pasta made from parboiled flour, alm

pasta made from parboiled flour, almost regardless of the pasta- making process. The minor but significant differences observed between P2 and P3 may be related to the different starch structure in these samples. It has been suggested that sequential starch gela- tinization/retrogradation cycles may result in protein entrapment in an organized starch structure (Cabrera-Chávez et al., 2012).
The nature of the proteins solubilized in the different media from the various pasta samples was investigated by SDS-PAGE. As shown in Figure 1S, buffer-soluble albumins (25, 18, and 16 kDa; Shih, 2004) were present in P1 but absent in P2 and P3, confirming the data in Fig. 5A. Some of the same low-molecular weight species were solubilized by urea in P2 and P3, along with another polypep- tide at 36 kDa, also present in urea extracts of P1 together with bands at high molecular weight (60 and 65 kDa). These bands were absent in urea extracts of P2 and P3, but the one at 60 kDa was present in both samples when extraction with urea was carried out in the presence of disulfide-reducing agents. These latter con- ditions also allowed solubilization of the 18 kDa species, but not of the one at 65 kDa, possibly as a consequence of easier physical entrapment of the latter and larger species into process-modified starch structures, as discussed above.
Supplementary material related to this article found, in the online version, at http://dx.doi.org/10.1016/j.carbpol.2012.11.047.
Thus, the pasta-making process results in almost all pro- teins being linked through hydrophobic interactions. A previous parboiling step on rice flour provides further stabilization of these interactions by intramolecular disulfide bonds, whose formation

seems insensitive to the conditions used for pasta making and apparently involving specific proteins in a preferential way.
Quantification of accessible SH groups, that may be carried out independently of protein solubility, has been applied to under- standing the nature and evaluating the extent of modification induced in cereal-based foods by processing (Cabrera-Chávez et al.,
2012; Elkhalifa et al., 2006; Mariotti et al., 2011). As shown in Fig. 5B, the number of accessible thiols decreased in the order P1 > P2 > P3 both in the absence and in the presence of urea, con- firming the impact of parboiling on the compactness of the protein matrix. The lower content of accessible thiols in P3 vs P2 indi- cates that the effects of extrusion-cooking on protein structure rearrangements are more dramatic than those of conventional extrusion. The relevance of hydrophobic interactions to the com- pactness of the protein matrix is made evident by the increase in accessible thiols upon addition of urea. Altogether, thiol acces- sibility data confirm the fundamental role of the pasta-making process in establishing the compactness of the protein aggregates, as pointed out by the solubility approaches described above.


3.3. Properties of cooked pasta as related to the starting material and the pasta-making process

3.3.1. Physical and chemical properties of cooked pasta
Data summarizing the cooking performance of the various sam- ples of rice pasta are presented in Table 1. Pasta P3, made by extrusion-cooking of flour from previously parboiled rice (PRF), gave the lowest cooking losses and the lowest water absorp- tion, and was by large the most resilient product. The impact

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pasta yang terbuat dari flour pratanak, hampir terlepas dari proses pembuatan pasta. Perbedaan-perbedaan kecil tapi significant yang diamati antara P2 dan P3 mungkin berhubungan dengan struktur Pati berbeda dalam sampel ini. Telah diusulkan bahwa berurutan Pati gela-tinization/retrogradation siklus dapat mengakibatkan jebakan protein dalam struktur terorganisir Pati (Cabrera-Chávez et al., 2012).
Sifat dari protein salubilized di media yang berbeda dari berbagai pasta sampel diselidiki oleh SDS-halaman. Seperti ditunjukkan pada gambar 1S, buffer-larut albumins (16, 18 dan 25 kDa; Shih, 2004) hadir di P1 tapi absen di P2 dan P3, confirming data dalam Fig. 5A. Beberapa spesies berat molekul rendah yang sama yang salubilized oleh urea di P2 dan P3, bersama dengan lain polypep-pasang di 36 kDa, juga hadir di ekstrak urea P1 bersama band-band di berat molekul tinggi (60 dan 65 kDa). Band ini tidak hadir pada urea ekstrak P2 dan P3, tapi satu di 60 kDa itu hadir di kedua sampel ketika ekstraksi dengan urea dilaksanakan di hadapan disulfide-mengurangi agen. Ini terakhir con-dibebaskan atas syarat juga diperbolehkan solubilization spesies kDa 18, namun tidak satu di kDa 65, mungkin akibat mudah fisik jebakan kedua dan lebih besar spesies ke dalam proses-modified Pati struktur, seperti yang dibahas diatas.
bahan tambahan yang berkaitan dengan artikel ini ditemukan, dalam versi online, di http://dx.doi.org/10.1016/j.carbpol.2012.11.047.
dengan demikian, proses pembuatan pasta mengakibatkan hampir semua pro-teins sedang dihubungkan melalui interaksi hidrofobik. Langkah parboiling sebelumnya pada beras flour menyediakan lebih lanjut stabilisasi interaksi dengan Obligasi intramolecular disulfide, pembentukan yang

tampaknya tidak sensitif terhadap kondisi digunakan untuk pasta membuat dan rupanya melibatkan specific protein dengan cara preferensial.
Quantification diakses SH kelompok, yang dapat dilakukan secara independen dari protein kelarutan, telah diterapkan di bawah-berdiri sifat dan mengevaluasi sejauh mana modification diinduksi dalam makanan berbasis sereal pengolahan (Cabrera-Chávez et al.,
2012; Elkhalifa et al., 2006; Mariotti et al., 2011). Seperti ditunjukkan pada gambar 5B, jumlah thiols diakses menurun dalam urutan P1 mengatakan P2 mengatakan P3 di dalam ketiadaan maupun di hadapan urea, con-firming dampak pratanak pada kekompakan matriks protein. Lebih rendah kandungan thiols yang dapat diakses di P3 vs P2 indi-cates efek ekstrusi-memasak pada penyusunan ulang struktur protein lebih dramatis daripada konvensional ekstrusi. Relevansi hidrofobik interaksi untuk com-pactness matriks protein dibuat jelas oleh peningkatan diakses thiols atas penambahan urea. Secara keseluruhan, thiol acces-sibility data confirm peran fundamental proses pembuatan pasta dalam membangun kekompakan agregat protein, seperti yang ditunjukkan oleh kelarutan pendekatan dijelaskan diatas.


3.3. Sifat dari pasta yang dimasak yang terkait dengan bahan awal dan proses pembuatan pasta

3.3.1. Sifat fisik dan kimia pasta dimasak
Data meringkas kinerja memasak berbagai sam-ples pasta nasi yang disajikan dalam tabel 1. Pasta P3, dibuat oleh ekstrusi-memasak flour dari beras pratanak sebelumnya (PRF), memberi kerugian terendah memasak dan terendah air menyerap-tion, dan adalah oleh besar produk paling tangguh. Dampak

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