Formulating fruit fillings. Freezing and baking stability of a tapioca starch–pectin mixture model

Sour Cherry Pomace Valorization as a Bakery Fruit Filling: Chemical Composition, Bioactivity, Quality and Sensory Properties

Sour cherry pomace filling (SCPF) and commercial sour cherry filling (CSCF) produced on a semi-industrial scale were tested and compared in terms of food safety, chemical composition, bioactivity, quality, sensory properties and thermal stability. Both samples were safe for human consumption, thermally stable and there was a lack of syneresis. SCPF had a significantly higher fiber concentration (3.79 g/100 g) due to higher skin fraction and is considered a "source of fibers". The higher skin fraction in SCPF also resulted in a higher mineral quantity (Fe-3.83 mg/kg fw) in comparison to CSCF (Fe-2.87 mg/kg fw). Anthocyanins concentration was lower in SCPF (7.58 mg CGE/100 g fw), suggesting that a significant amount of anthocyanins was removed from SC skin during juice extraction. However, there was a lack of statistical differences in antioxidant activity between the two fillings. CSCF was more spreadable, not as firm and less sticky, with lower storage and loss modulus values than SCPF. However, both fillings exhibited acceptable rheological and textural behaviour for fruit fillings. According to the consumer pastry test, 28 participants preferred each pastry; thus, there was a lack of preference toward any of the tested samples. SCP could be used as a raw material for the bakery fruit fillings industry, which leads to the valorization of food industry by-products.

Incorporation of polyphenols in baked products

Bakery foods, including breads, cakes, cookies, muffins, rolls, buns, crumpets, pancakes, doughnuts, waffles, and bagels, etc., have been an important diet of humans for thousands of years. As the nutraceuticals with various biological activities, polyphenols, especially polyphenol-enriched products are widely used in bakery foods. The polyphenol-enriched products are mainly from fruits and vegetables, including fruits in whole, juice, puree, jam, and the powder of dried fruits, pomace, and peels. Incorporation of these products not only provide polyphenols, but also supply other nutrients, especially dietary fibers for bakery products. This chapter discussed the thermal stability of different types of polyphenols during baking, and the effect of polyphenols on the sensory attributes of baked foods. Moreover, their role in mitigation of reactive carbonyl species and the subsequent formation of advanced glycation end products, antioxidant and antimicrobial activities have been also discussed. Since polyphenols are subjected to high temperature for dozens of minutes during baking, future works need to focus on the chemical interactions of polyphenols and their oxidized products (quinones) with other food components, and the safety consequence of these interactions.

Antioxidant Activity in Frozen Plant Foods: Effect of Cryoprotectants, Freezing Process and Frozen Storage

The antioxidant activity (AOA) of plant foods is recognized as an index of the potential health benefits resulting from their consumption. Due to their high perishability and seasonality, plant foods are largely consumed or used as processed products and freezing is one of the technologies used for the production of high-quality foods. However, cell breakages occurring during freezing and frozen storage can lead to the release of antioxidant compounds and their degradation due to chemical and enzymatic oxidation reactions, and thus, they could present a lower antioxidant activity compared to the corresponding fresh product. In this context, process conditions, freezing pre-treatments and the use of cryoprotectants can limit the extent of freeze-induced damages and preserve the antioxidant activity of plant foods. This review collects and discusses the state-of-the-art knowledge on the single and combined effect of freezing and frozen storage conditions on the antioxidant activity of fruits and vegetables as well as the role of cryoprotectants. Classes of compounds responsible for the antioxidant activity of plant foods and the most common methods used for the evaluation of the antioxidant activity in vitro are also presented. The freezing principles and the effects of ice nucleation and crystallization on fruits, vegetables and their main derivatives (juices, pulps) have been addressed to highlight their impact on the AOA of plant foods. The effect of freezing and frozen storage on the AOA of plant foods resulted dependant on a series of intrinsic factors (e.g., composition and structure), while the role of extrinsic processing-related factors, such as freezing and storage temperatures, is ambiguous. In particular, many conflicting results are reported in the literature with a high variability depending on the method of analysis used for the AOA evaluation and data expression (fresh or dry weight). Other intrinsic raw material properties (e.g., cultivar, ripening degree), post-harvest conditions, as well as defrosting methods that in the majority of the studies are scarcely reported, contribute to the aforementioned discrepancies. Finally, due to the limited number of studies reported in the literature and the high variability in product processing, the effect of cryoprotectants on the AOA of plant foods remains unclear.

Influences of stir-frying and baking on flavonoid profile, antioxidant property, and hydroxymethylfurfural formation during preparation of blueberry-filled pastries

Bakery products with fruit fillings are growing fast. Blueberry-filled pastries are widely consumed in China. This study aimed to investigate the effects of two thermal processing procedures (stir-frying and baking) on flavonoid profile, antioxidant property, and hydroxymethylfurfural (HMF) formation during preparation of blueberry-filled pastries. Stir-frying contributed the most to the variations in these values in blueberry filling. Anthocyanins (48%-53% reduction in total) were more susceptible to thermal processing than flavonols (11%-16%). Among anthocyanins, delphinidin glycosides (61%-67% reduction) were the most unstable, followed by malvidin (52%-58%), petunidin (40%-45%), and cyanidin (38%-41%). A high level of HMF (300 mg/kg) was formed during stir-frying. Except for anthocyanins, baking did not significantly influence HMF formation, flavonol degradation, and antioxidant property in the fillings. Stir-frying processing conditions rather than baking must be further investigated for nutrient retention and HMF inhibition.

Hydrocolloid effect on the stabilization of vegetable purees in the process of freezing, refrigerating and defrosting

The analysis of modern concepts of the use of hydrocolloids for the stabilization of mashed products of plant origin in the freezing – storage – defrosting circle is given. The effect of hydrocolloids on the structure of vegetable purees using the example of xanthan gum, starch and inulin was studied. The most significant characteristics of the structure was identified and their descriptors were considered. Experimental data on the effect of hydrocolloids on the microstructure of vegetable purees was obtained. The expediency of using starch and xanthan gum in combination with inulin was shown. To create a viscous structure, modified starch with small granules that exhibit thermal stability in cold storage and further heat treatment were most suitable. Inulin was also not subject to changes during temperature treatments for the products with a pH higher than 3.5, but probably would not be widely used as a structurant for vegetable purees due to the weak expression of the structure-forming properties. The synergistic combinations of inulin and xanthan gum improved the organoleptic characteristics of the product, especially in cold storage. In addition, the ability of inulin to form a smooth structure in vegetable purée when enveloping the oral cavity was revealed, despite the fact that the initial product had a rather coarse fibrous consistency due to the plant origin of the ingredients. Thus, it is promising to use inulin in combination with thickeners to give the product prebiotic properties with the improved perception in consumers. The results of the studies confirm the possibility of storing vegetable purees at low temperatures for a long time without the deterioration of the structural and organoleptic properties resulting from the slowly occurring degradation processes of the individual components of the product at low temperatures, provided that the hydrocolloids under study are used.

Structure-Related Gelling of Pectins and Linking with Other Natural Compounds: A Review

Pectins are polysaccharides present commonly in dicotyledonous and non-grass monocotyledonous plants. Depending on the source, pectins may vary in molecular size, degrees of acetylation and methylation and contents of galacturonic acid and neutral sugar residues. Therefore, pectins demonstrate versatile gelling properties and are capable of forming complexes with other natural compounds, and as a result, they are useful for designing food products. This review focuses on the structure-related mechanisms of pectin gelling and linking with other natural compounds such as cellulose, hemicellulose, ferulic acid, proteins, starch, and chitosan. For each system, optimal conditions for obtaining useful functionality for food design are described. This review strongly recommends that pectins, as a natural biocomponent, should be the focus for both the food industry and the bioeconomy since pectins are abundant in fruits and may also be extracted from cell walls in a similar way to cellulose and hemicellulose. However, due to the complexity of the pectin family and the dynamic structural changes during plant organ development, a more intensive study of their structure-related properties is necessary. Fractioning using different solvents at well-defined development stages and an in-depth study of the molecular structure and properties within each fraction and stage, is one possible way to proceed with the investigation.

Use of hydrocolloids as cryoprotectant for frozen foods

Freezing is one of the widely used preservation methods to preserve the quality of food products but it also results in deteriorative changes in textural properties of food which in turn affects its marketability. Different foodstuffs undergo different types of changes in texture, taste and overall acceptability upon freezing and subsequent frozen storage. Freezing and thawing of pre-cut or whole fruits and vegetables causes many deleterious effects including texture and drip losses. The major problem in stability of ice-cream is re-crystallization phenomena which happens due to temperature fluctuations during storage and finally impairs the quality of ice-cream. Frozen storage for longer periods causes rubbery texture in meat and fish products. To overcome these problems, hydrocolloids which are polysaccharides of high molecular weight, are used in numerous food applications involving gelling, thickening, stabilizing, emulsifying etc. They could improve the rheological and textural characteristics of food systems by changing the viscosity. They play a major role in retaining texture of fruits and vegetables after freezing. They provide thermodynamic stability to ice cream to control the process of re-crystallization. Hydrocolloids find application in frozen surimi, minced fish, and meat products due to their water-binding ability. They are also added to frozen bakery products to improve shelf-stability by retaining sufficient moisture and retarding staling. Various hydrocolloids impart different cryoprotective effects to food products depending upon their solubility, water-holding capacity, rheological properties, and synergistic effect with other ingredients during freezing and frozen storage.

Characterization and bake stability of dry fruit fillings in dehydrated chiku (Manilkara zapota L. P. Royen) incorporated biscuits

Expanding the range of bakery products in terms of producing supplemented or dietetic products has been an increasingly important trend in contemporary baking. Value added products, especially products rich in fiber and phytochemicals are getting popular. Among the dry fruits used for filling, Figs were rich in ash and protein and Dates were rich in dietary fiber. Gallic acid was the dominant free phenolic acid in Fig whereas chlorogenic acid and procatechuic acid were dominant in Dates in the bound form. Farinograph water absorption, dough development time, maximum pressure (P), and extensibility (L) decreased on increase in the replacement of wheat flour with chiku powder from 0 to 30%. The dry fruit fillings in the pH range of 3.3-3.5 with 75-80°Bx showed better bake stability with respect to spreadability and breaking strength. Biscuits topped with higher °Bx fillings had higher breaking strength values even during storage. Among the gelling agents used, addition of sodium alginate stabilized and further improved the bake stability of the fillings. The chiku incorporated biscuits sandwiched with fruit filling were rich in dietary fiber. Also significant amounts of gallic acid and chlorogenic acid in free and bound form were present in the biscuit.

PRACTICAL APPLICATIONS

Bakery products can act as a vehicle for supplementation of vitamins, minerals, protein, dietary fiber, and so on, to prevent nutritive deficiencies. Among the bakery products, biscuits are shelf stable and have better consumer acceptability by all age groups. To incorporate fruits which are rich in many bioactive principles, and to add on to variety, fruit sandwiched biscuits with fruit powder in the casing too. Fillings mainly from dry fruits were prepared at varying degree brix and with different gelling agents. Biscuit sheets containing chiku powder in the formulation was topped with the fillings and looked for the bake stability with respect to texture and spreadability. Addition of fruit powder in the shells and fruit filling in between helped to increase the nutritional characteristics of the product.

Effect of freezing on microstructure and degree of syneresis in differently formulated fruit fillings

This study describes the syneresis and its effect on microstructure in fruit fillings within a wide range of the total soluble solids content and with or without hydrocolloids upon freezing. Linear models showed the relevance of the addition of pectin and gellan gum to fillings to prevent syneresis, increasing the water-holding capacity especially after freezing. Microstructural experiments by means of NMR spin-spin relaxometry combined with fluorescence microscopy allowed to observe that the continuous hydrocolloid gel, containing the dispersed solution of native fruit parts with the addition of inulin and sugars, changed its structure/distribution according to the amount of each ingredient and due to the freezing process. Relaxometry results confirmed that hydrocolloids strength was correlated (R(2)>0.92) with water-holding capacity, due to a relationship between the signal given by the water chemically exchanging with biopolymers, and the changes in the degree of syneresis.