Near infrared sensors for the precise characterization of salt content in canned tuna fish.

Non-invasive technologies could help to guarantee quality standards of canned tuna fish. The aim of this study was to investigate the ability of bench-top (FT-NIR) and low-cost (LC-NIR) near infrared spectrometers to determine salt content and texture in canned tuna. Salt content distribution was also investigated using hyperspectral imaging (HSI) and computed tomography. Spectra were acquired on canned tuna and reference analysis performed. Partial least squares regression and discriminant analysis were used to develop salt content predictive and texture classification models. Salt content predictive errors were 0.10%, 0.22% and 0.22% for FT-NIR, LC-NIR and HSI, respectively. Salt content was not always homogeneously distributed in the can which was attributed to the salt content differences between internal and external parts of the tuna fish. Low-cost sensors could be a suitable solution to standardise the production and enable precise nutritional labelling, but more sophisticated algorithms are needed to identify textural defects.

Influence of surfactants and proteins on the properties of wet edible calcium alginate meat coatings.

Calcium alginate structures are of interest as replacers for natural casings due to their high availability, biodegradability and low price. The aim of this paper is to study the effect of oil, surfactants and proteins (pea and collagen) on the water transfer, mechanical and microstructural properties of the wet calcium alginate films. The addition of oil and surfactants tended to reduce the water permeance and the weight loss rate, reaching values between those shown by natural and collagen artificial casings. The addition of proteins did not improve the adherence of the films and it decreased the maximum force of the film at puncture test, which was even lower with the presence of the surfactant E475. The TEM micrographs showed that the differences in mechanical properties are mainly related to the differences in the compaction of the microstructure. Wet alginate films with E475 are envisaged as a substitute of natural and collagen artificial casings in the stuffed meat products industry.

The effect of thermal processing condition on the physicochemical and sensory characteristics of fermented sausages dried by Quick-Dry-Slice process®.

The effect of different thermal processing conditions just after fermentation on physicochemical parameters and sensory attributes of salami and chorizo slices dried by Quick-Dry-Slice process®, was evaluated. Meat and common additives were mixed, stuffed and fermented. Previous to drying the sausages were subjected to thermal treatment at 53 °C at different exposure times (0, 50, 65, 80, 95 and 110 min). Finally, the sausages were sliced and dried using QDS process®. Color, instrumental texture and sensory analysis were performed. Lightness (L*) after fermentation increased with thermal processing in both products while redness (a*) and yellowness (b*) decreased only in salami. Thermal treatment after fermentation increased the initial force (F0). Cooked appearance, cooked fat odor, cooked flavor and stringiness increased when the thermal processing time was increased. Thermal processing of salami and chorizo at 53 °C for 50 min and drying up to 30% of weight loss resulted in a similar product to that obtained without thermal processing.

Technologies to shorten the drying period of dry-cured meat products.

Dry-cured meat products are well-known for their unique sensory characteristics. However, the traditional process is very time consuming. The process can be shortened especially by accelerating the drying period, which is the most time consuming. This paper deals with some technological, safety and sensorial aspects for producing fermented sausages and dry-cured hams when the process time is shortened. Different techniques, such as temperature increase and thickness reduction, and the effects of some ingredients and additives are discussed. A Quick-Dry-Slice process based on a continuous system that combines both convective and vacuum drying could accelerate the drying of slices after the desired pH is reached in fermented sausages. There are safety concerns when processes are shortened, but possible additional hurdles, such as the introduction of bacteriocin-producing starter cultures and high-pressure treatments at the end of the process, could reduce them. Methods to speed up the development of typical colour, texture and flavour and their limitations are also discussed.

Sorption isotherms of salted minced pork and of lean surface of dry-cured hams at the end of the resting period using KCl as substitute for NaCl.

The effect of KCl on sorption isotherms was determined on salted minced meat (with 0%, 30% and 100% molar substitution of NaCl by KCl) at 5°C and 25°C and meat from a 3mm thick slice from the surface of dry-cured hams (with 0% and 35% molar substitution of NaCl by KCl) held at 70-75%, 75-80% and 80-85% air relative humidity during the resting period. The sorption isotherms were determined gravimetrically by exposing the meat samples to several atmospheres of known relative humidity controlled by different saturated salts according to the COST90 method. The sorption equipment consisted of a chamber containing 11 containers, covering the water activity (a(w)) range from 0.112 to 0.946 at 25°C. The hermetically closed sorption containers filled with KCl and minced meat samples were irradiated at 3kGrey (gamma irradiation (60)Co). The water content at equilibrium was higher in minced meat with NaCl than in minced meat with KCl (100% molar substitution of NaCl by KCl) at 5°C within the range of 0.4313 and 0.7565 a(w). However, when substitution was 30% in minced meat and 35% in hams the isotherms were similar to isotherm without substitution.

Moisture diffusivity in the lean tissue of dry-cured ham at different process times.

The aim of this study was to determine the effective moisture diffusivity coefficient (D(e)) during dry-cured ham processing in two muscles, an internal one (Biceps femoris, BF) and an external one (Semimembranosus, SM), at different temperatures. Two adjacent samples, which included both SM and BF muscles, were selected after salting (PS), after resting (PR), after 4 months of drying (D1) and at the end of the process (D2). One was used to determine the initial profiles of moisture and NaCl/moisture and the other to determine D(e) at different temperatures (1 and 5°C in PS; 5 and 12°C in PR; 12, 19 and 26°C in D1; 19 and 33°C in D2). D(e) was higher in the muscle with the higher moisture content (BF) except in PS and PR, where a gradient of NaCl/moisture ratio was observed in SM muscle. There was a positive effect of temperature on D(e), but it decreased during processing of the dry-cured ham. A simple diffusive model, with a unique and constant moisture diffusivity coefficient or with a coefficient depending only on temperature, does not explain the whole drying process correctly. The effects of moisture content and the gradient of NaCl/moisture ratio on D(e) have to be considered.

NaCl content and temperature effects on moisture diffusivity in the Gluteus medius muscle of pork ham.

Dry-cured meat products are salted with different amounts of NaCl and then dried under different conditions (temperature and relative humidity) in order to stabilize the product. The effective moisture diffusivity values (D(e)) in Gluteus medius muscles, unsalted or soaked in different salting solutions (0.02, 0.05 and 0.08 kg NaCl/kg H(2)O), and dried at different temperatures (5, 13, 19 and 26 °C) and 80% of air relative humidity were determined. Water diffusion was only allowed parallel to meat fibre direction. The D(e) values were determined by applying Fick's second law. As temperature increased or NaCl content decreased, the D(e) increased. At low temperatures, the D(e) was less dependent on NaCl content than at higher ones. The energy of activation, obtained from the Arrhenius equation, is lower for unsalted compared with salted samples. Therefore, the effective moisture diffusivity of salted meat products is more sensitive to temperature variations than that of unsalted meat.

Effect of the relative humidity of drying air during the resting period on the composition and appearance of dry-cured ham surface.

This study evaluates the effect of three different relative humidities (RH) during the resting period on the composition of the external part of Semimembranosus muscle (2 mm thick) and the appearance of the surface of the dry-cured ham after resting and ageing. Forty-eight hams stored after salting for 40 days at 4±1 °C and three different RH (52±3, 78±3 and 85±3%) were studied. Half of the hams in each treatment were sampled after the resting period and the rest were aged for 8 additional months at the same temperature and RH. Storage of hams at 52% RH during resting produced a white appearance in some parts of the rind and increased the surface covered with oil drip. Hams stored at 78% showed a similar composition to those stored at 52%, except for the higher moisture content and lower Na/moisture ratio at the end of the resting period, and potassium content (on dry matter, dm) at the end of the process. At the end of resting no white rind was observed, and at the end of the process the surface covered with oil drip was slightly lower than at 52%. Storage of hams at 85% RH increased the surface pH, Na2HPO4.12H2O crystallisation, Mg (dm), Mg/moisture, K (dm) and NPN/NT at the end of the resting period, and increased the pH and Mg (dm), Mg/moisture, Na/moisture, K/moisture, the ash (dm) and ash/moisture contents and decreased the a(w) and the surface covered with oil drip at the end of the process.

Meat pH and meat fibre direction effects on moisture diffusivity in salted ham muscles dried at 5 °C.

The effects of meat pH and meat fibre direction on the effective moisture diffusivity coefficient (D(e)) in salted ham muscles dried at 5 °C and 80% of air relative humidity were studied. Parallelepipedic meat samples from different muscles in the ham (Gluteus medius, Semimembranosus and Biceps femoris) were salted (0.08 kg NaCl/kg d.m.) and drying was only allowed through two faces of the sample by covering the other faces with PVC film. D(e) values were determined by Fick's 2nd law. D(e) parallel to the meat fibre direction in samples of Gluteus medius muscles was not affected by pH in the range 5.3-6.7. No significative differences in D(e) between the three muscles were detected (D(e) values ranged from 2.03×10(-11) to 2.55×10(-11) m(2)/s). D(e) perpendicular to meat fibre direction was 31% lower than D(e) parallel. The fibre direction effect was independent of the muscle.

The effect of sodium chloride content and temperature on pork meat isotherms.

The knowledge of sorption isotherms is essential for understanding the drying process. Throughout the dry cured meat process, changes occur in the NaCl content and temperature on the surface of meat products. The aim of this study was to obtain the desorption isotherms from raw and salted meat at different air temperatures and NaCl content. The desorption characteristics were studied in the relative humidity range of 11.2 to 94.5 % at storage temperatures of 5, 13 and 26°C and at 0, 8, 20 and 30% (dm) of added salt (NaCl). The salted meat samples isotherms at 26°C shows a breaking point between water activities (a(w)) of 0.70 and 0.75. At a(w) lower than 0.70, NaCl content and temperature have only a slight effect on water content equilibrium. At a(w) above 0.75, water content equilibrium increased with the increase in NaCl content and the decrease in temperature. A significant NaCl*Temp interaction was detected at a(W) 0.903 and 0.946.