Fresh juice from C grade longan (mg/g fresh fruit; total sugars 51.6 ± 0.5, nitrogen 0.021 ± 0.004; gallic acid 0.025 ± 0.001; ellagic acid 0.016 ± 0.001) with addition of 8.52 g ammonium sulfate/l was the optimal medium for cultivation processes of Saccharomyces cerevisiae TISTR 5606 and Candida tropicalis TISTR 5306 capable of producing ethanol and phenylacetylcarbinol (PAC) among five longan grades. S. cerevisiae TISTR 5606 produced ethanol (33.4 ± 3.2 g/L) at a significantly higher level (p ≤ 0.05) than C. tropicalis TISTR 5306 (22.3 ± 1.1 g/L) with similar ethanol yields (Yp/s) between 0.21 and 0.22 g ethanol produced/g sugars consumed. Whole cells of C. tropicalis TISTR 5306 produced a significantly higher (p ≤ 0.05) PAC level (27.2 ± 0.7 mM) than S. cerevisiae TISTR 5606 (3.59 ± 1.33 mM) after 6 hr in an equivalent volume biphasic biotransformation system. Practical applications Longan is one of the important economic fruit of Thailand with production volume in 2017 reaching one million tons. Less than 10% of these are domestically consumed while more than 90% are exported to several countries whose population frequently consume longan as a nutritious food supplement. This study can help solving overproduction problem of longan fruit by processing C grade fresh longan, which is accounted for 5% of the overall production volume, in the form of juice extract with the relatively high sugars content. Microbial fermentation of this juice and subsequent whole cells biotransformation process result in ethanol and PAC, respectively. Ethanol can be used as an alternative biofuel or important industrial solvent while PAC is a precursor for production of commercial nasal decongestant (ephedrine) or anti‐asthmatic compound (pseudoephedrine).

The abilities of isolates to survive and be active in anaerobic and aerobic conditions rendered them to be active in cattle's rumen. Their biomass could be produced in bulk and used as feed supplement for aflatoxin detoxification in dairy cattle.

The objective of this study was to determine the effect of supplementing Kluyveromyces marxianus CPY1, K. marxianus RSY5 and Pichia kudriavzevii YSY2 isolated from ruminal fluid of dairy cows on transfer of aflatoxin B1 (AFB1) from feed into aflatoxin M1 (AFM1) in milk, DMI, milk production and nutrient digestibility. Four multiparous Holsteins in mid-lactation were used in a 4 × 4 Latin square design trial consisting of 14 days in each experimental period for sample collection. Between each period, 14 clearance days prior to the next treatment were allowed to minimize carryover effects. In each treatment, subsequent supplementation of isolated yeast was compared, i.e., (1) control (without yeast supplementation), (2) K. marxianus CPY1 (K1Y), (3) K. marxianus RSY5 (K2Y) and (4) P. kudriavzevii YSY2 (PY). All diets contained 22.28 µg of AFB1/kg. Treatments were individually fed at the rate of 2 g/day (1 × 109 CFU/g) of yeast biomass or corn meal in the control group. Concentrations of AFM1 in milk was reduced with yeast and averaged 1.54, 0.36, 0.43 and 0.51 µg/L for control, K1Y, K2Y and PY, respectively (p < 0.01). The transfer of AFB1 from feed into AFM1 in milk was higher in control compared with K1Y, K2Y and PY (7.26% vs. 1.18%, 1.44% and 1.69% respectively, p < 0.01). Supplementation of yeast also improved DMI and milk compositions, but no differences were observed in nutrient digestibility or milk yield among treatments. Concentration and yield of milk protein, fat, lactose, solid-not-fat (SNF) and total solids were greater in cows fed yeast compared with the control (p < 0.01). These results indicate that K. marxianus CPY1, RSY5 and P. kudriavzevii YSY2 shows promise as a dietary supplementation to detoxify AFB1 and improve DMI and yield of milk components.

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