Physicochemical, agronomical and microbiological evaluation of alternative growing media for the production of rapini (Brassica rapa L.) microgreens.
BACKGROUND
Peat-based mixes and synthetic mats are the main substrates used for microgreens production. However, both are expensive and non-renewable. Recycled fibrous materials may represent low-cost and renewable alternative substrates. Recycled textile-fiber (TF; polyester, cotton and polyurethane traces) and jute-kenaf-fiber (JKF; 85% jute, 15% kenaf-fibers) mats were characterized and compared with peat and Sure to Grow® (Sure to Grow, Beachwood, OH, USA; http://suretogrow.com) (STG; 100% polyethylene-terephthalate) for the production of rapini (Brassica rapa L.; Broccoletto group) microgreens.


RESULTS
All substrates had suitable physicochemical properties for the production of microgreens. On average, microgreens fresh yield was 1502 g m-2in peat, TF and JKF, and was 13.1% lower with STG. Peat-grown microgreen shoots had a higher concentration of K+and SO42-and a two-fold higher NO3-concentration [1959 versus 940 mg kg-1fresh weight (FW)] than those grown on STG, TF and JKF. At harvest, substrates did not influence microgreens aerobic bacterial populations (log 6.48 CFU g-1FW). Peat- and JKF-grown microgreens had higher yeast-mould counts than TF- and STG microgreens (log 2.64 versus 1.80 CFU g-1FW). Peat-grown microgreens had the highest population of Enterobacteriaceae (log 5.46 ± 0.82 CFU g-1) and Escherichia coli (log 1.46 ± 0.15 CFU g-1). Escherichia coli was not detected in microgreens grown on other media.


CONCLUSIONS
TF and JKF may be valid alternatives to peat and STG because both ensured a competitive yield, low nitrate content and a similar or higher microbiological quality. © 2016 Society of Chemical Industry.
Department of Agricultural and Environmental Science, University of Bari Aldo Moro, via Amendola 165/A, 70126 Bari, Italy.|University of Florida, Institute of Food and Agricultural Sciences, South West Florida Research and Education Center, Immokalee, FL 34142, USA.
Francesco
F
Di Gioia
Institute of Sciences of Food Production, National Research Council, via Amendola 122/O, 70126 Bari, Italy.
Palmira
P
De Bellis
Institute of Sciences of Food Production, National Research Council, via Amendola 122/O, 70126 Bari, Italy.
Carlo
C
Mininni
Department of Agricultural and Environmental Science, University of Bari Aldo Moro, via Amendola 165/A, 70126 Bari, Italy.
Pietro
P
Santamaria
Institute of Sciences of Food Production, National Research Council, via Amendola 122/O, 70126 Bari, Italy.
Francesco
F
Serio
D000383:Agriculture / Q000379:methods*; D018533:Biomass; D029741:Brassica rapa / Q000254:growth & development* / Q000378:metabolism; D015169:Colony Count, Microbial; D032381:Corchorus; D032561:Cotton Fiber; D003470:Culture Media / Q000737:chemistry*; D004755:Enterobacteriaceae / Q000254:growth & development; D004926:Escherichia coli / Q000254:growth & development; D005516:Food Microbiology; D005658:Fungi / Q000254:growth & development; D031584:Hibiscus; D006801:Humans; D009566:Nitrates / Q000032:analysis; D010795:Phthalic Acids; D011091:Polyesters; D011140:Polyurethanes; D059027:Recycling; D036226:Seedlings / Q000254:growth & development* / Q000378:metabolism; D012987:Soil; D013784:Textiles; D015003:Yeasts / Q000254:growth & development
D003470:Culture Media; D009566:Nitrates; D010795:Phthalic Acids; D011091:Polyesters; D011140:Polyurethanes; D012987:Soil; C011363:terephthalic acid
Brassica rapa L; Enterobacteriaceae; Escherichia coli; broccoli raab microgreens; peat alternative; recycled fibrous materials