Philippine Rices as Substrates in the Production and Utilization of Biopigments from Monascus Purpureus Went

Deficiency

XVII. Philippine Rices as Substrates in the Production and Utilization of Biopigments from Monascus Purpureus Went

HF Mamucod, MV Romero, and EI Dizon

The fungus Monascus purpureus has been the subject of extensive research because of its potential as natural colorant and dietary supplement.

The fungus is traditionally cultivated on starch-containing substrate such as rice, resulting in a fermented product known as red mold rice (RMR) or angkak. This product is used commonly in Asia as a natural food colorant in fish, soy cheese, red wine, rice koji, meat, and meat products such as sausages. Mevinolin or monacolin K, the active component of RMR, is considered a cardiovascular agent capable of reducing total cholesterol, low- density lipoprotein, and triglyceride levels. In the Philippines, RMR is used for coloring burong isda (fermented fish and rice) and bagoong (fermented fish paste). Imported either from Taiwan or China, the availability of RMR is seasonal and very limited. It is found only in few areas, particularly in Central Luzon, where fermented fish products are processed. Because of its enormous economic and health potential, production of RMR locally would be a lucrative venture. Thus, this research aimed to generate vital information that can propel the possible production of RMR in the country and to maximize its utilization. Specifically, it sought to identify mold isolate and suitable Philippine rice variety for maximum pigment production, to develop efficient processing technologies for RMR production and pigment extraction, to generate data on the antioxidant activity, total phenolic content, antimicrobial properties, and mevinolin content of Monascus pigments, to evaluate shelf-life and identify suitable packaging for RMR or Monascus pigments, and to enhance the utilization of Monascus pigments through development of value-added products.

A B C

Highlights:

• Ten Monascus isolates were screened for pigment production.

Among the isolates, B2 produced the pigments with highest optical density (2701.42 AU/g dry wt.) using potato dextrose (PD) broth during submerged culture fermentation. This was followed by B1 (818.25 AU/g dry wt.). The optical densities of the pigments produced by the other isolates ranged from 46.52 to 343.55 AU/g dry wt (Figure 35). No significant differences were observed among the biomass of the isolates.

In solid-state fermentation, B2 also gave the pigment with the highest optical density (729.18 AU/g dry wt.), followed by B1 (556.72 AU/d dry wt.) (Figure 36).

• On the optimization of process parameter, pigment production was highly affected by the substrate’s pH. On PD broth, B2 produced the pigments with highest optical density at pH 6.5 (2646.47 AU/g dry wt.) (Figure 37). The same trend was observed in solid-state fermentation (Figure 38). Rice at pH 6.5 provided the optimum condition for pigment production of B2 isolate (755.69 AU/g dry wt.). However, comparable results were also obtained at pH 5.5 (653.39 AU/g dry wt.) and 7.5 (497.9 AU/g dry wt.). For moisture content optimization, significantly higher amount of pigments were produced in rice with 30 to 40% moisture (538.61 to 705.43 AU/g dry wt.) (Figure 39). Higher moisture content resulted in reduced production of pigments and agglomeration of grains. In terms of temperature requirement, B2 produced the pigment with the highest optical density at 30 (574.98 AU/g dry wt.) to 37°C (593.57 AU/g dry wt.) (Figure 40). The isolate barely survived at 16 and 50°C.

• To identify the suitable rice variety for RMR production, four common rice samples with varying amylose content and sizes were screened. Result showed that higher amount of pigments was obtained from long-grain and non-glutinous rice varieties NSIC Rc160, NSIC Rc222, and NSIC Rc282 with optical densities of 702.62, 539.10, and 445.81 Au/g dry wt., respectively. Monascus purpureus, cultivated on glutinous rice, NSIC Rc13, produced sticky and clumped RMR (Figure 41).

• The effect of RMR supplementation on the quality of cookies (Figure 42) was evaluated. Result of the laboratory sensory analysis showed that color of the samples was highly distinguished by the panelists. Among the samples, cookie supplemented with 3% RMR was rated as darkest or reddest.

RMR supplementation had no significant effect on the aroma,

taste, mouthfeel, and tenderness of the cookies. RMR did not impart any significant off-odor to the cookies. Unfortunately, cookie treated with 3% RMR had pronounced off-flavor mainly attributed to bitterness of the sample. This perception resulted in its significantly lower over-all acceptability rating.

At 0.5 to 2.0% RMR supplementation, bitterness was no longer perceived. Cookies with 0.5 up to 1.0% RMR had over-all acceptability scores comparable with the control sample (Table 40).

Figure 35. Optical density (AU/g dry wt.) of pigments produced by the 10 Monascus isolates cultivated on PD broth.

Figure 36. Optical density (AU/g dry wt.) of pigments produced by the 10 Monascus isolates cultivated on NSIC Rc160 rice.

Figure 37. Optical density (AU/g dry wt) of pigments produced by B2 isolate cultivated on PD broth with different pH levels.

Figure 38. Optical density (AU/g dry wt) of pigments produced by B2 isolate cultivated on rice with different pH levels.

Figure 39. Optical density (AU/g dry wt.) of pigments produced by B2 isolate cultivated on rice with different moisture content.

Figure 40. Optical density (AU/g dry wt.) of pigments produced by B2 isolate cultivated on rice and incubated at different temperatures.

Figure 41. RMR produced from four common rice varieties.

Figure 42. Cookies supplemented with RMR

Table 40. Laboratory sensory scores of cookies supplemented with RMR (n=11).

Sensory attributes

Percent (%) RMR powder

0 0.5 1 2 3

Appearance

Color¹ 0.00^e 5.17^d 7.83^c 11.96^b 15.00^a

Surface

texture² 2.51^b 3.27^ab 3.75^ab 3.95^ab 4.78^a

Aroma

(plesant)³ 8.53^a 7.47^a 7.66^a 7.70^a 6.58^a

Off-odor

(moldy)³ 0.00 0.00 0.00 0.00 0.00

Taste

(pleasant)³ 8.07^a 7.75^a 7.11^a 6.53^a 5.12^a

Aftertaste⁴ 0.00^b 0.00^b 0.91^b 2.59^b 6.60^a

Mouthfeel⁵ 5.05^a 6.16^a 6.10^a 6.28^a 6.50^a

Moistness⁶ 2.90^a 1.75^ab 1.36^b 1.40^b 1.47^b

Tenderness⁷ 4.31^a 3.83^a 4.56^a 3.22^a 3.67^a

Overall

acceptabilty⁸ 10.88^a 10.55^a 9.75^a 6.77^b 5.49^b Rank score⁹ 1.64^d 2.09^cd 3.09^bc 3.91^ab 4.27^a

10=old yellow; 15= dark/reddish brown ⁶0=dry; 15=very moist

20=smooth; 15=very rough ⁷0=hard; 15=very tender

30=none; 15= very intense ⁸0=dislike; 15=like very much

40=none; 15=very perceptible ⁹1=highest; 5=lowest

50=smooth; 15=very grainy

XVIII. Elucidation of Growth Promotion Mechanisms of