Sensory profile and consumer acceptance of flavored soy milk beverage

Introduction

Consider a protein source that costs less than dairy, requires no refrigerated supply chain, and delivers complete amino acids along with isoflavones linked to cardiovascular and bone health-yet struggles to find buyers [1] . That is the paradox of soy milk in Indonesia. Despite the country being a significant soybean producer in Southeast Asia, soy milk is widely consumed yet flavoured variants remain under-explored because the characteristic beany offflavour, caused by lipoxygenase-catalysed oxidation of polyunsaturated fatty acids, puts off first-time consumers [2] . Flavouring-adding sweetened chocolate, fruit, or spice flavour systems-is the most straightforward approach to masking beany notes without altering the nutritional profile [3] . But flavouring success depends on the specific base's composition and the target consumer's palate. Indonesian consumers, accustomed to spiced dairy beverages (lassi, chaas, flavoured milk), may respond differently to the same flavour set that works in East Asian or Western markets [4] . This research therefore prepared soy milk from a widely cultivated Indonesian soybean variety and tested four flavour systems-vanilla, chocolate, strawberry, and cardamomusing both trained-panel descriptive analysis and untrained-consumer hedonic evaluation.

Material and Methods

Material

Soybean seeds (Anjasmoro) were procured from the seed store of the Bogor Agricultural University, Bogor, West Java. Sugar, cocoa powder, vanilla extract, strawberry flavour essence, and cardamom powder were food-grade. Work was conducted during July-October 2023 [5] .

Methods

Soy milk was prepared by the Illinois method: soybeans were soaked (1:3 w/v, 8 h), blanched (100 °C, 10 min to inactivate lipoxygenase), ground with hot water (1:6 w/v), and filtered. The filtrate was heated to 90 °C for 15 min, cooled, and divided into batches. Flavouring agents were added at standardised rates: vanilla extract 0.5%, cocoa powder 3%, strawberry essence 0.3%, and cardamom powder 0.2%, each with 6% sugar. Beverages were homogenised, pasteurised (72 °C, 15 s), packed in sterilised glass bottles, and stored at 4±1 °C. Proximate composition (protein by Kjeldahl, fat, TSS), pH, viscosity, and colour were measured at day 0. Sensory evaluation involved two panels: (a) a 10-member trained panel using quantitative descriptive analysis (QDA) for six attributes on a 10-cm unstructured line scale; (b) a 50-member untrained consumer panel using a 9-point hedonic scale [6] . Shelf-stability (pH, microbial count) was tracked at 0, 3, 6, 9, 12, and 15 days. Data were analysed by ANOVA and Duncan's test (p<0.05) in SPSS v. 26.

Results

All flavoured variants had higher TSS than plain soy milk (8.2 °Brix) because of added sugar and flavour solids.

Chocolate showed the highest viscosity (186 cP), followed by strawberry (152 cP) and vanilla (124 cP), against 98 cP for plain.

Comprehensive Interpretation

Chocolate-flavoured soy milk scored highest in both trained-panel flavour intensity and consumer overall acceptance (7.9/9), with strawberry close behind (7.7). The cocoa solids effectively masked the beany note while adding appealing bitterness and colour. Plain soy milk's low acceptance (5.8) confirmed that flavouring is a practical necessity for the Indonesian palate.

Discussion

The present findings can be summarised in three points: chocolate and strawberry were the most accepted flavours; flavouring did not compromise protein content; and pH remained stable during 15-day cold storage. The literature agrees on the masking effectiveness of chocolate: Potter et al. [3] showed that cocoa volatiles suppress perception of hexanal, the primary beany compound, by competing for olfactory receptors. Strawberry's success may owe as much to its bright colour as to its flavour, since visual cues strongly influence hedonic response to beverages [7] . Cardamom, despite being a familiar spice in Indonesian dairy beverages, scored lower than expected (7.2). This may be because cardamom's eucalyptol note clashes with the underlying soy base rather than complementing it, unlike its harmonious pairing with dairy lactose [8] . The finding aligns with Giri and Mangaraj [4] , who reported that traditional Indian spices work less well in soy than in dairy matrices.

Conclusion

This research set out to identify flavour systems that can improve the consumer appeal of soy milk in an Indonesian context. Chocolate (7.9/9) and strawberry (7.

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