C. Ruiz-Capillas

Correlation between biochemical and sensory quality indices in hake stored in ice

Whole gutted hake was stored for 25 days in ice. Changes in pH, trimethylamine nitrogen (TMA-N), total volatile basic nitrogen (TVB-N), and lipid deterioration [2-thiobarbituric acid (TBA) index] was studied, and correlated with sensory analysis (inspection and tasting). There was a very high correlation between TMA-N and TVB-N indices. TBA levels remained very low throughout the assay and were correlated with the results found in the tasting analysis, where the tasters did not detect any rancidity. However, the TBA results had a very low correlation with the inspection analysis and the TMA-N and TVB-N analyses. The pH, TMA-N and TVB-N indices had a very high correlation with the sensory analyses, which means these parameters are more suitable as indices for spoilage of hake.

Technological and sensory characteristics of reduced/low-fat, low-salt frankfurters as affected by the addition of konjac and seaweed

This paper reports the effect of an edible seaweed, Sea Spaghetti (Himanthalia elongata), on the physicochemical (emulsion stability, cooking loss, colour, texture, residual nitrite and microstructure) and sensory characteristics of reduced- and low-fat, low-salt (NaCl) frankfurters prepared with konjac gel as a fat substitute. The effects on emulsion stability of substituting konjac gel for pork backfat were conditioned by the proportion of the substitution. Incorporation of a combination of Sea Spaghetti/konjac gel (accompanied by reduction in salt) increased (P<0.05) cooking loss and reduced (P<0.05) emulsion stability in the gel/emulsion systems. Incorporation of Sea Spaghetti/konjac gel produced a decrease (P<0.05) of lightness (L*) and redness (a*) values and an increase (P<0.05) of yellowness (b*) as compared to the other samples. The effect of adding seaweed on the texture parameters of low-salt frankfurters varied depending on the proportion of konjac gel used in the formulation. Morphological differences in frankfurter microstructure were observed as fat content was reduced and konjac gel increased. Incorporation of a combination of Sea Spaghetti/konjac gel caused the formation of a more heterogeneous structure, in which the seaweed was integrated in the meat protein matrix.

Composition and antioxidant capacity of low-salt meat emulsion model systems containing edible seaweeds.

The study was designed to determine the influence of the addition of edible seaweeds, Sea Spaghetti (Himanthalia elongata), Wakame (Undaria pinnatifida), and Nori (Porphyra umbilicalis), on fatty acid composition, amino acid profile, protein score, mineral content and antioxidant capacity in low-salt meat emulsion model systems. The addition of seaweeds caused an increase (P<0.05) in n-3 polyunsaturated fatty acids (PUFA) and a decrease (P<0.05) in the n-6/n-3 PUFA ratio. The thrombogenic index significantly decreased (P<0.05) in Nori and Wakame meat samples. Meat systems made with added seaweeds had lower (P<0.05) sodium contents than control samples. In general, addition of seaweeds to products increased (P<0.05) the concentrations of K, Ca, Mg and Mn. The presence of Nori caused an increase (P<0.05) in levels of serine, glycine, alanine, valine, tyrosine, phenylalanine and arginine, whereas Wakame and Sea Spaghetti produced no significant changes in amino acid profiles in the model systems. The inclusion of Sea Spaghetti increased the sulphur amino acid score by 20%. The added seaweeds supplied the meat samples with soluble polyphenolic compounds, which increased the antioxidant capacity of the systems. The polyphenol supply and antioxidant increase were greatest (P<0.05) in the samples containing Sea Spaghetti.

Design and nutritional properties of potential functional frankfurters based on lipid formulation, added seaweed and low salt content.

The aim of this paper was to design and analyse the nutritional composition (fatty acid profile, cholesterol, mineral and amino acid content) of low-fat frankfurters enriched with n-3 polyunsaturated fatty acids (PUFA) (using algal oil to add 400mg of docosahexanoic acid - DHA/100g of product) as affected by the addition of seaweed (5.5% Himanthalia elongata) and the partial substitution (50%) of animal fat by olive oil (as a source of monounsaturated fatty acids - MUFA) or combinations of olive oil and seaweed. Reduction of NaCl level was also studied. The presence of algal oil produced frankfurters with high long-chain n-3 PUFA contents. The partial substitution of the pork fat by olive oil reduced (P<0.05) saturated fatty acids (SFA) and promoted (P<0.05) MUFA. A healthier lipid formulation (algal and olive oils and the reducing animal fat) produced a good balance of MUFA/SFA, PUFA/SFA and n-6/n-3 ratios. Although adding seaweed had little effect on the lipid and amino acid profiles of frankfurters, it does constitute a means to produce low-sodium products with important dietary fibre content, with better Na/K ratios and rich in Ca.

Effect of total replacement of pork backfat with walnut on the nutritional profile of frankfurters

The nutritional profile of a frankfurter with walnut (25%) (WF) was compared with that of low fat (6%) (LF) and normal fat (16%) (NF) sausages. LF frankfurters did not improve the fatty acid profile as compared with NF (p>0.05), or the indices of atherogenicity (IA) (0.50) or thrombogenicity (IT) (1.12), indicating that the reduction of animal fat produced no cardioprotective effect. However, frankfurter with walnut had a healthy polyunsaturated fatty acid profile, a lower ω-6/ω-3 ratio and lower IA (0.10) and IT (0.15). In addition, WF could be a good source of manganese, iron, copper, potassium and magnesium, supplying 39%, 35%, 34%, 16% and 15% of the respective daily recommended intakes, respectively. Also, there were significant amounts of other bioactive components such as α-,γ- and δ-tocopherol, total dietary fibre, polyphenols and tannins. The amino acid composition of WF indicated a healthier lysine/arginine ratio (0.83) than in LF (1.23) and NF (1.19).

Nutritional profile of restructured beef steak with added walnuts

Amino acid, fatty acid profile, cholesterol, vitamin E and mineral contents were assessed in restructured beef steak with 20% added walnut (20W). Compared with control restructured beef steak (0% added walnut), the product with added walnut presented a lower (P<0.05) lysine/arginine ratio, larger (P<0.05) quantities (mg/100 g product) of monounsaturated (MUFA) and n3 polyunsaturated (PUFA) fatty acids (mainly α-linolenic acid), a lower (P<0.05) n6/n3 PUFA ratio and a higher (P<0.05) polyunsaturated/saturated fatty acid ratio. The replacement of raw meat material by walnut reduced (P<0.05) the cholesterol content and increased (more than 400 times) the amount of γ-tocopherol. Iron, calcium, magnesium and manganese contents of 20W sample were greater (P<0.05) than in the control. Some changes induced by added walnut in the nutritional quality of the restructured product may present health benefits.

Low-fat frankfurters formulated with a healthier lipid combination as functional ingredient: microstructure, lipid oxidation, nitrite content, microbiological changes and biogenic amine formation.

Oil (healthier lipid combination of olive, linseed and fish oils)-in-water emulsions stabilized with different protein systems (prepared with sodium caseinate (SC), soy protein isolate (SPI), and microbial transglutaminase (MTG)) were used as pork backfat replacers in low-fat frankfurters. Microstructure, lipid oxidation, nitrite content, microbiological changes and biogenic amine formation of frankfurters were analyzed and found to be affected by the type of oil-in-water emulsion and by chilling storage (2° C, 41 days). Although the lipid oxidation levels attained were low, replacement of animal fat by healthier oil combinations in frankfurter formulation did promote a slight increase in lipid oxidation. Residual nitrite was affected (P < 0.05) by formulation and storage. Only 51-61% of the added nitrite was detectable in the product after processing and 17-46% at the end of storage. The microbial population was low in all formulations during chilling storage. Spermine was the most abundant amine (19-20 mg/kg), but similar in level to all samples.

Konjac gel as pork backfat replacer in dry fermented sausages: processing and quality characteristics.

The effect of replacing animal fat (0%, 50% and 80% of pork backfat) by an equal proportion of konjac gel, on processing and quality characteristics of reduced and low-fat dry fermented sausage was studied. Weight loss, pH, and water activity of the sausage were affected (P<0.05) by fat reduction and processing time. Low lipid oxidation levels were observed during processing time irrespective of the dry sausage formulation. The fat content for normal-fat (NF), reduced-fat (RF) and low-fat (LF) sausages was 29.96%, 19.69% and 13.79%, respectively. This means an energy reduction of about 14.8% for RF and 24.5% for LF. As the fat content decreases there is an increase (P<0.05) in hardness and chewiness and a decrease (P<0.05) in cohesiveness. No differences were appreciated (P>0.05) in the presence of microorganisms as a result of the reformulation. The sensory panel considered that NF and RF products had acceptable sensory characteristics.

Nutritional and antioxidant properties of different brown and red Spanish edible seaweeds.

This article reports a study of the nutritional composition, total dietary fiber (TDF), mineral contents, fatty acid and amino acid profiles, polyphenolic concentration and antioxidant activity of three Spanish seaweeds: two brown seaweeds (Himanthalia elongata and Undaria pinnatifida) and one red (Porphyra umbilicalis). TDF and ash were the most abundant components in the brown seaweeds, while TDF and protein were the main components in the red one. In all seaweeds, the lipid contents were very low but the polyunsaturated fatty acid contents were high. Although the red seaweed contained significantly (p < 0.05) more protein content than the brown ones, all three contained all the essential amino acids at levels comparable to FAO/WHO requirements. The brown seaweeds contained significantly more minerals than the red one; they are a rich source of K, Na, Ca and Mg and present a beneficial Na/K ratio. Himanthalia elongata displayed remarkably high polyphenolic content, endowing it with appreciable antioxidant activity. These seaweeds offer considerable potential as functional food ingredients due to components like dietary fiber, minerals and trace elements, protein and lipids, which produce many different kinds of biological activities, and also to their high antioxidant capacity.

Production of biogenic amines by lactic acid bacteria and enterobacteria isolated from fresh pork sausages packaged in different atmospheres and kept under refrigeration

The occurrence of in vitro amino acid activity in bacterial strains associated with fresh pork sausages packaged in different atmospheres and kept in refrigeration was studied. The presence of biogenic amines in decarboxylase broth was confirmed by ion-exchange chromatography and by the presence of the corresponding decarboxylase genes by PCR. From the 93 lactic acid bacteria and 100 enterobacteria strains analysed, the decarboxylase medium underestimates the number of biogenic amine-producer strains. 28% of the lactic acid bacteria produced tyramine and presented the tdc gene. All the tyramine-producer strains were molecularly identified as Carnobacterium divergens. Differences on the relative abundance of C. divergens were observed among the different packaging atmospheres assayed. After 28 days of storage, the presence of argon seems to inhibit C. divergens growth, while packing under vacuum seems to favour it. Among enterobacteria, putrescine was the amine more frequently produced (87%), followed by cadaverine (85%); agmatine and tyramine were only produced by 13 and 1%, respectively, of the strains analysed. Packing under vacuum or in an atmosphere containing nitrogen seems to inhibit the growth of enterobacteria which produce simultaneously putrescine, cadaverine, and agmatine. Contrarily, over-wrapping or packing in an atmosphere containing argon seems to favour the growth of agmatine producer-enterobacteria. The production of putrescine and cadaverine was associated with the presence of the corresponding amino acid decarboxylase genes. The biogenic amine-producer strains were included in a wide range of enterobacterial species, including Kluyvera intermedia, Enterobacter aerogenes, Yersinia kristensenii, Serratia grimesii, Serratia ficaria, Yersinia rodhei, Providencia vermicola and Obesumbacterium proteus.