346 G. McCOLLUM AND E. BALDWIN
- Impact of HLB on Orange Fruit/Juice Flavor. The impact of HLB dis-
ease (CLas infection) on fruit flavor was first reported as diseased fruit
having a bitter or salty taste, especially early in the season (McClean
and Schwarz 1970) and the flavor effects were reportedly due to higher
acidity and lower sugars (da Grac ̧a 1991). A Brazilian study (Bassanezi
et al. 2009) found HLB-affected “Valencia,” “Hamlin,” “Westin,” and
“Pera” fruit were smaller, more acidic, while percent juice, Brix, totalˆ
soluble solids, and Brix/acid ratio were all lower.
Four to 5 years after HLB disease was discovered in Florida, sev-
eral studies were conducted on flavor effects for hand juiced or simu-
lated commercially processed Florida orange juice made from healthy,
asymptomatic and HLB-symptomatic fruit. Although most of the fla-
vor studies were done on fresh or processed orange juice, since the fla-
vor of citrus fruit is predominantly from the juice in the juice sacs,
the studies on orange juice can be more or less extrapolated to the
fresh fruit. Results showed that oranges from HLB-affected trees (deter-
mined by visual symptoms and/or by qPCR for CLas (16S rDNA) had
off-flavor in that they were generally more sour and bitter than juice
made with oranges from healthy trees as determined by sensory pan-
els including triangle tests (ASTM 2003), difference from control tests
(DFC) (Meilgaard et al. 1999) and trained descriptive panels (Plotto et al.
2010). HLB-affected fruit received descriptors like “bitter,” “sour,” and
“grapefruit-like” for DFC tests, and “sour-fermented,” “salty-umami,”
“pungent,” “sour,” “peppery,” “metallic,” “bitter,” “earthy/musty,”
“astringent,” and with a “tingling” effect on the tongue for trained
descriptive panels. The HLB-affected fruit were found to be smaller
and greener in general (Baldwin et al. 2010; Massenti et al. 2015) and
analyses showed that these juices were lower in total soluble solids
and solids/acid ratio, sometimes higher in acids and higher in bitter
limonoids (Table 7.2), especially juice from HLB-symptomatic fruit. The
effects were more pronounced in “Hamlin” compared to “Valencia,”
Table 7.2. Healthy and HLB symptomatic (HLBs) orange juice soluble solids (SSC),
titratable acidity (TA), SSC/TA ratio, and bitter limonoids (limonin and nomilin) of
“Hamlin’ and “Valencia’ orange juice.
Cultivar
Disease
stateg/100 mL
SCCg/100 mL
TA SCC/TAμgg−^1
limoninμgL−^1
nomilinHamlin Healthy 11.4+0.6 0.52+0.0 21.8+1.1 0.64+0.02 0.06+0.00
HLBs 11.8+0.3 0.52+0.0 21.6+1.6 2.44+0.12 0.25+0.01
Valencia Healthy 12.2+0.2 0.62+0.2 17.9+0.1 0.85+0.01 0.22+0.02
HLBs 11.8+0.3 1.10+0.1 10.2+0.1 0.24+0.09 0.69+0.09
Source: Raithore et al. 2015.