Elsevier

Food Chemistry

Volume 205, 15 August 2016, Pages 187-195
Food Chemistry

Use of purple durum wheat to produce naturally functional fresh and dry pasta

https://doi.org/10.1016/j.foodchem.2016.03.014Get rights and content

Highlights

  • Antioxidants in flours and pasta of purple and yellow durum wheat were evaluated.

  • Stone milling preserves higher anthocyanin and carotenoid contents in the pasta.

  • Fresh pasta retains the major pigments compared to dried pasta.

  • The purple durum wheat pasta shows reduced in vitro glycaemic index.

  • This is the first report on processing of a purple-pigmented durum wheat genotype.

Abstract

In this study, the effects of different milling procedures (roller-milling vs. stone-milling) and pasta processing (fresh vs. dried spaghetti), and cooking on the antioxidant components and sensory properties of purple durum wheat were investigated. Milling and pasta processing were performed using one purple and one conventional non-pigmented durum wheat genotypes, and the end-products were compared with commercial pasta. The results show that the stone milling process preserved more compounds with high health value (total fibre and carotenoids, and in the purple genotype, also anthocyanins) compared to roller-milling. The drying process significantly (p < 0.05) reduced the content of anthocyanins (21.42 μg/g vs. 46.32 μg/g) and carotenoids (3.77 μg/g vs. 4.04 μg/g) with respect to the pasteurisation process involved in fresh pasta production. The sensory properties of pasta from the purple genotype did not significantly differ from commercial wholemeal pasta, and its in vitro glycemic index was even lower. Thus, it is possible to consider this genetic material as a good ingredient for the production of functional foods from cereals naturally rich in bioactive compounds.

Introduction

Pasta is often consumed daily in the diet, particularly in Mediterranean areas, and it is appreciated for its textural attributes. Conventional pasta is made using the primary ingredient of durum wheat semolina, the yellow colour of which is due to carotenoid pigments (Ficco et al., 2014a). Compared to other starch-based foods, such as bread, pasta has beneficial physiological effects, as seen by low postprandial glycemic and insulinemic responses (Aston, Gambell, Lee, Bryant, & Jebb, 2008).

Over the last few decades, the increased demand for pasta fortified with bioactive compounds has led to the addition of non-durum wheat ingredients to the semolina. This has included legume flours (Fares & Menga, 2012), oregano and carrot leaf (Boroski et al., 2011) and barley flour (Verardo, Gomez-Caravaca, Messia, Marconi, & Caboni, 2011). Also, functional foods made from pigmented cereals (e.g., maize, rice, wheat) that are rich in antioxidant compounds are currently attracting wide interest (Abdel-Aal, Young, & Rabalski, 2006).

Several recent studies have focussed on the role of whole-grain diets in preventing degenerative diseases (Abdel-Aal & Rabalski, 2008, and Refs. therein). These beneficial health properties of whole-grain products have been associated with the presence of variable amounts of antioxidants, as compared to their corresponding refined flours. Many of these are scavengers of free radicals, including carotenoids (De Simone et al., 2010, Ficco et al., 2014a) and anthocyanins (Abdel-Aal et al., 2006, Ficco et al., 2014b). The anthocyanins are predominant in pigmented grain and are mainly localised to the pericarp (i.e., the outer layers of the grain) (Abdel-Aal et al., 2006, Zeven, 1991). In contrast, the carotenoids are distributed along the grain and within the endosperm (i.e., the inner part of the grain) (Borrelli et al., 2008, Hentschel et al., 2002).

Borrelli et al. (2008) studied the distribution of the yellow colour components in durum wheat whole-grain and reported that during grain milling, a lower rate of pigment reduction was observed. This arises due to their more favourable distribution along the grain, while the pasta processing affected the residual content, and thus the final colour, to a greater extent (Borrelli et al., 2003, De Simone et al., 2010). Siebenhandl et al. (2007) analysed the phytochemical profile of pigmented cereals (i.e., purple and blue wheats, black barley) using a sieving machine. They observed similar levels of carotenoids in all of the fractions of the purple wheat genotype, with more anthocyanins in the external layers, due to the location of this pigment. In addition they noted 3-fold to 5-fold higher antioxidant activities in the external layers than in the corresponding flours, which decreased further with decreasing particle size from the millstreams.

Conversely, little is known about the loss of anthocyanins and carotenoids during the processing and after the cooking of pigmented wheat products (Li et al., 2007, Pasqualone et al., 2015). Li et al. (2007) reported a total loss of anthocyanins in purple wheat-bran muffins blended with other ingredients after heat processing (at 177 °C, for 7–12 min), although other factors might be involved in anthocyanin degradation, such as light and storage conditions (Nayak, Liu, & Tang, 2015).

During processing, as well as pigment losses, many other changes can occur in terms of the appearance, colour, texture, and sensory properties (Padalino, Mastromatteo, Lecce, Cozzolino, & Del Nobile, 2013). We thus studied a purple durum wheat (PDW) genotype during milling and processing, as semi-wholemeal vs. semolina, and as fresh pasta vs. dried pasta. The aim was to investigate: (1) the effects of two milling systems on the anthocyanin and carotenoid levels and the antioxidant capacity of PDW, as compared to a yellow durum wheat (YDW) variety; (2) the effects of the pasta-making and cooking on the antioxidant components; (3) the in vitro estimated glycemic impact; and (4) the sensorial and textural properties of the different PDW pasta, as compared to YDW and commercial durum wheat pasta.

Section snippets

Raw materials and milling

Two durum wheat genotypes (Triticum turgidum subsp. durum) were used in the present study: a pigmented durum wheat genotype (accession number CItr14754), with purple grain pericarp (PDW), and the semi-dwarf durum wheat variety PR22D89, released in Italy in 2005, with yellow grain (YDW), and high agronomic and qualitative performance. The raw material used for the processing tests (i.e., the grain) came from a field trial carried out during the growing season 2013–2014 at CREA-CER in Foggia,

Distribution of qualitative components from different wheat flours

The basic qualitative parameters of the different milling products are reported in Table 1. In the purple and conventional genotypes, the total dietary fibre showed a decreasing trend from wholemeal to semolina, according to Laddomada, Caretto, and Mita (2015), with higher values in each milling product of PDW. PDW showed significantly lower PC than YDW, although they both showed similar losses in the semolina with respect to the wholemeal (7.0%, on average). The PC of the commercial durum

Conclusions

This study has shown that the choice of a suitable milling process is necessary to preserve high antioxidant components, such as TAC, YP and TEAC, to provide good raw materials for pasta processing. In addition, a study aimed to optimise the conditions for pasta processing to consistently reduce the loss of these antioxidant components is necessary.

Moreover, although the sensorial and cooking quality characteristics of these PDW and YDW semi-wholemeal pasta did not reach the quality of the

Conflicts of interest

The authors declare that they have no conflicts of interest.

Acknowledgements

This study was supported by the Italian Ministry of Economic Development, with the special Grant PAQ (Pasta e Nuovi Prodotti Alimentari ad Alta Qualità da Cereali Italiani). The original seeds of the pigmented wheats were kindly provided by Dr. Harold Bockelaman, (USDA-ARS, National Small Grain Collection, Aberdeen, USA). The authors wish to thank Christopher Berrie for scientific English language editorial assistance.

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