Production of low-fat yogurt with quince (Cydonia oblonga Mill.) scalding water
Introduction
Waste water could result from several steps in the food industry like the cleaning process, the step of blanching fruits or vegetables, or as secondary by-product such as washing water during the extraction of dietary fiber. The possibility of successfully including these waste water by-products in the human food industry would help in enhancing the economic development quince producers and processors.
Quince fruit (Cydonia oblonga Miller) is not appreciated fresh because of pulp hardness, bitterness and astringency. But when ripe it is highly demanded for processing ‘marmalade’, jams, jelly and cakes (Silva et al., 2002, Silva et al., 2005). Rodríguez-Guisado et al. (2009) determined the average values for the chemical characterization of five quince fruits collected in Southeastern Spain showing high water content (76.72 g/100 g), high crude fiber content (5.33 g/100 g), and low-fat content (1.95 g/100 g). Quince (like apple and pear) is classified into the Roseaceae family and their well-established beneficial properties to human health were found mainly related to their phenolic content. Fattouch et al. (2008) reported that quince pulp extract showed a superior phenolic content (66.95 mg/100 g fresh weight) than apple pulp (27.44 mg/100 g fresh weight) and pear (24.38 mg/100 g fresh weight). So the fact that quince fruits are a source of sugars (mainly fructose, glucose, and sucrose) and phenolic compounds with antioxidant activity suggests that it is likely that a small portion of these compounds become part of the scalding water when they are processed. Quince healthy properties have been explored by several authors, a recent study has proposed the use of quince hot water, scalding water, as a functional food for its anti-allergic effects on type I allergic symptoms proved in mice and in vitro cells (Shinomiya, Hamauzu, & Kawahara, 2009). However, the reuse of water in the food industry has limits, as has been reviewed by Casani, Rouhany, and Knøchel (2005). The type of water that we are using in the present study is classified as water for direct recycling for non-food uses and cleaning (Casani et al., 2005), however, given the interesting compounds that contains and the references to its health benefits we considered to present a simple approach by directly using such water in foods.
Fermented milk products already have a positive healthy image due to the beneficial action of its viable bacteria and yogurt already have a record as being healthful (Heller, 2001). The addition of antioxidant food ingredients such as green tea and lemon, strawberry pulp and vitamin E was been also tested on dairy products (Jiménez, Murcia, Parras, & Martínez-Tomé, 2008). The purpose of incorporating ingredients known to have antioxidant activity is to increase the functionality and antioxidant activity of these foodstuffs and in this way to improve consumer’s protection against pathologies related with free radicals (Jiménez et al., 2008).
The aim of this study was to evaluate the direct use of scalding water from quince fruits scalding in a set style yogurt on yogurt quality during 28 days of refrigerated storage.
Section snippets
Materials
Quince fruits were directly collected from the quince grove of the Miguel Hernandez University (Orihuela, Alicante, Spain). Quince fruits were separately scalded at 100 °C for 3 min and immediately divided into solids (seeds, pulp, peels) and liquid. For scalding, quince:water ratio was 1:1. Seeds and peels were handy removed, the flesh part was crushed to obtain a paste. Scalding water was filtered through a cotton gauze and frozen stored until use. For best knowledge the scalding water
pH and °Brix
The average pH was 3.92 for QFP. °Brix was 11.73 in QFP. Rodríguez-Guisado et al. (2009) reported a quince fruit pH ranging from 3.60 to 3.84 and total soluble solids (as °Brix) from 11.57 to 14.70. The pH of quince scalding water was 4.83 and the °Brix 3.53.
Organic acid and sugar profile in raw materials
Table 1 shows the profile of sugars and organic acids of quince paste and scalding water and reconstituted skim milk powder.
Fructose was the predominant sugar in either QFP or QSW followed by manitol and glucose in similar amounts. Main
Conclusions
Hot water extracts from different fruits are a good source of different compounds such as polysaccharides, sucrose, minerals, phenols and flavonoids, and many of them have antioxidant activity. Quince scalding water is rich in phenolic compounds and flavonoids which provide interesting antioxidant properties, and also contain organic acids and sugars that are all extracted during scalding. The addition of quince scalding waters provides color changes and reduced the sensory scores of yogurts
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