Sains Malaysiana 47(11)(2018): 2685–2691

http://dx.doi.org/10.17576/jsm-2018-4711-11

 

Kajian Potensi Ekstrak Bilberi sebagai Penunjuk pH untuk Memantau Kesegaran Makanan secara Kromametri

(Potential Study of Bilberry Extract as a pH Indicator to Monitor Food Freshness by Chromametry)

 

NOOR AZIZAH AHMAD^1,2, LEE YOOK HENG^1*, FARIDAH SALAM^1,2 & SHARINA ABU HANIFAH¹

 

¹Pusat Pengajian Sains Kimia dan Teknologi Makanan, Fakulti Sains dan Teknologi, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

 

²Institut Penyelidikan dan Kemajuan Pertanian Malaysia, 43400 Serdang, Selangor Darul Ehsan, Malaysia

 

Received: 26 February 2018 /Accepted: 2 July 2018

 

ABSTRAK

Penunjuk pH sebagai suatu pendekatan untuk memantau kualiti atau kesegaran makanan semasa telah mendapat perhatian industri pembungkusan makanan. Penggunaan sumber semula jadi pigmen tumbuhan terutamanya dari buah-buahan dan sayur-sayuran menjadi pilihan para pengguna untuk menggantikan pewarna sintetik dalam memastikan keselamatan makanan yang diambil setiap hari. Dalam kajian ini, ekstrak daripada bilberi telah digunakan sebagai pewarna sensitif pH. Perubahan warna sampel dikaji secara terperinci melalui kaedah kromametri dan juga kaedah spektrofotometri ultra-lembayung nampak. Warna merah terang terhasil dalam pH berasid, merah pudar pada neutral dan magenta ke kuning dalam pH beralkali. Keputusan kajian kromametri menunjukkan bahawa ekstrak bilberi berupaya mempamerkan perubahan warna yang jelas terhadap perubahan pH, iaitu terdapat perubahan nilai warna a* yang menyumbang kepada perubahan yang bererti dalam perbezaan warna keseluruhan (ΔE*). Nilai ΔE* juga ditentukan wujud hubungan linear dan kuantitatif terhadap julat pH tertentu. Oleh yang demikian, ekstrak bilberi didapati berpotensi sebagai bahan sensor untuk pH dalam membangunkan satu sensor pH bagi memantau kesegaran makanan terutamanya hasilan laut berbungkus memandangkan tahap kerosakan produk tersebut berkait rapat dengan perubahan pH ke arah alkali.

 

Kata kunci: Antosianin; ekstrak bilberi; pH; serapan maksimum; warna

 

ABSTRACT

The use of pH indicator as an approach to monitor the quality or freshness of foods has the attention of the food packaging industry. The use of natural resources, especially plant pigments of fruits and vegetables has now become the user’s choice to replace synthetic dyes as indicators to ensure the safety of the food-consumed every day. In this study, bilberry extract was used for a pH-sensitive dye. The colour change of the sample was studied in details by chromametric and spectrophotometric methods. The bilberry extract was observed to produce bright red colour under acidic conditions, faded at neutral and changed from magenta to yellow in alkaline conditions. The results of detail chromametric studies showed that bilberry extracts were able to exhibit distinguishable colour changes at different pHs, which led to a change in a* value that eventually contributed to significant changes in the total colour difference (ΔE*). The ΔE* value also demonstrated a linear and quantitative relationships to certain pH ranges. Therefore, bilberry extract has the potential to be used as a sensor material in developing a pH sensor for the purpose of monitoring food freshness, especially packaged fishery products since deterioration level is closely related to alkaline pH changes.

 

Keywords: Anthocyanin; colour; extract; maximum absorbance; pH

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*Corresponding author; email: leeyookheng@yahoo.co.uk