volume (mL), headspace gas composition (%), drip loss (%), pH, microbiological characteristics, off-odor and color were assessed on the packaged fillets. Increased partial pressure and increased SGS treatment time before MAP significantly ( p<0.001) increased the CO₂ content in the packaged fillets and counteracted package collapse. No interaction between the time and partial pressure was found. SGS treatment significantly (p = 0.038) reduced aerobic plate count (APC) and psychrotrophic count (PC). APC and PC increased significantly the tree first sampling days during storage (7, 15, and 21) and stabilized from day 21 to day 28. H₂S producing bacteria and Brochothrix thermosphacta was not affected by the SGS treatment. H₂S producing bacteria decreased significantly from day 7 to day 15. SGS treatment decreased the drip loss significantly (p = 0.006). Color and pH were not affected by the SGS treatment. No difference in the off odor was found between the treatments. Based on off odor analysis, the shelf life of the halibut fillet in this trial exceeded 28 days.

Organic Acids and Soluble Sugars in Edible and Nonedible Parts of Damson Plum (Prunus domestica L. subsp. insititia cv. Syriaca) Fruits During Development and Ripening

Garcia-Marino, N., de la Torre, F., Matilla, A.J. — 2008-07-02

The contribution of the seed and pericarp to the content of malic, quinic, citric and fumaric acids, and sucrose, fructose and glucose was determined during development and ripening of damson plum fruits. In whole fruit, (i) malic and quinic acids were the principal organic acids (OA) and their levels varied significantly, the highest being found at the beginning of the late-green stage; and (ii) the content of citric and fumaric acids was scarce but fluctuated remarkably towards development and ripening. In the seed, the levels of malic, quinic and fumaric acid were lower in ripening than at the beginning of maturation, and a notable synthesis of citric was found from the middle of maturation onwards. In mesocarp, however, malic, quinic, and citric acids peaked in the middle of maturation, whereas fumaric acid notably increased towards ripening. In epicarp, the maximum for the quinic and malic was found at the beginning of ripening and maturation, respectively. In the seed, all soluble sugars (SS) studied peaked at the middle of maturation, and while fructose and glucose (the most abundant SS) tended to be stored during ripening, sucrose (the most abundant in the edible part of fruit) decreased. All the SS studied tend to increase in mesocarp and epicarp throughout maturation and ripening.