Determination of free L- and D-alanine in hydrolysed protein fertilisers by capillary electrophoresis

The objective of this study was to determine the degree of racemisation of hydrolysed protein fertilisers (HPFs) using an inexpensive and easy to handle analytical method for qualitative control of the products. Using a polyacrylamide coated capillary and a run buffer containing 0.1 M Tris-borate+2.5 mM EDTA-Na2+0.1% sodium dodecylsulfate+10 mM β-cyclodextrin a quantitative separation of D- and L-alanine (Ala) was made from an not treated HPF sample derivatised with dansyl chlorine by capillary electrophoresis. The D-Ala:[D-Ala+L-Ala] ratio, called degree of racemisation (RD), was calculated. The analysis of ten commercial HPFs has shown that more than 60% of HPFs have an RD ≥40%, while only one product has shown an RD <5%. These results showed that most of the HPFs on the market are obtained with strong hydrolytic processes and high contents of D-amino acids are probably less effective as plant nutrients or even potentially dangerous to plants. © 2002 Elsevier Science B.V. All rights reserved

Determinazione della distribuzione delle masse molecolari nei fertilizzanti a base di proteine idrolizzate

I fertilizzanti a base di proteine idrolizzate (IP) sono un sistema \u201cpolidisperso\u201d caratterizzato da un ampio intervallo di masse molecolari (M). Le M di 15 campioni rappresentativi di IP sono state calcolate per HPSEC. Le medie delle M sono risultate comprese in un ampio intervallo e il grado di polidispersione \ue8 risultato compreso tra 1 e 2. I processi idrolitici utilizzati per la produzione degli IP sono risultati relativamente poco efficaci, pertanto gli IP sono caratterizzati da un ragguardevole contenuto di polipeptidi con M >10 kDa. Summary The hydrolysed protein-based fertilisers (IP) are a polydispersed and heterogeneous system characterised by a wide range of molecular weight (M). 15 commercial IP were analysed and the M was determined by HPSEC. The M of the IP resulted in a wide range and the degree of polydispersity resulted between 1 and 2. The hydrolytic processes used for IP production showed a relative low efficiency and yield IPs with a high amount of > 10 kDa polypeptides

Mineralizzazione nel suolo di farine sgrassate di semi di piante ad alto contenuto in glucosinolati: effetto sulla disponibilit\ue0 dell\u2019azoto e del fosfato

In questo lavoro sono riportati i risultati ottenuti dallo studio della mineralizzazione nel suolo di farine sgrassate ad alto contenuto in glucosinolati. La mineralizzazione apparente dell\u2019azoto e del fosfato aggiunti con le farine \ue8 stata intensa nelle prime settimane per poi stabilizzarsi dopo circa 6-8 settimane d\u2019incubazione, con valori pari a circa il 50-60% dell\u2019azoto e il 20-30 % del fosfato aggiunti. I risultati ottenuti dimostrano che questi prodotti possono essere assimilati a tutti gli effetti a concimi organici NP. Abstract In this research, we have studied the soil mineralisation of several defatted meals from glucosinolates-rich plants. The results showed that the nitrogen and phosphate apparent mineralisation was very high for the first 6-8 weeks, while in the remaining 8-10 weeks the process was negligible. The 50-60 % of added nitrogen, and 20-30 % of phosphate was apparently mineralised at the end of the incubation time. The results obtained have demonstrated that this products are potentially good organic NP fertilisers

Mineralizzazione nel suolo di farine sgrassate di semi di piante ad alto contenuto in glucosinolati: effetto sulla disponibilit\ue0 dell\u2019azoto e del fosfato.

Sommario In questo lavoro sono riportati i risultati ottenuti dallo studio della mineralizzazione nel suolo di farine sgrassate ad alto contenuto in glucosinolati. La mineralizzazione apparente dell\u2019azoto e del fosforo aggiunti con le farine \ue8 stata intensa nelle prime settimane per poi stabilizzarsi dopo circa 6-8 settimane d\u2019incubazione, con valori pari a circa il 50-60% dell\u2019azoto e il 20-30 % del fosfato aggiunti. I risultati ottenuti dimostrano che questi prodotti possono essere assimilati a tutti gli effetti a concimi organici NP. Abstract In this research, we have studied the soil mineralisation of several defatted meals from glucosinolates-rich plants. The results showed that the nitrogen and phosphate apparent mineralisation was very high for the first 6-8 weeks, while in the remaining 8-10 weeks the process was negligible. The 50-60 % of added nitrogen, and 20-30 % of phosphate was apparently mineralised at the end of the incubation time. The results obtained have demonstrated that this products are potentially good organic NP fertilisers

What we talk about when we talk about protein hydrolyzate-based biostimulants

Protein hydrolyzates (PHs) are a well-known group of plant biostimulants that are obtained by thermal, chemical, enzymatic or mixed hydrolysis from animal or plant sources. PHs are mainly applied to plants with the aim to improve their nutrition level, stimulate metabolism, and increase resistance to abiotic stress. Chemically, the PHs are a mixture of free amino acids, oligo- and polypeptides. Considering the differences in the source materials and hydrolytic processes used for their production it is not surprising that PHs are a very complex and inhomogeneous category of biostimulants. This is a critical point that should be considered by both manufacturers and potential users of such products. With the aim to identify a putative correlation among PHs physic-chemical properties, the different source materials and the hydrolytic process used for their production, 22 PHs available on the market were analyzed for: (i) total amino acids concentration, (ii) free amino acids concentration, (iii) degree of racemization, (iv) degree of hydrolysis and (v) apparent average molecular size. The obtained results confirmed the inhomogeneity PHs. However, the chosen parameters were able to provide information about the above-mentioned correlation. Total amino acids in particular were useful for the identification of the original source material. The degree of racemization was useful for the identification of the type of hydrolysis used during production (chemical or enzymatic). The degree of hydrolysis and free amino acid concentrations were useful for the identification of the intensity of the hydrolytic process. The average molecular size was useful for the identification of polydispersity of the peptide size. In conclusion, the PHs can be adequately characterized only through a multi-analytical approach