Susana Fiszman

Effect of addition of gelatin on microstructure of acidic milk gels and yoghurt and on their rheological properties

Abstract A study was made of the effect of the addition of gelatin on the microstructure of acid-heat-induced milk gels (90°C, pH=5.3) and yoghurt with and without the addition of 5% of milk solids, and a comparison was made with the microstructure of acidic milk gelatin gels obtained without heating (pH=5.3). It was seen that in the acid-heat-induced gels and in yoghurt the gelatin interacted with the network of milk proteins as a connection between the clusters formed, whereas it was the gelatin alone that was the basis of the formation of the gel when the milk did not reach the casein coagulation point (pH=5.3, unheated). The results of firmness tests indicated that the addition of 1.5% of gelatin developed fairly firm, deformable systems in all the cases studied, with a definite break point and almost total absence of syneresis. Dynamic rheology showed that the yoghurts with added gelatin exhibited more solid-like behaviour than the ones prepared without it.

Recent developments in coating batters

Abstract Products that are battered, prefried and then frozen constitute an extensive sector in the ready-meals market. The attempt to reduce the quantity of oil absorbed by products of this kind has prompted much recent research on the formulation of batter mixes, but it has not been the only aim. This article discusses the key factors for development of such products and the application of new techniques to control these factors, the addition of new ingredients, the interrelationship of the functionalities that they deploy, and the application of new technologies for the preparation and cooking of battered foods. An innovative formulation patented by the authors (assignee Adin SA, Valencia, Spain) is also presented, together with the process for its application, which eliminates the industrial prefrying step in the manufacture of frozen, battered products.

Innovative method for preparing a frozen, battered food without a prefrying step

The fundamentals and detailed description of the key steps of an innovative process for industrial battered food production that eliminates the prefrying step are presented. The process is based on the incorporation of methylcellulose (MC) in the batter formula. Thanks to its thermal gelation ability, MC allows the development of an appropriate consistency when the coated food item is immersed in a hot water bath (T=70 to 80 °C). Subsequent application of a heat impact treatment sets the gel structure, thus suppressing the thermoreversibility of the process. Battered squid rings were prepared in accordance with this method at two MC concentrations (1.5 and 2%, based on the dry mix), and the pickup of the product, and the final texture, color, and fat and moisture contents of the final fried external crust were evaluated. The MC levels studied in the present work did not affect color, yield, or fat and moisture contents significantly. Textural measurements showed an increase in maximum peak force with MC concentration, although no significant differences were found in the slope values of the penetrometry curves. The overall results reflect the suitability of the process. Of note is the extraordinarily low oil content of this innovative battered food after frying.

Evaluation of yogurt and various beverages as carriers of lactic acid bacteria producing 2-branched (1,3)-β-d-glucan

Probiotic cultures are increasingly being incorporated into a wide variety of food products. Although lactobacilli and bifidobacteria are the most frequently used, other lactic acid bacteria (LAB) have been reported to be potential probiotics. Of these, the cider isolates Pediococccus parvulus (strains 2.6 and CUPV22) and Lactobacillus suebicus CUPV221 produce a 2-branched (1,3)-β-d-glucan exopolysaccharide that decreases serum cholesterol levels and affects the activation of human macrophages. For this reason, these 3 strains were incorporated into yogurt, orange juice, and 2 juice-milk beverages to evaluate the effect of the food matrix on the resistance of these strains to simulated gastrointestinal tract conditions. Our results showed that incorporation of the LAB did not significantly affect the physical and rheological properties of the food matrices tested. When incorporated in yogurt, LAB strains population decreased by 2 to 3 log orders of magnitude during the shelf life of the product (28 d). However, no significant decrease was observed in the juice and juice-milk beverages during the same storage period, except for Lb. suebicus, whose viability decreased by 3 log orders of magnitude. When strains were subjected to gastrointestinal tract conditions, a decrease in the survival was observed at the lower pH (1.8). However, incorporation of these LAB strains into orange juice increases their resistance to lower pH conditions, thus improving survival to gastrointestinal stress. Moreover, a protective effect was observed for P. parvulus CUPV22 and 2.6 to gastric stress in juice-milk beverages and to gastrointestinal stress in yogurt. Lactobacillus suebicus CUPV221 did not survive when incorporated into yogurt and juice-milk beverage.

Influence of nutritional knowledge on the use and interpretation of Spanish nutritional food labels.

UNLABELLED The present study analyzed the nutritional knowledge of Spanish consumers and its relationship with the correct use of food labels. Consumers were asked about their nutritional knowledge and some functional foods and about their understanding of food labeling and their use of it to select healthy food. A 2-part questionnaire was employed. The 1st part concerned their knowledge of nutritional facts, including their knowledge about macronutrients and perception of certain functional foods, while the 2nd part addressed some questions regarding food labels. The results revealed no statistically significant differences in nutritional knowledge by either age or gender, but a direct relationship with educational level. The association between nutritional knowledge and the perception and understanding of food labeling showed that the nutritional label rarely influenced the food purchases of the group with low nutritional knowledge, who considered that this information was too technical. More than half of the consumers did not consider the calorie or sugar content important for selecting food. In addition, the group with low nutritional knowledge stated that they never or rarely looked at the food labels to check whether it was low-fat food that they were buying. PRACTICAL APPLICATION Knowing the status of the consumers nutritional knowledge allows health campaigns to be designed; considering the influence of cultural factors and the perception of food labeling is very useful for promoting better nutritional information.

Rheological properties of batters for coating products: Effect of addition of corn flour and salt

The contributions made by corn flour (0, 3 and 6%) and salt (0 and 5.5%) to the rheological properties of a commercial batter mix were studied. The properties of the wheat flour that are the base of the mix were studied first, then the corn flour, salt and other ingredients were added step by step. All the samples showed a shear-thinning behaviour. An increase in the consistency index was obtained when corn flour was present, while the presence of salt produced a remarkable decrease. No differences in viscoelastic behaviour were found when corn flour up to 6% was added, and the behaviour had a clear elastic component. The addition of salt produced a more viscous behaviour. An increase in the gelatinisation temperature of batters was observed in the formulations with salt.

Mechanical properties of kappa carrageenan—locust bean gum mixed gels with added sucrose

Abstract The mechanical behaviour of kappa carrageenan(C)—locust bean gum (LBG) mixed gels with sucrose added was studied. The total hydrocolloid content (HC) varied between 0.5 and 1.0%, and sucrose content between 0 and 60%. Two series of gels were prepared: one with hydrocolloids in the ratio LBG/C = 1/1, and the other with C only. The maximum rupture force ( F max ), deformability modulus ( E ap ), and resistance to wire cut ( W ) and knife cut ( K ) were measured. While values for all parameters increased with the addition of sucrose in C gels, a sharp fall in the values of F max , W and K was registered in C-LBG mixed gels at 60% sucrose concentration, which might be attributed to competition for water between sucrose and gum molecules, probably leading to a glassy structure. Sensory non-oral evaluation of gel texture confirmed the instrumental results obtained. In 0.75% HC mixed gels the point of structural change was observed at a concentration of ~50% sucrose.

Active compounds and distinctive sensory features provided by American ginseng (Panax quinquefolius L.) extract in a new functional milk beverage

American ginseng (Panax quinquefolius L.) has recognized neurocognitive effects, and a ginsenoside-rich extract of the root of the plant has been shown to improve cognitive functions in young adults. This study aimed at assessing the chemical and sensory profiles of a UHT-treated, low-lactose functional milk containing American ginseng. Individual ginsenosides in the milk were analyzed by HPLC. Descriptive sensory analysis was performed by a trained panel to quantitatively document sensory changes resulting from the addition of ginseng and the UHT process on flavored and unflavored milks. Consumer acceptance of the product was also investigated. Total ginsenoside content in the UHT-treated milk enriched with the ginseng extract after UHT process treatment was 7.52 mg/100 g of milk, corresponding to a recovery of 67.6% compared with the content in the unprocessed extract. The intake of 150 to 300 mL of this ginseng-enriched milk provides the amount of total ginsenosides (11.5 to 23 mg) necessary to improve cognitive function after its consumption. Both the presence of ginsenosides and their thermal treatment affected some sensory properties of the milk, most notably an increase in bitterness and metallic taste, the appearance of a brownish color, and a decrease in milky flavor. Levels of brown color, bitterness, and metallic taste were highest in the industrially processed ginseng-enriched milk. The bitterness attributable to ginseng extract was reduced by addition of vanilla flavor and sucralose. A consumer exploratory study revealed that a niche of consumers exists who are willing to consume this type of product.

Thermal degradation of green asparagus texture

A cutting cell was developed to evaluate the texture of green asparagus by measuring its resistance to being cut with a wire. The cell was used in conjunction with a universal texturometer and improved on the single-point method of the Wilder fibrometer. Experimental conditions were determined for using the cell to measure the cutting resistance of asparagus subjected to different extents of heat treatment. Better discrimination between samples was obtained than with a Kramer cell. The fresh asparagus spears. were heated at temperatures between 70 and 100°C for different lengths of time and the kinetics of the degradation of texture was studied. A biphasic (two-component) behavior was observed with each component displaying first-order kinetics, The kinetic parameters calculated by measuring the texture with the wire cell (cutting at a position 5 em from the tip of the asparagus) were Eaa = 9.56 and Eab = 20.43 kcal/mol (activation energy for components A and B), and ka85 = 1.047 and kb85 = 0.057 min-1 (rate constants for A and B of asparagus heated at 85°C). When the texture was determined by measuring the shear force with a Kramer cell, the parameters estimated were Eaa = 23.41 and Eab = 18.32 kcal/mol, and ka85 = 0.25 and kb85 = 0.025 min-1 Both the wire cell cutting method and the Kramer shear-press method are suitable for evaluating the degree of thermal softening of green asparagus heated to temperatures between 70 and 100°C.

Influence of composition on the resistance to compression of kappa carrageenan-locust bean gum-guar gum mixed gels: relationship between instrumental and sensorial measurements

The resistance to compression of kappa carrageenan-locust bean gum and carrageenan-locust bean gum-guar gum gels was studied by instrumental tests and by non-oral sensory evaluation. The study was performed in two series of 15 samples of 0.5 and 0.75% total hydrocolloid concentration (HC), the proportion of gum varying from 0 to 70%. The effects of type of gum and gum proportion, and their interaction on the different measured compression parameters—maximum rupture force, deformability moduli at two deformation ranges (10–20 and 20–30%), deformation to rupture and energy—were significant. These effects were also significant on some non-oral sensory parameters (P ≤ 0.05). Good correlations (0.87 < r < 0.96) were found between three sensory parameters: firmness, deformation before rupture and resistance to rupture; and three instrumental parameters: deformability modulus, deformation and maximum rupture force respectively.