IMPACT OF INGREDIENTS AND PROCESSING TECHNOLOGIES ON STRUCTURAL AND NUTRITIONAL PROPERTIES OF REDUCED-FAT FOODS

In the last decades, the demand for nutritionally-improved food has raised, drawing the attention of researchers on new solutions for product development. The design of foods able to satisfy specific sensory and nutritional functionalities requires a better understanding of the relationships between the composition of food materials, the effects of processing on their quality characteristics and structure, and their behavior during digestion. This PhD thesis aimed at evaluating how ingredients and technology affect structural properties of different reduced-fat matrices. Biscuits and whipping cream were used as case studies with different specific aims concerning the effects of ingredients and/or production technology. In particular, resistant starch, raw and extruded bean flour were evaluated as structuring ingredients in reduced fat biscuits, in combination with polydextrose or double emulsion as fat replacers. The effect on structural, nutritional and sensory properties of final biscuits were investigated. For whipping cream, gelatin addition and homogenization condition effects on structure and stability were evaluated, both immediately after production and after three weeks of storage. Design of Experiments techniques coupled with Response Surface Methodology were used for the multivariate investigation of both formulation and processing effect. Results from the biscuit case study demonstrated that combination of polydextrose and resistant starch allowed to obtain a reduced-fat biscuit (- 44 % fat) with structural characteristics similar to those of a standard full-fat biscuit prepared with shortening or butter. The use of extruded bean flour allowed to obtain biscuits nearly comparable to a traditional reduced-fat product, but with improved nutritional profile. The presented data suggest a hypoglycaemic potential of bean-enriched biscuits, to be confirmed by a dedicated in vivo study. Desirable nutritional value of bean powders, including high protein content and slow starch digestibility, may be successfully exploited in biscuits. On the other hand, the study of double emulsions by D-optimal design allowed to improve the knowledge about the effect of internal water gelling and the proportion of water and oil in the emulsion on yield, rheological behaviour and stability. However, the use of double emulsion in reduced-fat biscuits requires further investigations, in order to understand how to improve emulsion structuring and its effect on dough properties. Results from the whipping cream case-study demonstrated that the combination of gelatin addition and high homogenization pressure may be successfully exploited for the development of reduced-fat whipping cream (25 g/100g fat), with good quality characteristics and stability. D-optimal design and Response Surface Methodology resulted to be effective tools for the study of cream processing at a pilot level, allowing the collection of high quality information on the effect of the studied factors and their interactions, with a limited experimental effort. In particular, gelatin addition at a concentration of 0.25 g/100g, in combination with k-carrageenan, increased initial consistency of cream samples, leading to final overrun values even improved with respect to those obtained for commercial samples, without affecting texture properties and stability. Depending on gelatin concentration, homogenization pressure revealed a great potential to modulate whipping properties. The multidisciplinary approach adopted, comprehensive of all the functionality aspects related to a food product, may represent a starting point for the design of foods with targeted quality features and behavior during consumption. In such a complex investigation field, Experimental Design techniques coupled with multivariate analyses of the experimental data have confirmed to be effective tools for the characterization and optimization of both food formulation and processing. The developed mathematical models can be applied for reverse engineering and quality-by-design approaches, thus benefit both researchers and companies

Honey, trehalose and erythritol as sucrose-alternative sweeteners for artisanal ice cream. A pilot study

The use of sucrose-alternative sweeteners in ice cream production could satisfy requirements of modern consumers focused on natural and nutritionally balanced foods. The aim of this work was to fill the gap in basic knowledge about the effects of honey, trehalose, and erythritol on the properties of artisanal ice cream. A milk-based sucrose-sweetened ice cream was produced as reference sample (REF), using then the alternative sweeteners to partially (50%) or totally (100%) substitute sucrose. With respect to REF, honey-containing ice cream mix revealed a significantly lower value of soluble solids (30.4 \ub0Bx vs. 34.5 \ub0Bx) and apparent viscosity (36.5 mPa s vs. 47.6 mPa s) and a significantly higher extrusion time (8.18 min vs. 7.04 min). The total substitution of sucrose with trehalose and erythritol led to a melting rate (2.07 and 1.56 g/min, respectively) significantly lower than REF (2.75 g/min), a very high firmness (508 and 725 N vs. 4 N), and a higher extrusion temperature ( -7.1 and -5.3 \ub0C vs. -9.3 \ub0C). The results of this study represent a guideline for the successfully utilization of honey, trehalose, and erythritol in peculiar ice cream formulations (e.g. non-sweet or low-calorie products)

Sunflower oil organogels and natural sucrose alternatives: new ingredients for healthier artisanal ice creams

Food technologists are continuously looking for healthier ingredients with positive physiological effects in order to reformulate products traditionally rich in saturated fat and sugar. As regards ice creams, milk cream substitution with vegetable oils can reduce the intake of saturated fatty acids, which have been associated with higher levels of blood cholesterol and higher risks for coronary heart disease. As for sugar, erythritol and stevia have recently gained attention as natural sucrose alternatives, due to their zero calorie and glycaemic index. Thus, the aim of this work was to study the use of sunflower oil organogels (OG), stevia and erythritol as new ingredients for the development of healthier artisanal ice creams, able to satisfy dietary restrictions while maintaining good quality traits. In a first set of trials, ice creams containing 4 and 8% OG structured with 12% phytosterols were compared to traditional formulations made with 4 and 8% milk cream. Then, a second set of trials implied the preparation of an ice cream containing 4% OG, sweetened with 2.26% erythritol and 0.02% stevia instead of sucrose. All samples were produced in duplicate using a plant for artisanal ice cream. Milk cream substitution with OG gave good results, especially in terms of overrun and melting resistance. The combination of OG with erythritol and stevia allowed the production of an ice cream with physico-chemical features totally comparable to the traditional formulation, except for a higher instrumental firmness. In summary, the work demonstrated that OG, erythritol and stevia can be successfully exploited in the formulation of a low-calorie ice cream, enriched with high levels of polyunsaturated fatty acids and natural antioxidants

Optimization of a low fat and high resistant starch biscuit formulation

The detrimental effects of food over-consumption are raising a growing concern worldwide, implying high sanitary and social costs. Dietary-correlated diseases are considered among the leading risk factors of mortality. In this context, the production of foods able to satisfy dietary restrictions while maintaining acceptable structural and sensory characteristics is still a great challenge for industries. In particular, the relationships amongst food processing, texture and nutritional characteristics are seldom considered. This work represents the first phase of a wider project aiming to investigate how different production technologies can be used in order to obtain low fat (LF) and low glycaemic index (LGI) biscuits with quality features comparable to those of the traditional counterparts and a better nutritional functionality. In particular, a Central Composite Design of Experiment (CCD) has been developed in order to optimize the LF-LGI biscuit formulation. The reduction (0-50%) of vegetable shortening and the substitution rate (0-80%) of wheat flour with a high amylose maize starch (source of resistant starch) have been considered as CCD factors. Thus, a total of 13 production trials have been planned, including four replicates of the central point. Rheological properties and density of the biscuit doughs were analysed. Biscuits were characterized in terms of proximate composition, resistant starch content, geometrical features, colour, milk absorption, and texture (by means of a three-point bending test). Response surface methodology and desirability function will be applied to the analytical data, in order to study the main effects and their interaction and to optimize the biscuit formulation. Results of this part of the wider project will increase the knowledge about the effects of fat reduction and resistant starch addition on biscuit quality characteristics. They will represent a reliable starting point for the subsequent study of the impact of production technology on structure and nutritional features of the product

Impact of production technologies on structural and nutritional properties of low fat foods

The present project aims at investigating how different production technologies can be used to obtain low fat (LF) products (i.e., biscuits and mousses) with improved nutritional functionality and quality features comparable to those of the traditional counterparts. In particular, extrusion-cooking and depositing technologies will be compared for LF biscuits production, while high-pressure homogenization and blending will be compared for the pre-mix preparation of LF mousses. The importance of understanding interlinks between production technology, nutritional properties and sensory quality lies in the possibility to develop new approaches in process/product optimization and a broader variety of healthier products of high quality

Organogels as novel ingredients for low saturated fat ice creams

The aim of this work was to evaluate the use of sunflower oil organogels made with phytosterols and \u3b3-oryzanol as milk cream substitutes in artisanal ice creams. Fat amount (4 and 8 g/100 g) and type (milk cream, sunflower oil, and organogels containing two levels of gelators) were considered as factors. The higher fat amount significantly decreased density (1.08\ub10.01 g/mL vs 1.10\ub10.01 g/mL) and soluble solid content (27.2\ub10.3 \ub0Bx vs 30.1\ub10.3 \ub0Bx) of mixes, as well as ice cream overrun (31.1\ub10.6% vs 37.3\ub10.6%) and melting rate (2.5\ub10.1 g/min vs 2.9\ub10.1 g/min). The use of organogels with the highest gelator concentration yielded ice creams with quality characteristics comparable to those of the samples containing milk cream, and even better overrun (42.4\ub10.8% vs 37.1\ub10.8%) and melting starting time (20\ub11 min vs 16\ub11 min). Thus, the application of organogels in artisanal ice creams is a successful approach in order to obtain \u201clow saturated fat\u201d products (saturated fat < 0.9 g/100 g) \u201cwith added plant sterols and stanols\u201d intended for people who want to lower their blood cholesterol level

Whey Protein Concentrate and Egg White Powder as Structuring Agents of Double Emulsions for Food Applications

This work aims at studying the effects of whey protein concentrate (WP) and egg white powder (EW) as structuring agents in double emulsions (W1/O/W2). A D-optimal design was developed considering the following factors: type (WP, EW) and concentration (0, 5, 10&nbsp;g/100&nbsp;mL) of protein used to gel the inner water phase (W1), W1 volume percentage (20%, 30%, and 40%) in primary emulsion (W1/O), and W1/O volume percentage (40, 50, 60%) in W1/O/W2. The 21 samples were investigated by FT-IR spectroscopy, which revealed different protein conformations depending on W1 and W1/O fractions, and a better interaction with oil of WP rather than EW. Highly significant (p &lt; 0.001) multivariate models were computed for yield, rheological properties, and creaming stability of W1/O/W2, being W1 and W1/O the most influent factors. Protein type significantly affected W1/O/W2 rheology, revealing a better structuring ability of EW with respect to WP, resulting in higher apparent viscosity and consistency coefficient values. A W1/O/W2 optimized for maximum values of apparent viscosity, yield, and creaming stability was developed, composed of 10&nbsp;g/100&nbsp;mL EW in W1, 29% W1, and 60% W1/O, with an oil content of 42.6&nbsp;mL/100&nbsp;mL. The optimized emulsion gave results in good agreement with the predicted values, thus confirming the validity of the developed multivariate models for the design of double emulsions with desired features

Egg white powder as gelling and stabilising agent for double emulsions

Water-in-oil-in-water double emulsions (W1/O/W2) consist of small droplets of an inner water phase (W1) entrapped in oil droplets (O) that are, in their turn, dispersed in another aqueous phase (W2). They have the typical structure of oil-in-water (O/W) emulsions but with a reduced fat content, thus resulting interesting for the development of reduced-fat foods. The main issue connected to real applications is the ability to mimic fat behaviour while showing a prolonged stability during storage. Gelling of the internal aqueous phase may be a useful strategy, together with the use of a strong lipophilic emulsifier as polyglycerol polyricinoleate (PGPR). Thus, the aim of this work was to study the effect of egg white powder (EW) as gelling and stabilising agent in double emulsions. In particular, the effects of EW concentration in W1 (0, 5, 10%) as well as volume fraction of W1 (20, 30, 40%) and W1/O (40, 50, 60%) on emulsion yield, rheological behavior, and creaming stability were evaluated. PGPR was used as emulsifier, and a fixed amount of EW (5%) was added in W2. All the samples showed high yields (&gt;95%), meaning that almost all W1 remained entrapped in oil droplets. Creaming stability is of paramount importance for double emulsions intended as alternative fats in food formulation, since they have to be prepared beforehand and stored until use. The presence of EW in W1 significantly (p&lt;0.001) increased double emulsion stability after 24 h at 4\ub0C, while the samples with the lowest W1/O fraction (40%) resulted in the lowest stability (68%). Apparent viscosity and pseudoplastic behavior of double emulsions were significantly affected (p&lt;0.001) by the amount of EW in W1. Increasing EW concentration, more viscous emulsions were obtained, with lower flow index (n) values and higher consistency coefficients (K). In conclusion, the work allowed to improve the knowledge about the effects of inner water phase gelling on double emulsions characteristics, demonstrating that EW can be considered a good stabilizing agent that also improved rheological behavior of these systems

Reduced-fat soft-dough biscuits : multivariate effects of polydextrose and resistant starch on dough rheology and biscuit quality

The aim of this work was a multivariate study of polydextrose and resistant starch (high amylose maize starch; Hi-Maize\u2122 260) effects on reduced-fat soft-dough biscuits. Design of Experiments and Response Surface Methodologies were applied to model the effects on dough rheology and biscuit quality of a partial substitution of fat with polydextrose (0e50%) and of flour with resistant starch (0e80%). The calculated models evidenced highly significant effects (p < 0.001) of the experimental factors on dough density and rheological behaviour and on most biscuit characteristics (colour, milk absorption, and fracture strength). With the increase of shortening reduction, higher density and lower complex modulus of dough were observed. The biscuit quality characteristics most influenced by shortening and flour substitution were fracture strength and strain, redness (a*), heterogeneity, and milk absorption. The obtained models were used in a desirability function for the optimization of the reduced-fat formulation based on the following constraints: 25e50% shortening reduction; 41e44 g/100 g milk absorption; 100 e160 kPa fracture strength. The optimized product (17.54 \ub1 0.05 g/100 g fat), obtained with 46.3% shortening reduction and 12.5% flour replacement, had quality characteristics similar to those of full-fat biscuits (31.1 \ub1 0.4 g/100 g fat)

Effect of physicochemical and empirical rheological wheat flour properties on quality parameters of bread made from pre-fermented frozen dough

The objective of this study was to examine the influence of flour quality on the properties of bread made from pre-fermented frozen dough. The physicochemical parameters of 8 different wheat flours were determined, especially the protein quality was analysed in detail by a RP-HPLC procedure. A standardized baking experiment was performed with frozen storage periods from 1 to 168 days. Baked bread was characterised for specific loaf volume, crumb firmness and crumb elasticity. The results were compared to none frozen control breads. Duration of frozen storage significantly affected specific loaf volume and crumb firmness. The reduction of specific loaf volume was different among the used flours and its behaviour and intensity was highly influenced by flour properties. For control breads wet gluten, flourgraph E7 maximum resistance and RVA peak viscosity were positively correlated with specific loaf volume. However, after 1\u201328 days of frozen storage, wet gluten content was not significantly influencing specific loaf volume, while other parameters were still significantly correlated with the final bread properties. After 168 days of frozen storage all breads showed low volume and high crumb firmness, thus no significant correlations between flour properties and bread quality were found. Findings suggest that flours with strong gluten networks, which show high resistance to extension, are most suitable for frozen dough production. Furthermore, starch pasting characteristics were also affecting bread quality in pre-fermented frozen dough