Elsevier

LWT

Volume 86, December 2017, Pages 25-30
LWT

Functional properties of fermented milk produced with plant proteins

https://doi.org/10.1016/j.lwt.2017.07.025Get rights and content

Highlights

  • Using of plant protein additives (soy, pea and rice protein and wheat gluten) in non-fat fermented milk drink formulations improved the physico-chemical and technological properties.

  • Plant protein additives increased amino acid levels and improved the nutritional value.

  • Highest essential amino acid content was found in drinks containing soy protein isolate.

  • Plant protein additives improved the sensory attributes of the milk drinks.

Abstract

In this study, storage-related changes in the physico-chemical and sensory properties of non-fat fermented milk drinks that contain soy protein isolate (SPI), pea protein isolate (PPI), wheat gluten (WG) and rice protein (RP) were investigated. The addition of plant protein additives to milk beverage affected the pH, titratable acidity %, syneresis, viscosity, dry matter, ash, color (L, b values), protein and amino acid contents (p < 0.01). During storage, the viscosity values showed an increase and protein additives increased amino acid levels in fermented milks beverage. The highest essential amino acid content was found in drinks containing SPI, with the most prevalent amino acids being lysine, leucine, isoleucine, methionine and threonine. The taste of fermented milks with PPI was preferred. In general, plant protein additives improved the sensory attributes. (p < 0.01). In conclusion, the use of plant protein additives in non-fat fermented milk drink formulations was shown to improve the physico-chemical and sensory properties and to increase the nutritional value of the formulations and therefore could be an alternative strategy for the development of new healthy dairy products.

Introduction

Recently, there has been a surge in research on the role of functional foods, nutraceuticals, and food supplements for improving human health. Functional foods are whole, fortified, enriched or enhanced foods that provide health benefits beyond essential nutrients (e.g., proteins, carbohydrates, fatty acids, vitamins and minerals) (Betoret et al., 2011, Hasler, 2002). Functional foods have also been associated with health benefits because they contain bioactive peptides, oligosaccharides, organic acids, highly absorbable calcium, conjugated linoleic acid and other biologically active components, for example, foods enriched with probiotics, prebiotics, flavonoids, carotenoids, and conjugated linoleic acid (CLA) (Cencic and Chingwaru, 2010, Roberfroid, 2000). A functional food that aids in the prevention and/or treatment of a disease(s) and/or disorder(s) other than anemia is called a nutraceuticals (Trottier, Bostrom, Lawrentschuk, & Fleshner, 2010).

Development of new dairy-derived functional food products is very challenging because of high consumer expectations for palatability and healthiness. Ingredients such as proteins, vitamins and minerals used in the fortification of functional foods exhibit potential health benefits that are widely recognized and accepted by consumers (Delikanli and Ozcan, 2014, Fogliano and Vitaglione, 2005, Shah, 2007). Dairy products can improve health or well-being, and when consumed at recommended levels, their benefits include improved immune system function, antimicrobial effects, reduced risk of cardiovascular and gastro-intestinal diseases, improved psychological functions, reduced risk of low bone mass and antioxidant properties that protect against free radical damage (Granato et al., 2010, Homayouni et al., 2012, pp. 197–212).

A fermented milk product has been defined by the International Dairy Federation as a milk product prepared from skimmed or unskimmed milk with specific cultures. Fermented dairy products have biologically active components that have long been an important part of a nutritional diet. Incorporating plant proteins into fermented milk provides a good alternative method for enriching the protein quality of dairy products (Korhonen and Ve Pihlanto, 2006, Panesar, 2011). Dairy proteins and peptides also improve the bioavailability of minerals and trace elements, such as calcium, magnesium, manganese, zinc, selenium and iron (Vegarud, Langsrud, & Svenning, 2000). Additionally, dairy products have the potential to contribute to the prevention and management of obesity (Luhovyy, Akhavan, & Anderson, 2007).

Dietary proteins are essential compounds that build and repair body tissues. Specific health conditions such as illness, physiological stress, pregnancy and breast-feeding, and infections can benefit from increased protein consumption. Malnutrition continues to be a major public health problem throughout the developing world, particularly in southern Asia and Africa. Kwashiorkor and marasmus are the two most common forms of protein-energy malnutrition (PEM). Marasmus involves inadequate intake of protein and calories, whereas a child with kwashiorkor has fair-to-normal calorie intake with inadequate protein intake (Bain et al., 2013, Müller and Krawinkel, 2005).

Legumes (the poor man's meat) and cereals offer new approaches to improve the nutritional value of foods and decrease protein malnutrition because they are relatively inexpensive and are rich sources of protein and calories and are valuable foods for both economic and cultural reasons in some countries (Angelov et al., 2006, Bain et al., 2013, Charalampopoulos et al., 2002, Zare et al., 2012).

For the past few years, protein hydrolysates from sources such as soybean, egg, whey, casein, potato, chickpea, canola, corn, wheat gluten, silky fowl, rice endosperm, and rice bran have been used to improve the nutritional values of foods and have been used to enrich the antioxidant, amino acid, peptide, and protein content of foods due to their low costs and safety (Adebiyi et al., 2008, Elias et al., 2008, Li et al., 2008, Shih and Daigle, 2000, Zhu et al., 2008).

The objective of this study was to evaluate the properties of fermented milk enriched with plant proteins and to investigate the feasibility of using different proteins derived from plants such as soy, pea, wheat, and rice.

Section snippets

Preparation of fermented milks

The fermented milks (FMs) were prepared using a lyophilized thermophilic lactic acid bacteria of YC-350 (Thermophilic Yoghurt Culture- Yo-Flex®, Chr Hansen) composed of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus. The starter culture was propagated in flasks by reconstituting to 10.70% w/v in sterile skim milk (RSM) prepared from low-heat skim milk powder (LHSMP) at 121 °C for 15 min (Ozcan, Horne, & Lucey, 2015). The culture was incubated at 42 ± 1 °C for 72 h.

Physicochemical composition

The physicochemical properties of the fermented milk samples are shown in Table 1. The pH values decreased in parallel with an increase in titration acidity values throughout the storage period, as a result of continued bacterial activity in the fermented milk beverages. The results obtained show that titrable acidity of fermented milks containing wheat gluten (WG) were significantly higher and their pH values were significantly lower than that of the other fermented milk beverages. One

Conclusion

It has been found that the plant protein additives that had different compositions and were obtained by different methods enhanced the physico-chemical and sensory characteristics of non-fat fermented milk beverages, enriched their amino acid content and can be used in developing functional milk products. The application of plant proteins with specific combinations of pro- and prebiotics in the production of fermented dairy products can improve the nutraceutical properties and nutritional value

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    This study is a part of Zeynep Akin's M.Sc. thesis submitted to the Uludag University, Institute of Natural Sciences.

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